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antenna

antenna

antenna Sentence Examples

  • (ii) The antenna may have oscillations excited in it inductively.

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  • (ii) The antenna may have oscillations excited in it inductively.

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  • The wheel was connected to a receiving antenna and the mercury to earth or to an equivalent balancing capacity.

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  • This elevated conductor is now called the antenna, aerial wire, or air wire.

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  • a b, constantan wire; c d, thermojunction; G G, galvanometer terminals; 0 0, antenna and earth terminals.

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  • a b, constantan wire; c d, thermojunction; G G, galvanometer terminals; 0 0, antenna and earth terminals.

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  • To detect these currents some device has to be inserted in the antenna circuit or else inductively connected with it which is sensitive to high frequency currents.

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  • This condenser is charged electrically and then suddenly discharged and violent electrical oscillations are set up in it, that is to say, electricity rushes to and fro between the antenna and the earth.

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  • Instead of inserting the sensitive tube between the receiving antenna and the earth, he inserted the primary coil of a peculiar form of oscillation transformer and connected the terminals of the tube to the secondary circuit of the transformer.

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  • The antenna has at one moment a static electrical charge distributed upon it, and lines of electric force stretch from it to the surrounding earth.

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  • Hence devices for detecting the oscillations in the antenna are merely very sensitive forms of ammeter and voltmeter.

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  • In any case the antenna serves as one surface of a condenser, the other surface of which is the earth.

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  • When used as a receiver for wireless telegraphy Marconi inserted the oscillation coil of this detector in between the earth and a receiving antenna, and this produced one of the most sensitive receivers yet made for wireless telegraphy.

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  • When oscillations are excited in this last circuit they communicate them to the antenna provided this last circuit is tuned or syntonized to the closed circuit, and the radiating antenna has thus a large store of energy to draw upon and can therefore radiate prolonged trains of electric waves.

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  • It was then found that when electric waves fell on the antenna a sound was heard in the telephone as each wave train passed over it, so that if the wave trains endured for a longer or shorter time the sound in the telephone was of corresponding duration.

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  • If the direct coupling is adopted then the lower end of the antenna is connected directly to the condenser circuit.

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  • This consists of a receiving antenna similar to the sending antenna, and in any wireless telegraph station it is usual to make the one and the same antenna do duty as a receiver or sender by switching it over from one apparatus to the other.

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  • When electric waves fell on the antenna they caused the mercury-steel junction to become conductive during the time they endured, and the siphon recorder therefore to write signals consisting of short or long deflexions of its pen and therefore notches of various length on the ink line drawn on the strip of telegraphic tape.

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  • If we consider the lines of magnetic force in the neighbourhood of the receiving antenna wire we shall see that they move across it, and thus create in it an electromotive force which acts upon the coherer or other sensitive device associated with it.

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  • In the case of the plain or directly excited antenna the oscillations are highly damped, and each train probably only consists at most of half a dozen oscillations.

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  • These two circuits are syntonized so that the closed or condenser circuit and the open or antenna circuit are adjusted to have, when separate, the same natural electrical time of vibration.

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  • At a later date a syntonic system comprising, as above stated, an antenna directly coupled to a resonant closed circuit was put into operation by Lodge and Muirhead, and much the same methods have been followed in the system known as the Telefunken system employed in Germany.

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  • These static and kinetic conditions succeed each other rapidly, and the result is to detach or throw off from the antenna semi-loops of electric force, which move outwards in all directions and are accompanied by expanding circular lines of magnetic force.

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  • The above statements, though correct as far as they go, are an imperfect account of the nature of the radiation from a coupled antenna, but a mathematical treatment is required for a fuller explanation.

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  • The above statements, though correct as far as they go, are an imperfect account of the nature of the radiation from a coupled antenna, but a mathematical treatment is required for a fuller explanation.

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  • Marconi exhibited in October 1900 this apparatus in action, and showed that two or more receivers of different tunes could be connected to the same antenna and made to respond separately and simultaneously to the action of separate but tuned transmitters.

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  • D and spark gap, has the same natural time period of oscillation as the open circuit consisting of the antenna, secondary coil and adjustable inductance.

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  • In practical wireless telegraphy the antenna is generally a collection of wires in fan shape upheld from one or more masts or wooden towers.

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  • In one of these ways the oscillations can be created or stopped at pleasure in the radiating antenna, and hence groups of electric waves thrown off at will.

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  • If, however, the antenna is inductively or directly coupled to a condenser circuit of large capacity then the amount of energy which can be stored up before discharge takes place is very much greater, and hence can be drawn upon to create prolonged or slightly damped trains of waves.

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  • If, however, one electrode of this cell is connected to the earth and the other to a receiving antenna and electric waves allowed to fall on the antenna, the oscillations passing through the electrolytic cell will remove the polarization and L temporarily decrease the resistance of the cell.

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  • Such an oscillation valve was first used by Fleming as a receiver for wireless telegraph purposes in 1904 as follows: - In between the receiving antenna and the earth is placed the primary coil of an oscillation transformer; the secondary circuit of this transformer contains a galvanometer in series with it, and the two together are joined between the external negative terminal of the carbon filament of the above-described lamp and the insulated platinum plate.

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  • an antenna of suitable capacity and inductance to a nearly closed electric circuit consisting of a condenser of large capacity, a spark gap and an inductance of low resistance.

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  • Braun showed that oscillations suitable for the purposes of electric wave creation in wireless telegraphy could be set up in a circuit consisting of a Leyden jar or jars, a spark gap and an inductive circuit, and communicated to an antenna either by inductive or direct coupling (Brit.

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  • This corresponds to the electrical discharge of the antenna, and the subsequent string vibrations to the electrical vibrations.

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  • If these spark balls are set at the right distance, then when the potential difference accumulates the antenna will be charged and at some stage suddenly discharged by the discharge leaping across the spark gap. This was Marconi's original method, and the plan is still used under the name of the direct method of excitation or the plain antenna.

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  • Braun suggested in 1898 that the oscillatory discharge of a Leyden jar should be sent through the primary coil of a transformer and the secondary coil should be interposed between the antenna and an earth connexion.'

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  • The receiving arrangement consists of an antenna which is connected to earth through the primary coil of an oscillation transformer and a variable inductance.

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  • He therefore saw that it was a mistake to insert a potential-affected detector such as a coherer in between the base of the antenna and the earth because it was then subject to very small variations of potential between its ends.

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  • It was also recognized that what is required at the transmitting end is the establishment of powerful electric oscillations in the sending antenna, which create and radiate their energy in the form of electric waves having their magnetic force component parallel to the earth's surface and their electric component perpendicular to it.

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  • - A, antenna; P S, jigger or oscillation transformer; C, condenser; 0, Fleming oscillation valve; B, working battery; T, telephone; R, rheostat; E, earth-plate.

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  • He showed that in a simple Marconi antenna the variations of potential are a maximum at the insulated top and a minimum at the base, whilst the current amplitudes are a maximum at the top earthed end and zero at the top end.

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  • He overcame the difficulty by erecting a vertical earthed receiving antenna like a lightning rod and attached a lateral extension to it at a yard or two above the earthed end.

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  • The oscillations set up in the vertical antenna excited sympathetic ones in the lateral circuit provided this was of the proper length; and the coherer was acted upon by the maximum potential variations possible.

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  • The receiving arrangements comprised also an open or antenna circuit connected directly with a closed condenser-inductance circuit, but in place of the spark gap in the transmitter an electrolytic receiver was inserted, having in connexion with it as indicator a voltaic cell and telephone.

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  • 38 6), the insulated wires or plates being upheld by masts, its operation is as follows: - When the key in the primary circuit of the induction coil is pressed the transmitting antenna wire is alternately charged to a high potential and discharged with the production of high frequency oscillations in it.

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  • The antenna wire, connected to one spark ball of the induction coil, must be considered to form with the earth, connected to the other spark ball, a condenser.

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  • First as regards the transmitting part, one essential element is the antenna, aerial, or air wire, which may take a variety of forms. It may consist of a single plain or stranded copper wire upheld at the top by an insulator from a mast, chimney or building.

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  • This creates rapid variations in electric and magnetic force round the antenna and detaches energy from it in the form of an electric wave.

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  • (iii) The antenna may be direct-coupled to the closed oscillatory circuit in the manner suggested by F.

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  • The electric waves coming through space from the sending station strike against the receiving antenna and set up in it high frequency alternating electromotive forces.

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  • This periodic distribution in time and space constitutes an electric wave proceeding outwards in all directions from the sending antenna.

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  • This strain corresponds to the electrical charging of the antenna.

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  • When this is the case, if discharges are made across the spark gap oscillations are excited in the closed circuit, and these induce other syntonic oscillations in the antenna circuit.

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  • 2 The tube provided with certain screw adjustments had a single cell and a telephone placed in series with it, and one end of the tube was connected to the earth and the other end to a receiving antenna.

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  • Over this primary is wound a secondary circuit of five to ten turns which has one end connected to the earth through a variable inductance coil and the other end to an antenna.

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  • Slaby paid considerable attention to the study of the phenomena connected with the production of the oscillations in the antenna.

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  • When the methods for effecting this had been worked out practically it finally led to the inventions of Slaby, Braun and others being united into a system called the Telefunken system, which, as regards the transmitter, consisted in forming a closed oscillation circuit comprising a condenser, spark gap and inductance which at one point was attached either directly or through a condenser to the earth or to an equivalent balancing capacity, and at some other point to a suitably tuned antenna.

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  • In the same way the arrangements finally elaborated by Lodge and Muirhead consisted of a direct coupled antenna and nearly closed condenser circuit, and a similar receiving circuit containing as a detector the steel wheel revolving on oily mercury which actuated a siphon recorder writing signals on paper tape.

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  • All of them make use of Marconi's antenna in some form both at the transmitting and at the receiving end, all of them make use of an earth connexion, or its equivalent in the form of a balancing capacity or large surface having capacity with respect to the earth, which merely means that they insert a condenser of large capacity in the earth connexion.

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  • All of them couple the transmitting antenna directly or inductively to a capacity-inductive circuit serving as a storage of energy, and all of them create thereby electric waves of the same type moving over the earth's surface with the magnetic force of the wave parallel to it.

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  • The first antenna employed consisted of 50 bare copper wires 200 ft.

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  • Subsequently this antenna was enlarged, and four wooden lattice towers were built, 215 ft.

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  • At St John's in Newfoundland he erected a temporary receiving antenna consisting of a wire 400 ft.

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  • 771818) to employ a receiving antenna consisting of vertical wires held in a frame which could be swivelled round into various positions and used to locate the position of the sending station by ascertaining the position in which the frame must be placed to create in it the maximum oscillatory current.

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  • He showed that if an antenna were constructed with a short part of its length vertical and the greater part horizontal, the lower end of the vertical part being earthed, and if oscillations were created in it, electric waves were sent out most powerfully in the plane of the antenna and in the direction opposite to that in which the free end pointed.

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  • Also he showed that if such an antenna had its horizontal part swivelled round into various directions the current created in a distant receiver antenna varied with the azimuth, and when plotted out in the form of a polar curve gave a curve of a peculiar figure-of-8 shape.

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  • 1 The mathematical theory of this antenna was given by J.

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  • Marconi also showed that if such a bent receiving antenna was used the greatest oscillations were created in it when its insulated end pointed directly away from the sending station.

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  • with wireless telegraph transmitters, in which the oscillatory discharge of a condenser is used to create oscillations in an antenna, labours under the disadvantage that the time occupied by the oscillations is a very small fraction of the total time of actuation.

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  • The antenna is connected either directively or inductively with the circuit.

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  • At the receiving end are a similar antenna and resonant circuit, and a telephone is connected across one part of the latter through an automatic interrupting device called by Poulsen a " ticker."

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  • One important measurement is that of the wave-length emitted from an antenna.

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  • This helix is presented or held near to the antenna, and the length of it shortened until oscillations of the greatest intensity are produced in the helix as indicated by the use of an indicator of fluorescent paper.

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  • 2 In Donitz's wave meter a condenser of variable capacity is associated with inductance coils of various sizes, and the wave meter is placed near the antenna so that its inductance coils have induced currents created in them.

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  • If, then, a long copper bar which forms part of this circuit is placed in proximity to the transmitting antenna and the handle moved, some position can be found in which the natural time period of the cymometer circuit is made equal to the actual time period of the telegraphic antenna.

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  • The neon tube glowed when it was in resonance with the wireless telegraph antenna.

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  • The beetles are fierce Antenna of Larva of Gyrinus.

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  • b, Antenna of male; c, antenna swollen tail-ends black with the contained food-material, are often dug up in numbers in well-manured fields.

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  • In these forms, however, the third joint is really a complex, which in many families bears in addition a jointed bristle (arista) or style, representing the terminal joints of the primitive antenna.

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  • Function of receive antenna is extraction energy from electromagnetic field.

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  • Antenna has several important parameters: resonant frequency,gain, impedance, aperture or radiation pattern, efficiency and bandwidth, polarization.

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  • Basic antenna types:

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  • AI, Second antenna.

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  • A, lateral surface view of an adult female: a, median ventral appendage; b, median dorsal appendage; c, distal ventro-lateral appendage; d, dorso-lateral appendage; f, dorsal antenna; g," chin "; x', cephalotroch.

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  • G, enlarged view of the antenna f.

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  • But the proximal pair are often fused into a single median antenna (supplied, however, by two nerves), and in one case at least the distal pair may be similarly fused.

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  • The extraing to foot of rotifers; at, median blastoporic opening of antenna, united by a nerve to br, brain the cloaca leads us to a (letter omitted in B); bl, bladder, re ver y different view, which ceiving ramified kidney in B, C, D; finds negative support f, foot, and f.g, its cement-gland;.

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  • - a, Microcodon clavus, showing corona, lateral antennae and jointed foot; b, Rhinops vitrea, corona from below, showing proboscidiform extension containing eyes; c, Philodina megalotrocha; d, head of Rotifer macroceros, postero-ventral view, showing lobes of corona, and antero-dorsal median antenna, telescopic with setae; e, Rotifer (Actinurus) neptunius, showing head with retracted corona, and protruded dorsal proboscis bearing median antenna, and telescopic foot with toes and spurs; f.

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  • Bdelloidaceae; foot with two toes and accessory spurs or a simple perforated disk; body telescopic at either end, with an antero-dorsal proboscis ending in a ciliate cup and bearing the proximal antenna; corona usually bilobed, very wheel-like.

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  • (I) first antenna; (6) tergum; (2) compound (7) biramous eye; feet; (3) liver; (8) carina; (4) simple eye; (9) cement (5) scutum; gland.

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  • The antennae of these weevils are short and end in a knob; those of the Longicorns are very much larger, but the weevil-like look is produced by the presence of a knob-like swelling upon the third joint, the terminal portion of the antenna being so extremely fine as to be almost invisible.

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  • a, Antenna or feeler.

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  • an, Antenna.

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  • 3, antenna.

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  • When the eye-stalk is removed from a living lobster or prawn, it is found that under certain conditions a many-jointed appendage like the flagellum of an antennule or antenna may grow in its place.

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  • While little importance is to be given to such characters as the unsegmented body, the small number of limbs and the absence of a shell-fold and of paired eyes, it has, on the other hand, preserved archaic features in the form of the limbs and the masticatory function of the antenna.

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  • dibular hemignaths is the second of Ant, Antenna or tactile ten the whole series.

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  • ant, Antenna.

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  • This may be filiform or brush-like or lamellate when it is an antenna or palp; a simple spike (walking leg of Crustacea, of other aquatic forms, and of Chilopods and Diplopods); the terminal joint flattened (swimming leg of Crustacea and Gigantostraca); the terminal joint provided with two or with three recurved claws (walking leg of many terrestrial forms - e.g.

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  • It appears from observation of the embryo that whilst the first prosthomere of Centipedes has its appendages reduced and represented only by eye-patches (as in Arachnida, Crustacea and Hexapoda), the second has a rudimentary antenna, which disappears, whilst the third carries the permanent antennae, which accordingly correspond to the second antennae of Crustacea, and are absent in Hexapoda.

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  • At, Antenna; d, dorsal projection; p.s., praeoral somite.

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  • The accessories include a mag mount type whip antenna with several meters of coaxial cable.

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  • Range is limited by: a) How far the transmitting antenna can effectively see.

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  • In 1937 another radio engineer, Grote Reber, began work with a parabolic reflector antenna 9.7 m in diameter.

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  • Obviously with with Ridge Hill being west, and Sutton Coldfield being north, what I needed was an omnidirectional antenna.

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  • The smallest stand-alone O2 site appears to be a pole with a single omni-directional antenna on the top, similar to the Vodafone design.

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  • The detachable antenna is easy to lose and it would be better with a solid one.

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  • antenna tuner being cut away.

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  • antenna connector.

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  • antenna coupler.

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  • antenna radiation (normal to the plane of the loop) will be polarized parallel to the short sides of the loop.

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  • antenna array.

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  • This is achieved using a specially designed splitter box to feed each dipole antenna with the correct RF signal phase.

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  • A high-gain antenna can boost wireless coverage on a single floor.

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  • All antennas built-in: telescopic antenna for FM and SW; internal ferrite bar antenna for AM.

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  • If this is the case you may need to purchase an additional re-radiating antenna, price £ 69.95 inc vat for optimum performance.

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  • The Flag Officer's Pennant is just visible below the radar antenna.

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  • aperture antenna) somewhat smaller than the physical area.

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  • The post mounting clamp supplied enables the antenna to be fixed to a suitable horizontal or vertical post of up to 20mm diameter.

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  • Connections are also available for external loud speaker and the Icom automatic antenna coupler.

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  • The main function of the antenna coupler is to provide a link to an external antenna.

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  • During our trial period the antenna was always used on the vehicle dashboard with no adverse effects.

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  • dielectric constant substrates the slot antenna can be used at the various mobile communication bands.

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  • This is the simplest type of antenna, a half wave dipole.

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  • dipole antenna elements.

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  • It might use a small dish antenna bought mail-order and some parts picked up at a surplus store.

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  • dousea result, like a classic dousing rod, very slight subconscious hand movements can cause wild changes in where the antenna points.

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  • Having less " capture area " is what makes this antenna less efficient.

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  • expressed in decibels, reflecting the amplification potential of a parabolic antenna or of an amplifier.

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  • ferrite bar antenna for AM.

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  • Antenna digs in... Brain experts at the Scripps Research Institute in California have come up with a novel strategy for shedding excess flab.

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  • helical antenna.

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  • This antenna is most useful in urban areas having reasonably strong signals coming from all directions and few multipath interference problems.

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  • isotropic antenna can only be approximated.

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  • A standard dipole radiation pattern is not isotropic - it looks bit like a donut with the antenna in place of the hole.

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  • rectangular loop antennas The same arguments may be used to analyze a rectangular loop antenna, whose long dimension is comparable to a half-wavelength.

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  • Description: The curved lines (generated by a computer program written by me) represent the magnetic field from an induction loop antenna.

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  • Background The notification concerns a proposal for installation of 15m high monopole and equipment cabin to accommodate 3no dipole antenna and 1no 0.6m dish.

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  • The antenna should be horizontally mounted with a clear view of 75% of the sky.

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  • These effects are examined in a 1.5 ton niobium resonant bar antenna.

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  • omnidirectional radio antenna... .

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  • The transmit antenna has low gain so can be made omnidirectional.

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  • parabolic antenna to contact Internet in both 2 directions.

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  • The VHF antenna is a cylindrical paraboloid of dimension 40 x 120 meters, in four sections.

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  • radar antenna.

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  • radomes in each external wing tank nose, numerous antenna above and below fuselage.

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  • radome antenna is particularly suited for mast installations.

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  • receivers antenna is considered beneficial.

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  • satellite dishg antenna is the familiar offset satellite TV type dish.

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  • section of website for more details or contact your local MEDIA Desk / Antenna for more details.

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  • Please see funding section of website for more details or contact your local MEDIA Desk / Antenna for more details.

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  • Its design conceals the antenna inside a smoothly contoured form that conveys a crisp, business-like sense of style.

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  • sonar transducer and GPS antenna can be mounted on a pole and temporarily attached to the boat's stern.

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  • The feed beam completely illuminates the reflector antenna without too much spillover.

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  • There are 4 pi steradians in a complete surrounding surface of the antenna.

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  • Furthermore, by using high dielectric constant substrates the slot antenna can be used at the various mobile communication bands.

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  • website for more details or contact your local MEDIA Desk / Antenna for more details.

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  • whip antenna with several meters of coaxial cable.

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  • yagi (antenna)in lobe of a single yagi is fairly wide, tilting did not help much.

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  • yagi (antenna)ve talk was followed by an informative and thought provoking talk on yagi antenna construction for the 1.2 and 2.3GHz bands.

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  • yagi (antenna) find your exact yagi design, you should be able to find something comparable as a guide.

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  • yagi (antenna)e this: 1. Enter details of source yagi construction.

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  • yagi (antenna)2m was 150W into a 7 element yagi.

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  • It has sometimes been claimed that Edison's proposed elevated plates anticipated the subsequent invention by Marconi of the aerial wire or antenna, but it is particularly to be noticed that Edison employed no spark gap or means for creating electrical high frequency oscillations in these wires.

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  • This elevated conductor is now called the antenna, aerial wire, or air wire.

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  • One end of the sensitive tube was then connected to the earth and the other end to an antenna or insulated elevated conductor A2.

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  • 38 6), the insulated wires or plates being upheld by masts, its operation is as follows: - When the key in the primary circuit of the induction coil is pressed the transmitting antenna wire is alternately charged to a high potential and discharged with the production of high frequency oscillations in it.

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  • This process creates in the space around electric waves or periodic changes in electric and magnetic force round the antenna wire.

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  • The antenna wire, connected to one spark ball of the induction coil, must be considered to form with the earth, connected to the other spark ball, a condenser.

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  • This periodic distribution in time and space constitutes an electric wave proceeding outwards in all directions from the sending antenna.

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  • If we consider the lines of magnetic force in the neighbourhood of the receiving antenna wire we shall see that they move across it, and thus create in it an electromotive force which acts upon the coherer or other sensitive device associated with it.

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  • At the receiving station he connected, as stated, one end of the sensitive tube to earth and the other to the antenna, and improved and applied a device of Popoff for automatically tapping the tube after each electric impact had rendered it conductive.

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  • Instead of inserting the sensitive tube between the receiving antenna and the earth, he inserted the primary coil of a peculiar form of oscillation transformer and connected the terminals of the tube to the secondary circuit of the transformer.

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  • It was seen that the effect of the impact of the incident electric waves upon the vertical receiving wire was to create in it electrical oscillations, or in other words, high frequency alternating electric currents, such that whilst the potential variations were a maximum at the top or insulated end of the antenna the current at that point was zero and at the base the potential variation was zero and the current amplitude a maximum.

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  • Hence devices for detecting the oscillations in the antenna are merely very sensitive forms of ammeter and voltmeter.

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  • It was also recognized that what is required at the transmitting end is the establishment of powerful electric oscillations in the sending antenna, which create and radiate their energy in the form of electric waves having their magnetic force component parallel to the earth's surface and their electric component perpendicular to it.

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  • First as regards the transmitting part, one essential element is the antenna, aerial, or air wire, which may take a variety of forms. It may consist of a single plain or stranded copper wire upheld at the top by an insulator from a mast, chimney or building.

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  • In any case the antenna serves as one surface of a condenser, the other surface of which is the earth.

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  • This condenser is charged electrically and then suddenly discharged and violent electrical oscillations are set up in it, that is to say, electricity rushes to and fro between the antenna and the earth.

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  • This creates rapid variations in electric and magnetic force round the antenna and detaches energy from it in the form of an electric wave.

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  • The antenna has at one moment a static electrical charge distributed upon it, and lines of electric force stretch from it to the surrounding earth.

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  • These static and kinetic conditions succeed each other rapidly, and the result is to detach or throw off from the antenna semi-loops of electric force, which move outwards in all directions and are accompanied by expanding circular lines of magnetic force.

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  • This strain corresponds to the electrical charging of the antenna.

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  • This corresponds to the electrical discharge of the antenna, and the subsequent string vibrations to the electrical vibrations.

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  • There are three ways in which the antenna may be charged (i) It may be separated from the earth by a pair of spark balls which are connected respectively to the terminals of an induction coil or transformer, or other high tension generator.

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  • If these spark balls are set at the right distance, then when the potential difference accumulates the antenna will be charged and at some stage suddenly discharged by the discharge leaping across the spark gap. This was Marconi's original method, and the plan is still used under the name of the direct method of excitation or the plain antenna.

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  • Braun suggested in 1898 that the oscillatory discharge of a Leyden jar should be sent through the primary coil of a transformer and the secondary coil should be interposed between the antenna and an earth connexion.'

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  • Over the coil of one turn is wound a secondary circuit of 5 or to turns, of which one end is connected to the earth through a variable inductance and the other end to an antenna or radiating wire A (see fig.

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  • D and spark gap, has the same natural time period of oscillation as the open circuit consisting of the antenna, secondary coil and adjustable inductance.

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  • When this is the case, if discharges are made across the spark gap oscillations are excited in the closed circuit, and these induce other syntonic oscillations in the antenna circuit.

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  • Fleming devised an arrangement in which a multiple transformation takes place, two oscillation circuits being interlinked inductively, and the last one acting inductively on the open or antenna circuit.

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  • Stone similarly devised a multiple inductive oscillation circuit with the object of forcing on the antenna circuit a single oscillation of definite frequency.'

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  • wave motion the wave-length A is connected with the frequency n and the velocity of propagation v by the relation v=nA, it follows that from such an inductively coupled tuned antenna electric waves of two wave-lengths are sent out having lengths X and such that A = (1 - k) and / (1 ±k), where A is the natural wave-length.

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  • (iii) The antenna may be direct-coupled to the closed oscillatory circuit in the manner suggested by F.

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  • One end of the inductance coil is connected to the earth, and some other point on the closed condenser circuit to an antenna of appropriate length.

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  • When oscillations are created in the closed circuit syntonic oscillations are created in the antenna and electric waves radiated from it (fig.

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  • In practical wireless telegraphy the antenna is generally a collection of wires in fan shape upheld from one or more masts or wooden towers.

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  • Sometimes the prolongations of these wires are carried horizontally or dipped down so as to form an umbrella antenna (fig.

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  • If the direct coupling is adopted then the lower end of the antenna is connected directly to the condenser circuit.

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  • In one of these ways the oscillations can be created or stopped at pleasure in the radiating antenna, and hence groups of electric waves thrown off at will.

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  • In the case of the plain or directly excited antenna the oscillations are highly damped, and each train probably only consists at most of half a dozen oscillations.

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  • The reason for this is that the capacity of a simple antenna is very small - it may be something of the order of 0.0002 of a microfarad - and hence the energy stored up in it even under a high voltage is also small.

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  • If, however, the antenna is inductively or directly coupled to a condenser circuit of large capacity then the amount of energy which can be stored up before discharge takes place is very much greater, and hence can be drawn upon to create prolonged or slightly damped trains of waves.

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  • This consists of a receiving antenna similar to the sending antenna, and in any wireless telegraph station it is usual to make the one and the same antenna do duty as a receiver or sender by switching it over from one apparatus to the other.

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  • The electric waves coming through space from the sending station strike against the receiving antenna and set up in it high frequency alternating electromotive forces.

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  • To detect these currents some device has to be inserted in the antenna circuit or else inductively connected with it which is sensitive to high frequency currents.

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  • In the early experiments Marconi connected the sensitive tube in between the receiving antenna and the earth plate, but, as already mentioned, in subsequent forms of apparatus he introduced the primary coil of a peculiar form of oscillation transformer into the antenna circuit and connected the ends of the sensitive tube to the terminals of the secondary circuit of this " jigger " (fig.

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  • 2 The tube provided with certain screw adjustments had a single cell and a telephone placed in series with it, and one end of the tube was connected to the earth and the other end to a receiving antenna.

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  • It was then found that when electric waves fell on the antenna a sound was heard in the telephone as each wave train passed over it, so that if the wave trains endured for a longer or shorter time the sound in the telephone was of corresponding duration.

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  • The wheel was connected to a receiving antenna and the mercury to earth or to an equivalent balancing capacity.

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  • When electric waves fell on the antenna they caused the mercury-steel junction to become conductive during the time they endured, and the siphon recorder therefore to write signals consisting of short or long deflexions of its pen and therefore notches of various length on the ink line drawn on the strip of telegraphic tape.

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  • When used as a receiver for wireless telegraphy Marconi inserted the oscillation coil of this detector in between the earth and a receiving antenna, and this produced one of the most sensitive receivers yet made for wireless telegraphy.

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  • If, however, one electrode of this cell is connected to the earth and the other to a receiving antenna and electric waves allowed to fall on the antenna, the oscillations passing through the electrolytic cell will remove the polarization and L temporarily decrease the resistance of the cell.

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  • To one of these sets of fine wires an antenna A and earth connexion E is added (fig.

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  • Such an oscillation valve was first used by Fleming as a receiver for wireless telegraph purposes in 1904 as follows: - In between the receiving antenna and the earth is placed the primary coil of an oscillation transformer; the secondary circuit of this transformer contains a galvanometer in series with it, and the two together are joined between the external negative terminal of the carbon filament of the above-described lamp and the insulated platinum plate.

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  • When this is the case oscillations set up in the antenna will cause a continuous current to flow through the galvanometer, the lamp acting as a valve to stop all those electric oscillations in one direction and only permit the opposite ones to pass (fig.

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  • If a simple receiving antenna as above described is set up with an oscillation-detecting device attached to it, we find that it responds to incident electric waves of almost any frequency or damping provided that the magnetic force of the wave is perpendicular to the antenna, and of sufficient intensity.

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  • - A, antenna; P S, jigger or oscillation transformer; C, condenser; 0, Fleming oscillation valve; B, working battery; T, telephone; R, rheostat; E, earth-plate.

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  • an antenna of suitable capacity and inductance to a nearly closed electric circuit consisting of a condenser of large capacity, a spark gap and an inductance of low resistance.

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  • When oscillations are excited in this last circuit they communicate them to the antenna provided this last circuit is tuned or syntonized to the closed circuit, and the radiating antenna has thus a large store of energy to draw upon and can therefore radiate prolonged trains of electric waves.

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  • Over this primary is wound a secondary circuit of five to ten turns which has one end connected to the earth through a variable inductance coil and the other end to an antenna.

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  • These two circuits are syntonized so that the closed or condenser circuit and the open or antenna circuit are adjusted to have, when separate, the same natural electrical time of vibration.

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  • The receiving arrangement consists of an antenna which is connected to earth through the primary coil of an oscillation transformer and a variable inductance.

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  • Marconi exhibited in October 1900 this apparatus in action, and showed that two or more receivers of different tunes could be connected to the same antenna and made to respond separately and simultaneously to the action of separate but tuned transmitters.

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  • At a later date a syntonic system comprising, as above stated, an antenna directly coupled to a resonant closed circuit was put into operation by Lodge and Muirhead, and much the same methods have been followed in the system known as the Telefunken system employed in Germany.

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  • Slaby paid considerable attention to the study of the phenomena connected with the production of the oscillations in the antenna.

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  • He showed that in a simple Marconi antenna the variations of potential are a maximum at the insulated top and a minimum at the base, whilst the current amplitudes are a maximum at the top earthed end and zero at the top end.

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  • He therefore saw that it was a mistake to insert a potential-affected detector such as a coherer in between the base of the antenna and the earth because it was then subject to very small variations of potential between its ends.

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  • He overcame the difficulty by erecting a vertical earthed receiving antenna like a lightning rod and attached a lateral extension to it at a yard or two above the earthed end.

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  • The oscillations set up in the vertical antenna excited sympathetic ones in the lateral circuit provided this was of the proper length; and the coherer was acted upon by the maximum potential variations possible.

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  • Braun showed that oscillations suitable for the purposes of electric wave creation in wireless telegraphy could be set up in a circuit consisting of a Leyden jar or jars, a spark gap and an inductive circuit, and communicated to an antenna either by inductive or direct coupling (Brit.

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  • When the methods for effecting this had been worked out practically it finally led to the inventions of Slaby, Braun and others being united into a system called the Telefunken system, which, as regards the transmitter, consisted in forming a closed oscillation circuit comprising a condenser, spark gap and inductance which at one point was attached either directly or through a condenser to the earth or to an equivalent balancing capacity, and at some other point to a suitably tuned antenna.

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  • The receiving arrangements comprised also an open or antenna circuit connected directly with a closed condenser-inductance circuit, but in place of the spark gap in the transmitter an electrolytic receiver was inserted, having in connexion with it as indicator a voltaic cell and telephone.

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  • In the same way the arrangements finally elaborated by Lodge and Muirhead consisted of a direct coupled antenna and nearly closed condenser circuit, and a similar receiving circuit containing as a detector the steel wheel revolving on oily mercury which actuated a siphon recorder writing signals on paper tape.

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  • All of them make use of Marconi's antenna in some form both at the transmitting and at the receiving end, all of them make use of an earth connexion, or its equivalent in the form of a balancing capacity or large surface having capacity with respect to the earth, which merely means that they insert a condenser of large capacity in the earth connexion.

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  • All of them couple the transmitting antenna directly or inductively to a capacity-inductive circuit serving as a storage of energy, and all of them create thereby electric waves of the same type moving over the earth's surface with the magnetic force of the wave parallel to it.

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  • Up to that time an induction coil known as a ro-inch coil had sufficed for spark production, but it was evident that much more power would be required to send electric waves across the Atlantic. Transformers were therefore employed taking alternating electric current from an alternator driven by an oil or steam engine, and these high tension transformers were used to charge condensers and set up powerful oscillations in a multiple antenna.

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  • The first antenna employed consisted of 50 bare copper wires 200 ft.

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  • Subsequently this antenna was enlarged, and four wooden lattice towers were built, 215 ft.

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  • apart, sustaining a conical antenna comprised of 400 wires (see G.

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  • At St John's in Newfoundland he erected a temporary receiving antenna consisting of a wire 400 ft.

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  • A vertical transmitting antenna sends out its waves equally in all directions, and these can be equally detected by a suitable syntonic or other receiver at all points on the circumference of a circle described round the transmitter.

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  • 771818) to employ a receiving antenna consisting of vertical wires held in a frame which could be swivelled round into various positions and used to locate the position of the sending station by ascertaining the position in which the frame must be placed to create in it the maximum oscillatory current.

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  • He showed that if an antenna were constructed with a short part of its length vertical and the greater part horizontal, the lower end of the vertical part being earthed, and if oscillations were created in it, electric waves were sent out most powerfully in the plane of the antenna and in the direction opposite to that in which the free end pointed.

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  • Also he showed that if such an antenna had its horizontal part swivelled round into various directions the current created in a distant receiver antenna varied with the azimuth, and when plotted out in the form of a polar curve gave a curve of a peculiar figure-of-8 shape.

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  • 1 The mathematical theory of this antenna was given by J.

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  • Marconi also showed that if such a bent receiving antenna was used the greatest oscillations were created in it when its insulated end pointed directly away from the sending station.

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  • with wireless telegraph transmitters, in which the oscillatory discharge of a condenser is used to create oscillations in an antenna, labours under the disadvantage that the time occupied by the oscillations is a very small fraction of the total time of actuation.

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  • The antenna is connected either directively or inductively with the circuit.

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  • At the receiving end are a similar antenna and resonant circuit, and a telephone is connected across one part of the latter through an automatic interrupting device called by Poulsen a " ticker."

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  • Wien's method of impact excitation by employing a form of spark gap which quenches the primary discharge instantly and excites the free oscillations in the antenna by impact or shock.

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  • One important measurement is that of the wave-length emitted from an antenna.

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  • If therefore we can measure the frequency of the oscillations in an antenna we are able to tell the wave-length emitted.

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  • This helix is presented or held near to the antenna, and the length of it shortened until oscillations of the greatest intensity are produced in the helix as indicated by the use of an indicator of fluorescent paper.

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  • 2 In Donitz's wave meter a condenser of variable capacity is associated with inductance coils of various sizes, and the wave meter is placed near the antenna so that its inductance coils have induced currents created in them.

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  • If, then, a long copper bar which forms part of this circuit is placed in proximity to the transmitting antenna and the handle moved, some position can be found in which the natural time period of the cymometer circuit is made equal to the actual time period of the telegraphic antenna.

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  • The neon tube glows with a bright orange light when the adjustments of the cymometer circuit are such that it is in resonance with the wireless telegraph antenna.

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  • The beetles are fierce Antenna of Larva of Gyrinus.

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  • b, Antenna of male; c, antenna swollen tail-ends black with the contained food-material, are often dug up in numbers in well-manured fields.

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  • In these forms, however, the third joint is really a complex, which in many families bears in addition a jointed bristle (arista) or style, representing the terminal joints of the primitive antenna.

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  • The movements of the pollen-masses may readily be seen with the naked eye by thrusting the point of a needle into the base of the anther, when the disks adhere to the needle as they would do to the antenna of an insect, and may be withdrawn.

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  • "Antenna, device, destine to receiving or transmitting electromagnetic waves.

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  • Function of receive antenna is extraction energy from electromagnetic field.

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  • Transmit antenna convert energy of generator into radiation of electromagnetic waves.

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  • Antenna has several important parameters: resonant frequency,gain, impedance, aperture or radiation pattern, efficiency and bandwidth, polarization.

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  • Basic antenna types:

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  • AI, Second antenna.

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  • A, lateral surface view of an adult female: a, median ventral appendage; b, median dorsal appendage; c, distal ventro-lateral appendage; d, dorso-lateral appendage; f, dorsal antenna; g," chin "; x', cephalotroch.

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  • G, enlarged view of the antenna f.

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  • But the proximal pair are often fused into a single median antenna (supplied, however, by two nerves), and in one case at least the distal pair may be similarly fused.

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  • The extraing to foot of rotifers; at, median blastoporic opening of antenna, united by a nerve to br, brain the cloaca leads us to a (letter omitted in B); bl, bladder, re ver y different view, which ceiving ramified kidney in B, C, D; finds negative support f, foot, and f.g, its cement-gland;.

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  • - a, Microcodon clavus, showing corona, lateral antennae and jointed foot; b, Rhinops vitrea, corona from below, showing proboscidiform extension containing eyes; c, Philodina megalotrocha; d, head of Rotifer macroceros, postero-ventral view, showing lobes of corona, and antero-dorsal median antenna, telescopic with setae; e, Rotifer (Actinurus) neptunius, showing head with retracted corona, and protruded dorsal proboscis bearing median antenna, and telescopic foot with toes and spurs; f.

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  • Bdelloidaceae; foot with two toes and accessory spurs or a simple perforated disk; body telescopic at either end, with an antero-dorsal proboscis ending in a ciliate cup and bearing the proximal antenna; corona usually bilobed, very wheel-like.

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  • (I) first antenna; (6) tergum; (2) compound (7) biramous eye; feet; (3) liver; (8) carina; (4) simple eye; (9) cement (5) scutum; gland.

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  • The antennae of these weevils are short and end in a knob; those of the Longicorns are very much larger, but the weevil-like look is produced by the presence of a knob-like swelling upon the third joint, the terminal portion of the antenna being so extremely fine as to be almost invisible.

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  • a, Antenna or feeler.

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  • an, Antenna.

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  • 3, antenna.

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  • When the eye-stalk is removed from a living lobster or prawn, it is found that under certain conditions a many-jointed appendage like the flagellum of an antennule or antenna may grow in its place.

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  • While little importance is to be given to such characters as the unsegmented body, the small number of limbs and the absence of a shell-fold and of paired eyes, it has, on the other hand, preserved archaic features in the form of the limbs and the masticatory function of the antenna.

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  • dibular hemignaths is the second of Ant, Antenna or tactile ten the whole series.

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  • ant, Antenna.

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  • This may be filiform or brush-like or lamellate when it is an antenna or palp; a simple spike (walking leg of Crustacea, of other aquatic forms, and of Chilopods and Diplopods); the terminal joint flattened (swimming leg of Crustacea and Gigantostraca); the terminal joint provided with two or with three recurved claws (walking leg of many terrestrial forms - e.g.

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  • It appears from observation of the embryo that whilst the first prosthomere of Centipedes has its appendages reduced and represented only by eye-patches (as in Arachnida, Crustacea and Hexapoda), the second has a rudimentary antenna, which disappears, whilst the third carries the permanent antennae, which accordingly correspond to the second antennae of Crustacea, and are absent in Hexapoda.

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  • At, Antenna; d, dorsal projection; p.s., praeoral somite.

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  • Dielectric radomes in each external wing tank nose, numerous antenna above and below fuselage.

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  • The low weight and compact radome antenna is particularly suited for mast installations.

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  • The antenna cables should be located away from direct sunlight, while temperature control of the receivers antenna is considered beneficial.

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  • The antenna rotated at 4 rpm and the transmissions broke through on every television set for miles around !

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  • The receiving antenna is the familiar offset satellite TV type dish.

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  • Please see funding section of website for more details or contact your local MEDIA Desk / Antenna for more details.

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  • Its design conceals the antenna inside a smoothly contoured form that conveys a crisp, business-like sense of style.

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  • The sonar transducer and GPS antenna can be mounted on a pole and temporarily attached to the boat 's stern.

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  • The feed beam completely illuminates the reflector antenna without too much spillover.

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  • There are 4 pi steradians in a complete surrounding surface of the antenna.

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  • This project seeks to create antenna designs suitable for inclusion in SoC.

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  • In particular, the communication antenna on the sensor transceiver module must be carefully chosen.

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  • A badly positioned antenna masked by a main undercarriage wheel or a poorly constructed ground plane system all adversly affect system performance.

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  • The light wave talk was followed by an informative and thought provoking talk on yagi antenna construction for the 1.2 and 2.3GHz bands.

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  • Most of these type of GPS devices also have portable functions like touch-screens, internal speaker, and internal antenna.

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  • In the past, wireless adapters used a single antenna for input and a single antenna for output, resolving only one stream of each at a time, and improvements involved more powerful antennae for more efficient processing.

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  • The bride gives each guest a length of white ribbon from her bridal bouquet to tie to their car antenna before the guests drive away.

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  • Really, the only other important internal part you need to know about is the WiFi antenna, which allows you to connect to the internet for downloads and online gameplay.

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  • These trinkets can be attached to your phone through the loop of the wrist strap or the antenna ring.

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  • The stubby antenna may be a turn off for some people, but its adequate spec sheet may be enough to win over people looking for an entry-level phone.

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  • In other words, it's not a flashy antenna, a new leather pouch, or a crystal-encrusted case or skin.

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  • For example, many phones with an external "stubby" antenna allow you to loop the cord of the charm in where the antenna is.

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  • Simply unscrew the antenna, place the loop around the metal protrusion, and screw the antenna back in.

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  • Many phones these days, however, don't have the "stubby" antenna anymore, opting for an internal device to grab the cell phone signal.

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  • The receiver will typically have no display of its own and only acts as an antenna to grab the signal from GPS satellites orbiting the Earth.

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  • The BT-359 boasts SiRFStar III technology with low power draw, Bluetooth 2.0 for speedy data transfers and a built-in ceramic patch antenna.

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  • Whether you own an ultra slim RAZR or another Motorola cell phone, you can improve your reception by making use of a cell phone antenna upgrade.

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  • If the issue is your mobile phone antenna, however, you may want to consider purchasing a cell phone signal booster.

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  • An example of a "stubby" antenna can be found on the Motorola V635.

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  • To further improve their performance, it is best to place the external antenna as close to a window as possible.

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  • From the V535 to the V600, they all have a relatively rounded bottom half and a stubby antenna on top.

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  • You may find a good variety of cell phone antenna upgrades available, especially if you still have a phone with an external antenna.

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  • Although they weren't very attractive, the handsets that had an extending antenna typically had better reception than their non-extending counterparts.

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  • These larger antenna upgrades are more powerful and, thus, are better able to connect with cellular satellites.

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  • Samsung Blackjack smart phones produced between November 2006 and February 2007 were recalled as there was a problem with the internal antenna.

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  • The wireless antenna, which is used to connect to the cellular network, is right where a person's hand or fingers may be when they are holding the device.

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  • Intussusception is a condition in which the bowel telescopes into itself like a radio antenna folding up.

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  • The aliens are green, with a round head, three eyes, no nose, pointed ears and an antenna.

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  • The micro transmitter is activated by removing a cap on the watch which releases an antenna.

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  • Who knew it was really the sound of a hammer hitting a guy wire on an antenna tower!

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  • One end of the sensitive tube was then connected to the earth and the other end to an antenna or insulated elevated conductor A2.

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