US2212625A - Television antenna - Google Patents

Description

TELEVISION ANTENNA Filed Fb. 23, 1959 Inventor: HenTH P. Thomas,

b HM MMAM His ttoPT eytransmission lines.

Patented Aug. 27, 1940 TELEVISION v ANTENNA '7 Henry P. Thomas, Schenectady, N. Y., assignor to General-Electric. Company, a corporation of New York Application February 23, 1939, Serial No.257,8s 6 Claims. (01. 250-33) I My invention relates to antennas for radio transmitters, and particularly for transmitters designed for the transmission o'fa relatively Wide band of ultra high frequencyoscillations, such as employed in 'tel'e'visionj q It is an object of my invention to provide an improved television. antenna system which radiates horizontally polarized waves having a substantially circular fieldjpattern in the horizontal plane. p

It isa further object ofmy invention to provide an antenna system*for television wherein high angle radiations is reduced and the effective transmitted field strength in the horizontal plane over the circular field patternfis increased.

It is another object to provide an antenna systen for television wherein the effective transmitted field strength is increased without incur ring distortion" of the radiation pattern whenv easily provided to prevent standing waves in the In accordance with" the present invention the I foregoingand other objects are attained by the provision of an antenna comprising eight radiators or conductors defining a cubical space, the conductors being arranged 'to form two horiof the squares from an oscillation source and in such manner that no distortion occurs in any cQmponentof the'band of oscillationswhich is transmitted. r p

, ,The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method ofoperation together with further objects the single figure of which illustrates partially diagrammaticallya radio transmission system embodying my invention. In the drawing the numerals I and 2 designate respectively an antenna arranged in accordance with my invention and a transmitter for supplying oscillations thereto, the transmitter, which may be of kilowattpower, being arranged,-for example, .to supply oscillations for" television transmission in the four and one half meter band. The band width may be ofthe usual order, of five megacycle'a'for example;

conductorsi to lo arranged to form two iden tical squares [I and 12 open at the corners, one square directly above the other and the squares spaced apart a distance equal approximately to the length of one of the conductors or'to the length of one side of the squares. The conductors 3 .to in are preferably constituted by hollow bars of conductive material, such as copper, which in the present embodiment may be four inches in outside diameter and approximately one half wave length of the transmitted Wave in length, in the present instance approximately seven feet.

To supply the antenna from the source,2, adjacent pairs of conductors 3 and 4 and 5 and 6 of one square H are connected respectively at the corners l3 and I4 thereof to the corresponding pairs of conductors l and B and 9 and ill of the other square l2 at the corners l5 and It thereof. For this purpose a pair of leads l! are connected respectively between the extremities of the par- 'allel conductors 3 and I and between theex tremities'of the parallel conductors 5 and 9,*'and' a pair of leads ii? are connected between the extremities of the parallel conductors e and 8 and between the extremities of the parallel conductors t and iii. A pairof bridging leads l9 and connect respectively the midpoints 2i and 22-of the pairs of leads l1 and I8, and a pair Inf of concentric lines 23 and M constituting a transmission line 25 connect respectively the midpoints 26 and 2? of the bridging leads l3 and 20 to the oscillation source 2.

The transmission means between source 2 and tion of the bridging leads l9 and 2B, and the transmission line 29 formed by a half section of the leads I! and 18. To prevent standinggwaves in this transmission means the two adjacent convductors, 3 and 4 in the present case, and the transmission line'sections 29, 28 and 25are so dimensioned and arranged that the impedance of the two adjacent conductors, 3 aud t, equals the surge impedance of section 29, the impedance of section 28 is equal to one half the impedance of section 29, and the impedance of transmission line 25 1s equal to one half theimpedance of section 2 8. The same constants hold for the transmission means from source 2 to the other corners l4, l5 and IS, the impedance in general being the same for the transmission means connecting source 2 to each of thepairs of conductors 3and 4, 5 and 6,1 and 8, and Sand 10. I Y

In operation of the transmission "system illustratedin the drawing, the Wide band of television frequencies being impressed, at'opposite corners .l3 and I4, and l5 and lBpon the'horizontal squares H and I2, currentsfiow in the antenna- The antenna I comprises eight radiators or which are of like phase in all of the conductors 3 to ID, as indicated by the arrows. Since the conductors in the horizontal squares are excited cophasally, the radiated energy is horizontally polarized'and the horizontal field pattern is of approximately circular'form. Since the twoi dentical horizontal squares I! and I2 are spaced vertically approximately a half wave length'of the transmitted oscillations, the substantially circular horizontal beam from the antenna is substantially flattened, the'eii'ective strength of of saidvertical leads extending between said two the ground signal being therefore substantially increased over that of the ground signal which would be provided by a single square.

In the embodiment of the invention illustrated tion. It is to be understood, however, that the invention is susceptible of various changes and modifications and that by the appended claims I intend to cover any such modifications as fall within the true spirit and scope of my invention; What I claim as new and desire to secure-by Letters Patent of the United States is:

1. In a transmission system comprising a source of oscillations, an antenna comprising eight cone ductors arranged to form two horizontal squares open at the corners and one directly abovethe other, the length of saidconductors and the 'distance between said squares being approximately equal to a half: wave length of said oscillations, two pairs of vertical leads connectingrespe'ctlvely at two opposite corners of said squares the extremities of opposite conductors of one square. to the extremities ofthe corresponding opposite conductors of the other square, and means to connect one terminal of said source to the mid points of one of said pairs and to connect the other terminal of said source to the midpoints of the other pair. I

2. In a transmission system comprising a source of oscillations, an antenna comprising a set of four conductors arranged to form a horizontal square open at the corners, a second set of four conductors arranged to form a second horizontal square open at the corners directly above said first square and spaced therefrom a distance approximately equal to a side of said squares, two pairs of. vertical leads, connecting respectively at two opposite corners of said squares the extremities of opposite conductors of one square to the extremities of the corresponding opposite conductors of the other square, a pair of leads bridging respectively the midpoints of said pairs L of vertical leadspand means to'connect the opposite terminals of said sourcerespectively to the midpoints of said bridging leads,

3 In atransmission system comprising an os-. cillation source, an antenna comprising two sets of conductors, each sethaving four conductors arranged in a square open at the corners, said squares being equal and spaced apartone above the other a distance approximately equal to the length of one of saidconductorstwo pairs ofvertical leads connecting respectively at two opposite corners of said squares the extremities of opposite conductors of one square to the extremities of the correspondingiopposite conductors of theother square, and means to connect the terminals of said source respectively to the midpoints of said pairs, said conductors and said vertical leads being so arranged that the impedance of any given adjacent two of said conductors connected to the corresponding section conductors and said connecting means is equal to the surge impedance of said section.

4. In a transmissionsystem comprising a source of oscillations, an antenna comp-rising eight conductors arranged to form two horizontal squares spaced apart a distance approximately equal to aside of said squares,.two pairs of vertical leads connecting respectively opposite conductors oi one square to the corresponding opposite conductors of the other squarejleads bridging the midpoints of said pair of vertical leads, and a transmission line connecting said source to the midpoints of said bridging leads, said conductors, vertical leads, bridging leads and transmission line being so arranged that the impedance of any given two of said conductors connected to the corresponding section of said vertical leads is equal to the surge impedance of said section, the impedance of that section of said bridging leads between the connection point thereto of said ing spaced apart a distance approximately equal to a side of said squares, means to supply current from said source to said conductors at two opposite corners of one square and at two opposite corners of the-other squaredirectly, above said first-named corners, said means being so arranged that the current in all of said conductors is of like phase,. said means comprising connection-means between said source and said "four corners so arranged that the impedance of said connectionmeans is the same between said source and, each of said corners. I

6. Ina transmission'system comprising a source of oscillations, an antenna comprising eight identical conductorsarrangedto form two horizontal squares open v at the corners, one square being directly above the other and the squares being spaced apart a distance approximately equal. to aside of said squares, means to. sup-ply current-from said source to said squares at op-' posite corners thereoi so arranged that the currents in all of said conductors are .of like phase,

saidmeans comprising two identical transmission lines each constituted by .two identical sections,

said lines connecting respectively the two oppoa site corners of one square to the two corresponding opposite corners of the;-','otl1er square, means to, connect the connection point of .thesections of one of said lines to said source, and means having-the same impedance as said last-named means to connect the connection point of the sections of the other line tosaid source;

P. moi/ms-

Images