US2700105A

US2700105A - Tv antenna array

Info

Publication number: US2700105A
Application number: US445670A
Authority: US
Inventors: Winegard John Robert
Original assignee: Winegard Co
Current assignee: Winegard Co
Priority date: 1954-07-26
Filing date: 1954-07-26
Publication date: 1955-01-18
Anticipated expiration: 1972-01-18

Description

1955 J. R. WINEGARD T. v. ANTENNA'ARRAY 2 Sheet-Sheet 1 Filed July 26, 1954 INVEN TOR. tic W12 R; (A/megar-"zf 1955 J. R. WINEGARD T. v. ANTENNA ARRAY 2 Sheets-Sheet'Z Filed July 26, 1954 INVENTOR. V 4 ,Qwme qrd W i/l United States Patent Ofiice 2,700,105 PatentedJan. 18, 1.955

TV ANTENNA ARRAY- John Robert Winegard, Burlington, Iowa,. assignor. to Winegard Company, Burlington", Iowa, a. corporation ofIowa Application July 26, 1954, Serial No. 445,670

9 Claims. (Cl. 250-63251) My invention relates to animproved antenna for'television reception.

Antennas for use in television-reception musthave a wide band characteristic giving good response over both the. low'frequency (54'88 megacycles) television-band and the high frequency (174216 megacycles) television band. In addition, such antennas-particularly those used in locations remotefrom television-transmitting stationsmust have a high response or gain in order-that the relatively weak signals fromthe transmitter may be effectively received.

In accordance with the disclosure of the present application, these objectives are achieved in a structure which utilizes a drivenelement in-conjunction with a coplanar director array located in front of this element. The director array consistsof dipoles approximately-onehalf wave-in length at a'f'requency inthe high frequency band and connectedtogether by a-folded transmission line. The latter acts as an inductance in the:low frequency'band to cause the dipole to act'asa simpledirector in the low frequency-bandoflesszthanone-halfwave in'length. These dipoles arespacedfromzthezdriven di pole elements and from each' other and are coplanar with the-driven element. In addition to: these dipoledirectors, theantenna includes-a series of. unitary directors located in parallel, aligned, coplanar relationship with the driven elements-and'withthe:dipole?'directors; These unitary directors are located approximately mid way between the dipole directors andl at like distances in front of the front director andfimbackof the reardi-z rector. Each of the unitary'directorsis approximately the same length as one arm: of'the dipolezdiiectorsi'and resonates as a one-*halfwaveunitata frequencysome what below the lowfrequencyend of'ltheshigh frequency band.

It is therefore a general objectofrthe presentzinvention to: provide an improved antenna: suitabler fOIi television reception.

A further object of the present iIIVCDfiOHZiSZIOrPIQVidC an improved antenna:suitableifor"televisionzreception and characterized by high: sensitivity extending over the; full television frequency range of 524-88? 'megacycles and 17 4 -216 megacycles;

Further it is' anobject of" theipresent invention to-rprovide an antenna of the above type utilizing-:an-inline construction; having. low wind. resistance; having; low cost; having minimum weight;andfhavingamacximum degree of simplicity and reliability.

Additionally; it is :an object of the'present: invention to provide an improved director system for a television. an= tenna and'eifective' over both the 48'8 megacycleband and the 174-216 .rnegacycle band.

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,.bothi as to its organization and method v of operation,.together with-furtherobjects and advantages thereof, willbestbe understood by reference-to the following description taken in connection with the accompanying drawing in which:

Figure 1 is a view in perspective of 'a'tel'evisionantenna constructed in accordance withth'e present invention.

Figure 2 is an enlarged'fragmentary top plan'viewof the support postand adjacent portions'of the antenna structure;

Figure 3 is a view-stillfurther enlargediand'showing the I central; portions of a :dipole "director and the adjacent portionsof the support bar;

Figure 4'is a view in perspective ofanother television antenna having director elements constructed inaccordance with the present invention; and,

Figure 5 is a view in perspective of' still another antenna utilizing the director elements of the present invention;

Referring nowto thew drawing, the antenna; is supported by a mounting. mast M which extends invertical direction and'is supportedby suitable means-(not shown). At thetop ofthe.mastM,.a horizontal mounting bar-'10 is -affixed by-any suitable means. In the structure shown, the bar 10 is held in place by the U'-boat 12 which is received in the bar 10 and is drawn' tight by suitable nuts 12a,'.Figure 2, to anchor themounting bar 10rigidly in place. As shown in the figures, the'various antenna elements are affixed to and supported by the bar 10;

The front driven element is shown generally at 14. This-element consists of a forwarddipole portiondefined by arms.14'a*and a rear unitary portion defined by'the continuous bar 14b. As shown, the dipole arms 14a are connected to=theunitany bar'14b by'the rearwardly extending arms 1'4'c, each of whichis connected to the di pole arm 1'4'a'at approximately the mid-point of its-length and extends' rearwardly in direction parallel to-the bar 10.v The'rear unitary bar14b is afiixed'to-the'support-bar lflbya saddle bracket 14d which embraces bar 10 and forms a partially cylindrical seatfor bar 14b. Thebar 14b is held tightly against the bracket 14d andthe latter is held tightly on bar 10 by bolt 14e-and.thumb.. nut. 14

The adjacent ends of' the dipole.14aare. joined by spacer 14g which'isof insulating material, such as Bakelite and has terminal posts 14k to receive theendsofthe open transmissionline 16 which arereceived in the. ter.- minal posts and are drawn to tight seating relation by theterminal. posts. This transmission line is held adjacent the binding posts 14h by the arm 16a which is afli'xed at one end'to the mast M and at the other end has itn insulatingsleeve 16b which receives the transmission A similar driven element 18 is located rearwardly on bar 10 in relation to the unit 14. The unit 18 is-oflike construction. using dipole arms. 18a, a unitary bar18b extending. parallel to andin line with the elements and a pain of connecting bars approximately midway on the. dipole. elements and extending parallel to the support liar l'tlbetween the. dipole elements ISaancLtheunitary rear elementlSb. The dipole elements 18a are. likewise connected attheir adjacent endsto theinsnlating spacer 18g which has binding posts 18h to. receive. theopen transmission line 20 definedby. conductorst20a and2llb which is received on the binding posts14h' at its front end and receives the binding posts 18h at its rear end.

The forwardidriven element 14 is.of such.length as.to receive most efficiently in the high frequency television band of l74-2'l6:megacycles. In this frequency. range the transmission. line 20, including the. stub portions outboard of element 18, acts as a one-half wave open line to present avery high impedance acrossthetra-nsmission line 16. The rear driven element18iisof lengthitoreceive most efiiciently in the low frequency televisionband of 54-88 megacycles. In this frequency range the transmission line 20 acts as a non-resonant line.

Rearwardlyof the unit 18; there-is provided a-reflector 22"whichconsists of a unitary'bar extending parallel'to and -in'- coplanar aligned relationship withthe'units 14 and 18. This-baris-attached to the support bar 10'by the saddle 22a and "by the anchor bolt 22b and thumb nut 220 as shown.

'Forwardly of the driven element 14 a pair of dipole directors 24 and26 respectively are provided. These directors are' carried from. the support bar 10 by the insulating

blocks

24a and 26a, respectively, each block being seated on the support bar 10 and held snugly thereon..by. a bolt 28a. Atitstop face,,each block 24a.and 26a.has-a pair of conductingclamp pieces 25,.Figure. 3, which areheld'snuglydown on thearm of the dipole 24 by bolts 28b which protrude beneath the. block. Each block 24asand 26a also'receivesthe ends of the

coupling unit

24b or 26b as the case may be, thus establishing an electrical contact between the coupling unitand the director. These coupling units are in the form of folded closed resonant lines as shown.

The arms of

dipoles

24 and 26 are made slightly shorter than the arms of dipole 14a. The

resonant lines

24b and 26b are resonant, in conjunction with the capacitance of the adjacent parts such as bar 10, at approximately the frequencyat which the

dipoles

24 and 26 are half wave in length. Thus, at these frequencies the dipole arms are effectively disconnected. However, at lower frequencies the

lines

24b and 26b do not function as resonant lines butrather as short-circuiting connections with some inductive effect thus causing the

dipoles

24 and 26 to act as unitary directors in these frequence ranges and to appear to have a somewhat lower natural resonant frequency than their physical length would indicate.

A series of three. unitary directors 29, 30, and 32 are likewise mounted on the support arm 10 in positions straddling the

dipole directors

24 and 26. As shown, these directors are mounted on the support bar 10 in the same fashion as reflector 22, that is, by the use of a saddle and an appropriate mounting bolt. The directors 29, 30, and 32 are approximately the same length as the arms of the

respective dipoles

24 and 26. Moreover, the directors 29, 30, and 32 are spaced from

dipoles

14a, 24 and 26, by approximately the same disstances so that directors 29 and 30 are substantially midway between the respective dipoles and director 32 is about the same distance in advance of the dipole 26.

In an actual television receiving antenna constructed in accordance with the present invention the following dimensions were used:

quency of about 180 megacycles).

6% inches. 25 inches.

/2 inches.

18 inches (to give an antiresonant frequency of about 180 megacycles).

Distance between dipole 26 and director 30 Length of director 30 Distance between director 30 and dipole 24 Length of resonant line 24b Distance between dipole 24 and di rector 29 7 inches. Length of director 29 25% inches. Length of dipole arms 14a 25 inches. Distance between director 29 and the parallel portions of dipole arms 14a 4 inches. Length of arms 14c 4 inches. Length of bar 14b 70 inches. Length of transmission line 20 .28 inches. Length of dipole arms 18a 38 inches. Length of bars 180 4 inches. Length of bar 18b 99 inches. Length of reflector 22 110 inches. Distance between reflector 22 and bar 181) 24 inches.

An antenna constructed in accordance with the above dimensions has been found to give good response over the entire television frequency range with an average gain of about 6 decibels over a simple dipole.

It will be observed that the antenna above described is an antenna wherein all of the antenna elements lie in a common plane. This provides a desirably low wind resistance. It also makes it possible to mount the antenna parts on the common support bar 10. In addition, the antenna is of rugged construction and is simple in design, features which contribute to its general usefulness.

In the antenna above described it has been found possible to receive all television bands without difficulty. The directional characteristics are approximately those of a dipole with a single reflector so that the antenna displays a substantial degree of directivity without being unduly critical.

1 The spacings between the various elements of the anlength to operate effectively tenna of Figure 1 may be adjusted to vary the antenna characteristics such as the impedance as seen by the transmission line 16. Within reasonable limits these spacings are not critical although for normal television E186 approximately the proportions of Figure l are preerre The characteristics of the

resonant elements

24b and 26b are greatly influenced by the capacitance eflects of the adjacent parts, particularly the support arm 10 which is of metal such as aluminum. The capacitance resulting from this arm together with the capacitance of the hardware such as the clamps 25, causes these resonant elements to resonate at a frequency considerably lower than their length would indicate. This is a highly desirable feature of the structure of the present invention since the inductive reactance of these elements in the low frequency band is lower than would otherwise be the case. As a consequence of this lower inductance the

units

24 and 26 effectively act as directors in the full 54-88 megacycle band. Were it not for this effect, the director action of these elements would be lost near the high frequency end of this band, and, indeed, these elements might even act as reflectors and defeat their purpose.

The action of the

directors

24 and 26, in conjunction with directors 29, 30 and 32 can be regarded as that of a high band director system using elements 29, 30 and 32 interposed on a low band director

system using elements

24 and 26. However, the action of the

coupling units

24b and 26b is to avoid the shielding effect otherwise associated with

directors

24 and 26 and to cause these directors to give some director action in the high frequency band. At the same time, however, the

coupling units

24b and 26b provide a degree of inductive reactance at the low frequency band and thus give rise to good director action in that band even though the length of

directors

24 and 26 would otherwise be too small at the high frequence end of that band.

Figure 4 shows an alternative antenna structure using a director system constructed in accordance with the present invention. In this system the mast M carries a support bar or boom which in turn carries reflector 122. Forwardly of the reflector there is provided a two band driven element 114 of the type de-v scribed and claimed in my copending patent application entitled Dual Band Antenna, Serial No. 446,010, filed July 27, 1954. In brief, this driven element consists of a pair of spaced coiinear dipole arms 114a of in the low frequency band. A pair of forward angled dipole elements 114b are mounted at the inboard ends of dipole elements 114a by means of the connecting and supporting arms 1140 and 114d. The entire unit is aflixed to the boom 110 by an insulating support 114e as described more particularly in the above-identified application. Transmission line 116 is connected to the inboard ends of the arms 114a as shown.

The arms 114d are so positioned on the

dipole arms

114b and 114a as to definein conjunction with the outboard portions of these dipole arms-a half wave open circuited resonant transmission line in the high frequency band. This reflects a very high impedance which causes the portions of

arms

114a and 114b inboard of arms 114d to operate substantially independently of the outboard portions in the high band, thus giving rise to action similar to that of a simple half wave dipole.

The boom 110 receives director 124 forwardly of the driven element 114. This director is like director 24, Figure 1, and includes a coupling line 124b to give the dual band action described above in connection wtih director 24. The director 129constructed like director 29, Figure 1is interposed between director 124 and the driven element 114.

In operation, the two arms of director 124 are effectively disconnected in the high frequency band and the director 129 operates as a director, while the driven element 114 operates in generally the same manner as if it consisted only of the portions inboard the arms 1140!. In the low band the director 124 operates as a director with the coupling 124b contributing more inductive reactance and the

arms

114a and 114b of the driven element operate in a manner similar to a half wave dipole.

Figure'S shows still another antenna having a director system constructed in accordance with the present inven tion. In this antenna the boom 210 carries a pair of zrnroa' es spaced low band'an'd high "bandifol'ded"dip'oies, are -11a '?14, respectively. Transmission line. H6 ''is connected to the'dipole'218 'andthrougl1 a resonant sectionf216a'to the low band dipole 21.8. 'rhessection"2l6aacts 'as' an "open one-halfwave line at the "high tban'dto decouple the low band'dipole -218Iin this'band, whereas the effect of the dipole 218 is negligible'at'thelow'band.

The director 224, constructed' like 'director'24,:Figure 1,; is .located :forwardly of "the driven elements 214 and f21'81and acts primarily to ,give director action "in' thelow "frequency band. The resonant coupler 224a contributes indu'ctance to director 224 at "the ;low' frequency band and electrically separates the'a'rms of director224 inithe thigh frequency band. .A second director 229 is located .forwardly of the director 2'24 and'is-cuttolen'gthrto act as a director in the high frequency band.

While the present invention is particularly applicable to television antenna-applications, 'it is usable generally where a high :frequency antenna must operate in two fre'quency bands, one about twice-the frequency .of the other. One such application is that of .amateur radio antennas for use in, say,' both. the 10 meter .and 210- meter .amateur bands, eitherfor transmitting or receiving.

-Itwill be noted that the directors "24, "26, 29,'30and '32.are in parallel coplanarmelation with respectto the remaining elements of the-antenna. In addition, these directors are symmetrical about the boom 10 andhence are aligned withieach other land with the remaining elements.

While I have shown and described a specific embodi- 'ment of the-present invention it will; ofxcourse,'be'-'underrstood that various modifications and-alternative constructions may-be made withoutdepart-ing from its'true .spirit rand scope. In particular, it is possible-to vary:individual :dimensions-from those shown to .accent the response'of rtlre antenna toparticular frequencies or to suppress such tresponse. These adjustments can be-smade on'a cut and ttry basis to accommodate the antenna to particular conditions or to provide a characteristic deemed superior for general use to that of the antenna as specifically described above. I therefore intend by the appended "a plurality of laterally spaced'pairs oflilredirector tile claims to cover all antennas falling within their true spirit and scope.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A television antenna to receive signals over a wide frequency band comprising in combination: a pair of coplanar parallel spaced driven units each having a forward dipole and a closely spaced rear unitary element, the dipole being connected to the unitary element by transverse conductors positioned approximately midway along each arm of the dipole; a plurality of dipole directors each having total length approximately one-half wave in length at a frequency near the low frequency end of the band located forwardly and in coplanar parallel relation with the driven units, the dipoles being spaced from each other and from the forward driven unit; antiresonant elements tuned to a frequency near the high frequency end of the band connecting the adjacent ends of the arms of the dipole directors; and unitary directors approximately one-half wave in length at the high frequency end of the band, the last mentioned directors being interposed approximately midway between the adjacent dipole directors and between the forward driven element and the adjacent first dipole director.

2. An antenna for use in receiving signals throughout the frequency range of the low frequency and high frequency television bands comprising in combination: a driven element operable to receive signals in said bands from a predetermined direction; a plurality of coplanar parallel aligned director elements located in said direction from the antenna; each of said elements being approximately one-half wave in length at the high frequency end of the high frequency band; a plurality of pairs of dipole director elements in coplanar parallel aligned relation with said first mentioned director elements, the total length of each of said last directors being approximately one-half wave in the low frequency band, the pairs of dipole director elements being interposed substantially midway between the first mentioned director elements; and resonant couplings connecting the adjacent ends of the dipole director elements, the couplings being resonant at frequencies in the high frequency band and having an inductive reactance in the low frequency band whereby in the high frequency band 'ments in parallel coplanar relationwi'th and interposed between the first director elements in 'said'directio'nfto define dipoles; and coupling elements connecting 'the 'ad- ,ja'ce'nt ends of the "directors of 'saidlastpair's, the'cou'pling elements being resonant at afrequency in the hig'hlfrequency end .of the range whereby in thehigh'ffrequency end of the range thepairs o'fdirector elementsactfi'ndividuallyas resonanttdirectors without shielding the 'first .mentioned director elements and ..at Ithe'lowifrequency endof therangethe pairs of directors actin uriisonas resonant directors.

4. In an antenna fortelevision useto receive signals in both the high 'frequencyand low (frequency television band, the improvement :comprising: a driven r element adapted to receive telcvision .signals; a unitary-director located rin-parallel-coplanar relation with thetdriven elemerit, the director being approximately.one-half wave; in length in the high :frequency -.band; a dipole director located in coplanar {parallel aligned relation with the driven element and unitary director, 'thedipole -.director having total length substantially ahalf --wave -length-in .the a low frequency television bandgr-and -a resonant trans- -mission line having a a large shunt capacitance. connecting the inboard ends of the dipole-director and-resonant tin the high frequency band, -wherebyzintthe high frequency I hand the dipole directorlact-s as atpaiiwof-individual resonant directors without zshielding-tthe-dri-ven element or unitary director and in the low frequency band the dipole director acts as a unitary resonant director.

5. A director system for a two band antenna, the director system comprising in combination: a unitary director of length to operate as a director in the high frequency band; and a dipole director in coplanar parallel aligned relation with the unitary director, the dipole director consisting of colinear dipole arms joined at their inboard ends by a coupling unit resonant in the high frequency band, the length of the dipole director being such as to give director action in the low frequency band in conjunction with the impedance of the coupling unit, whereby in the high frequency band the dipole director acts as a pair of individual resonant directors without shielding effects and in the low frequency band the dipole director acts as a unitary resonant director.

6. A director system for a two band antenna having a longitudinal support boom, the director system comprising in combination: a unitary director of length to operate as a director in the high frequency band, the unitary director being affixed in centered relation on the boom; and a dipole director mounted on the boom in coplanar parallel aligned relation with the unitary director, the dipole director consisting of dipole arms insulatingly supported in colinear relation from the boom; and a coupling unit joining the inboard ends of the dipole arms, the coupling unit comprising a closed parallel wire transmission line conductively attached to the inboard ends of the dipole arms respectively, extending in parallel relation to the boom for part of its length adjacent the dipole arms to embrace the same, and in a plane normal to the boom extending in U-shaped configuration about the boom for the remainder of its length, the coupling unit being resonant in the high frequency band in conjunction with the capacitance of the boom, the length of the dipole director being such as to give director action in the low frequency band in conjunction with the impedance of the coupling unit.

7. An antenna for television use comprising in combination: a conducting support boom; a driven element mounted on the boom in centered relation and adapted to receive signals from one direction lengthwise of the boom and over a wide range of frequencies; a plurality of parallel coplanar director elements mounted on the boom in spaced centered relation in said direction from the driven element, said elements being resonant at a frearms to embrace the same and in a plane normal to the boom extending in U-shaped configuration about the boom for the remainder of its length, each transmission line being resonant in the high frequency band in conjunction with the capacitance of the boom,

each dipole being such as to give director action in the low frequency band in conjunction with the impedance of the transmission line.

8. A television antenna to receive signals over a wide frequency band comprising in combination: a conductthe length of ing boom; a pair of coplanar parallel spaced driven units each having a forward dipole and a closely spaced rear unitary element, the dipole being connected to the unitary element by transverse conductors positioned approximately midway along each arm of the dipole, each of said driven units being mounted on the boom; a plurality of dipole directors having a pair of colinear arms insulatingly mounted on the boom, each dipole director having a total length of approximately one-half wave in length at a frequency near the low frequency end of the band and located forwardly and in coplanar parallel relation with the driven units, the dipole units being spaced from each other and from the forward driven unit; closed parallel wire transmission lines connected to the inboard ends of the dipole directors, respectively, each transmission line embracing the boom for a part of its length adjacent the dipole director and in a plane normal to the boom extending in U-shaped configuration about the boom for the remainder of its length and being tuned to a frequency near the high frequency end of the band to ,tively,

cause the dipole director arms to operate individually at the high frequency end of the band and in unison at the low frequency end of the band; and unitary directors approximately one-half wave in length at the high frequency end of band, the last directors being interposed approximately midway between the adjacent dipole directors and between the forward driven element and the adjacent first dipole director.

9. In combination, for use in a TV antenna operable over both the 54-88megacycle band and the 174-216 megacycle band: a conducting support boom; a driven element mounted on the boom and operable to receive signals from a predetermined direction in both of said bands; a dipole director comprising a pair of colinear arms insulatingly supported from the boom forwardly of the driven element with respect to said predetermined direction, the total length of the director being approximately one-half wave in the 54-88 megacycle band; and, a closed transmission line connected at its ends, respecto the dipole arms, said line straddling the boom over the part of its length adjacent the dipole arms and in a plane normal to the boom extending in U-shaped configuration about the boom over the remainder of its length, the transmission line being tuned to resonate in conjunction with the capacity of the boom in the 174-216 megacycle band to cause the dipole arms to operate as individual directors in that band.

References Cited in the file of this patent UNITED STATES PATENTS 1,745,342 Yagi Jan. 28, 1930 1,934,182 Franklin Nov. 7, 1933 2,204,175 Carter June 11, 1940 2,268,640 Brown Jan. 6, 1942 2,380,333 Scheldorf July 10, 1945 2,572,166 Lorusso Oct. 23, 1951 2,578,973 Hills Dec. 18, 1951 2,688,083 Hills Aug. 31, 1954