US2886813A

US2886813A - Directional antenna

Info

Publication number: US2886813A
Application number: US347871A
Authority: US
Inventors: Donald L Hings
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-04-10
Filing date: 1953-04-10
Publication date: 1959-05-12
Anticipated expiration: 1976-05-12

Description

May 12, 1959 HINGs 2,886,813

DIRECTIONAL ANTENNA Filed April 10, 1953 5 Sheets-Sheet 1 fF/GZ INVENTOR. DONALD L. HINGS W MM May 12, 1959 D. L. HINGS 2,886,813

DIRECTIONAL ANTENNA Filed April 10, 1953 5 Sheets-Sheet 2 HORIZONTAL VERTICAL POLARIZATION POLARIZATION I80 INVENTOR.

' DONALD L.. H/NGS FIG. 9 FIG. IO BY W M f May 12, 1959 D. L. HINGS 2,836,813

I DIRECTIONAL ANTENNA Filed April 10, 1953 5 Sheets-Sheet 5 INVENTOR.

DONALD L HIN GS United States Pa n DIRECTIONAL ANTENNA Donald L. Hings, Vancouver, British Columbia, Canada Application April 10, 1953, Serial No. 347,871

28 Claims. (Cl. 343--819) This invention relates in general to directional antennas for the higher frequencies, such as VHF, and more particularly to a multi-element antenna array having a highly directive pattern in the horizontal plane for a high gain.

At VHF frequencies, the element lengths of antennas are of a practical length for self-support. A center-fed dipole, which is one-half a wave length and horizontally polarized, has a figure 8 pattern in the horizontal plane. By using the Yagi principle of reflectors and directors, the directivity of the one-half wave dipole can be increased. The reflectors are typically spaced to the rear of the dipole approximately one-quarter wave length of the working frequency and the directors are placed in front of the dipole at one-tenth to one-third of a wave length spacing. Yagi antenna arrays are generally used on frequencies from ten megacycles to one thousand megacycles.

A plurality of director elements may be used to increase the forward gain. These directors taper in length, with shorter lengths in the front to obtain this directivity. The phase relation between the directors and dipole is obtained by cutting the director elements to a length so that they are resonant to a frequency higher than the working frequency. Similarly, the reflector element is cut to be resonant to a frequency lower than the working frequency.

An object of the invention is to provide an antenna having a directive pattern.

Another object of the invention is to provide an antenna having a high gain in the forward direction.

Another object of the invention is to provide an antenna having a relatively high front-to-back ratio.

Another object of the invention is to provide a shaded dipole constituted by a dipole element and first and second shunt elements having resonant frequencies higher and lower than the working frequency of the dipole.

Another object of the invention is to provide shunt voltage fed antenna elements on a dipole antenna element.

Another object of the invention is to provide collector elements in combination with a shaded dipole wherein the collector elements are generally linearly disposed off the ends of the shaded dipole and have a resonant length substantially on the working frequency.

Still another object of the invention is to provide an antenna array which is highly directive and disposed in a fiat plane.

Still another object of the invention is to provide an antenna array having a driven element and shunt elements each of which have coupling portions for a voltage coupling between the shunt and the driven elements which voltage coupling may be capacitive or conductive and with this voltage coupling exceeding the radiation wave coupling achieved by the space-phase relationship.

Still another object of the invention is to provide an antenna element having a physical length less than the electrical length.

"ice

Still another object of the invention is to provide a driven dipole with both series and shunt elements, with the series elements being collectors disposed off the ends of the driven dipole.

Still another object of the invention is to provide an antenna which is compact in the front-to-back dimension,, yet which has a good directivity pattern and with a good front-to-back ratio.

Other objects and a fuller understanding of this inven: tion may be had by referring to the following description A and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a plan view of a driven dipole and a rear wardly disposed single shunt element;

Figure 2 is a plan view of a driven wardly disposed shunt element;

Figure 3 is a three dimensional view of a shaded dipole constituted by a tuned driven dipole and front and rear shunt elements. M

Figure 4 is a horizontal polar diagram of a radiation pattern of the antenna of Figure 3;

Figure 5 is a plan view of another form of shaded dipole;

Figure 6 is a plan view of another form of a shaded dipole constructed from wire;

Figure 7 is a side view of a complete multi-element I antenna system; i Figure 8 is a perspective view of the antennaof Figure 7;

Figures 9 and 10 are horizontal and vertical polarization patterns of the antenna of Figures 7 and 8; and

Figure 11 is a plan view of the antenna elements in a modified form of multi-element array.

The Figure 1 shows a half wave dipole .15 which in this case is constructed of metallic tubing approximately one-half inch in diameter for use on the two hundred megacycle band, and this dipole has been constructed twenty-six inches in length. Feeders 16 are connected at the center of the dipole 15 and may be either the conventional flexible lead-in or may be the beginning of a trombone matching stub.

A rear shunt element 17 has a central U-shaped portion 18, diverging legs 19, and capacitive feet 20. The capacitive feet 20 constitute coupling portions for the shunt element 17.

Areas

21 and 22 on the dipole 15 constitute coupling portions for a voltage coupling with the rear shunt element 17.

The Figure 2 shows the dipole 15 in conjunction with a front shunt element 25. This shunt element has an intermediate portion 26 and legs 27. The intermediate portion 26 and legs 27 have generally a U-shape. Capaci-' tive feet 28 are disposed on the ends of the legs 27. The

dipole and a forfeet 28 again are coupling portions of the shunt element 25 for voltage coupling with coupling portions on the half wave dipole 15 defined by

areas

29 and 30. Figures l and 2 thus show two alternative ways of partially shading the dipole 15 by use of the

shunt elements

17 or 25.

The Figure 3 shows a three dimensional viewof a shaded dipole 31 which in this case is made of flat bar stock. The shaded dipole 31 includes a tuned dipole 32 having a matching transformer 33, a rear shunt element 34, and a front shunt element 35. The rear and front shunt elements 34- and 35 have a shape similar to the rear and

front shunt elements

17 and 25. The rear shunt element 34 has coupling portions 36, and the front shunt element has coupling portions 37.

The

dipoles

15 and 32 have been characterized as driven elements, and this is taken to mean an antenna element directly connected to some form of radio device, whether receiver or transmitter, since the antenna works equally well on both receiving and transmitting in accordance. with the usual reciprocity theorem form antennas. The

rear shunt element

17 or 34 has been tested with a dip meter while in place; and when having its optimum length, it was found that these rear shunt elements have a resonant frequency characteristic slightly lower than the resonant frequency characteristic. of the dipole or 32 which is at the working frequency. The front shunt elements and were tested with a dip meter while in place and found to have a resonant frequency characteristic higher than the working frequency. In some cases, depending upon the length of the shunt elements, the end portions thereof may actually conductively contact the

dipoles

15 or 32. Generally, however, capacitive coupling is utilized. This capacitive coupling is a form of voltage coupling which, because of its close proximity, is greater than the, space-phase coupling normally associated with Yagi directors and reflectors. With reference to Figure 3 it has been found that the spacing between the dipole 32 and the

coupling portions

36 and 37 is such that there is. approximately two to three times as. great a space at the coupling portions 37 as at the coupling portions 36. The spacing on the rear shunt element 34 was. found to be optimum at about three-eighths of an inch, and the spacing on the front element 35 was found to be optimum at about one inch. At the frequencies used, this was about .007 of a wave length and .02 of a wave length, respectively. The voltage coupling at the

coupling portions

36 and 37, because of this close spacing, is thus greater than the spacephase coupling which may be considered the radiation wave coupling. Still further, it would be observed that the physical length across the ends of any of the shunt elements is less than the electrical length. It, is believed that the impedance across the end portions of the shunt elements is. approximately equal to the impedance on the dipole, such as dipole 15, between the

areas

21 and 22, for the rear shunt element 17 and between the

areas

29 and 30 for the front shunt element 25.

The tested db gain of the antenna of Figure l was about six db gain over a straight dipole. The tested performance of the antenna of Figure 2 was found to have about three db gain over a straight dipole. The antenna of Figure 3, which is a shaded dipole, was found to have seven db over the tuned dipole 32 alone. Feed lines may, of course, be connected onto the matching transformer at the proper impedance matching point as is customary practice.

The polar diagram of Figure 4 shows the radiation pattern which is a horizontal pattern for the plan view of Figure 3. Figure 3 definitely gives a good cardioid pattern toward the. front with a front-to-back ratio of approximately 16' db. The shaded dipole of Figure 3 is thus a compact antenna array which has a high forward gain and a stillhigher front-to-back ratio.

The Figure 5 shows another form of a shaded dipole having a tubular half wave dipole 4-0 having feed points 41. A front shunt element 42 is formed from tubing and has a plurality of turns on a coil 43. The element 42 has coupling portions 44 at the ends thereof. A rear shunt element 45 is similarly constructed with a coil 46 and coupling portions 4-7. By this means the overall length of the front and rear shunt elements was reduced to only about one-eighth wave length, and the overall thickness of the shaded dipole became about onefifteenth of a wave length.

The Figure 6 shows an antenna constructed of wire such as may be utilized for the longer frequencies. A half wave dipole 50, center fed at the feed point 51, is supported by fixed supports 52 and insulators 53. A. front shunt element 54 is comprised of a coil 55 and. coupling portions 56 and supported by short lengths of wire 57 broken up by insulators 58. A rear shunt element 59 similarly includes a coil 6i and coupling portions 61. An insulating spreader 62 may conven- This shows that the shaded dipole of .4, iently be used to maintain the

coils

55 and 60 spaced from the dipole 5d.

The Figures 7 and 8 show a complete antenna array 65. The array 65 is mounted on a mast 66 which carries a horizontal boom 67. A second horizontal boom 68 is carried by the boom 67 and vertical booms 69 and 7d are carried by the ends of the boom 68. A shaded dipole 71 is symmetrically disposed on the boo-m 67. The shaded dipole 71 includes a tuned dipole 72 having a matching stub 73 and front and

rear shunt elements

74 and 75, respectively. The shaded dipole 71 is thus similar in configuration to the shaded dipole 31 of Figure 3 or a combination of Figures 1 and 2. Insulating blocks 76 are fastened to the boom 67 and adjustably clamp the

shunt elements

74 and 75 therebetween. This gives an adjustment on the spacing of the coupling portions at the ends of the shunt elements. The tuned dipole 72 is sandwiched between insulating blocks 77, and these are fastened to the boom 67. The front shunt element 74 is again found to be resonant to a higher frequency than the working frequency of the dipole 72, and the rear shunt element 75 is resonant to a lower frequency than the working frequency.

Collector elements

86 and 81 are disposed at the ends of the boom 68 and lie in a horizontal plane. The near ends 82 and 83 are disposed off the ends of the shaded dipole 71. The far ends of the collector elements and 81 lie forward of the shaded dipole 71. The collector elements 80 and 81 therefore are disposed generally linearly off the ends of the shaded dipole 71, and hence, may be considered as series elements relative to the tuned dipole 72 or shaded dipole 71. By superimposing the horizontal polar diagram of the shaded dipole shown in Figure 4 upon the top view of Figure 8 with a maximum forward lobe of the pattern of Figure 4 extending forward approximately 1.5 wave lengths, it will be noted that the collector elements 80 and 81 are generally parallel to the adjacent portion of the line denoting the field pattern. The fact that the shaded dipole has a cardioid field pattern with parts of the main lobe extending to the rear of the antenna location 88 on Figure 4 makes effective the use of the collectors 8t) and 81. The collectors 8t) and 81 are thereby disposed in the field of the shaded dipole 71 which would not be the case if only a straight dipole were being used with the typical figure 8 field pattern. Use of the collectors 80 and 81 increases the gain from the seven db of the shaded dipole up to approximately eleven db.

Additional collector elements

84, 85, 86, and 87 are carried on the

booms

69 and 70 above and below the plane of the

booms

67 and 68. The

collector elements

85 and 87 are above the horizontal plane of the

booms

68 and 67 with the near ends thereof disposed adjacent the ends of the tuned dipole 71. These collector elements slope downwardly toward the center as best seen in Figure 7. The

collector elements

84 and 86 are disposed below the boom 63 and slope upwardly so that the near ends thereof are disposed adjacent the tuned dipole 71.

Director elements

90, 91, and 92 of the Yagi type are disposed on the boom 67 in front of the shaded dipole 71. These director elements in the actual case tested were spaced forward of the tuned dipole 72 approximately one-third, .57 and .8 of a wave length, respectively. The director elements also tapered in length with the director element 92 being the shortest. The total db gain of the, entire antenna array 65 was found to be 16.5 db over a straight dipole.

The Figures 9 and 10 show the horizontal and vertical polarization patterns, respectively, of the antenna array 65 shown in Figures 7 and 8. These polarization patterns. show that the antenna array 65 has a narrow beam both horizontally and vertically with a front-to-back ratio of approximately twenty-three db. The Figure 11 is a plan view of another antenna array 95 with. all elements;

disposed in-a horizontal plane. The supporting structure for the various antenna elements is not shown, but it is understood that such may be similar to that shown in Figures 7 and 8. A shaded dipole 96 includes a tuned dipole 97 and front and rear shunt elements 98 and 99, respectively. A reflector element 100 of the Yagi type is spaced to the rear of the tuned dipole 97 in the order of one-quarter wave length. A director element 101 is spaced forward of the tuned dipole 97 in the order of two-thirds a wave length.

Collector elements

102 and 103 are disposed elf the ends of the tuned dipole 97 with these collector elements lying in the same horizontal plane but with the far ends spaced forwardly of the shaded dipole 96. These

collector elements

102 and 103 are similar to the collector elements 80 and 81 of the antenna array of Figures 7 and 8. The collector element 102 has a reflector element 104 and a director element 105 spaced rearwardly and forwardly thereof along a path generally parallel to the path formed by the shaded dipole 96 and the director 101. Similarly, the collector 103,has a reflector 106 and a director 107. Again the principal gain over the tuned dipole 97 is achieved by the front and rear shunt elements 98 and 99 which constitute the shaded dipole and the

collector elements

102 and 103. The

collector elements

102 and 103 are disposed serially off the ends of the shaded dipole 96 and are excited therefrom. Since the

collector elements

102 and 103 are excited, the

reflectors

104 and 106 and the

directors

105 and 107 will add to the forward gain just as the director 101 and reflector 100 on the shaded dipole 96 adds to the gain by being spacephased coupled thereto. The overall gain of the antenna array 95 has been measured to be approximately sixteen db over the tuned dipole 97.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred forin has been made only by Way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

'What is claimed is:

1. An antenna comprising a driven element having a resonant frequency and having two shunt elements coupled on opposite sides thereof and being resonant to higher and lower frequencies than said resonant frequency, and two elements disposed on opposite ends of the driven element and having resonant frequency characteristics.

2. An antenna comprising a driven element having resonant frequency characteristics, two shunt elements voltage coupled to said driven element on opposite sides thereof and being resonant to higher and lower frequencies than said resonant frequency, and two elements spaced on opposite ends of and generally linear with the driven element and having resonant frequency characteristics.

3. An antenna comprising a driven element and two shunt elements, said driven element being substantially resonant to a working frequency, said shunt elements being positioned closer than .05 wave length from said driven element for voltage coupling therewith and coupled on opposite sides thereof, said shunt elements being resonant to higher and lower frequencies than said working frequency, and two elements on opposite ends of said driven element and having resonant frequency characteristics.

4. An antenna comprising first and second elements, one of said elements having end portions spaced apart substantially equal to the electrical half-wave length thereof, the other of said elements having end portions spaced apart less than the electrical half-wave length thereof, the end portions of the second element being spaced from the first element and effecting a coupling therewith, said coupling comprising a voltage coupling which is greater than the radiated wave coupling, and feed line connections for one of said elements.

5. An antenna comprising first and second elongated elements, one of said elements having a length substantially equal to the electrical half-wave length thereof, the other of said elements having a length less than the electrical half-wave length thereof, means for electrically coupling the end portions of the first element to the second element, said coupling means comprising a voltage coupling which is greater than the radiation wave coupling, and feed line connections for one of said elements.

6. An antenna comprising first, second and third elongated elements, one of said elements having a length substantially equal to the electrical half-wave length thereof, the remaining elements having a length less than the electrical half-wave length thereof, means for electrically coupling the end portions of the first. and second elements to the third element, said coupling means comprising a voltage coupling which is greater than the radiation wave coupling, and feed line connections for one of said elements.

7. An antenna comprising first and second elements, said first element having a length substantially equal to the electrical half-wave length thereof, said first element having first and second coupling portions, the physical spacing between said first and second coupling portions being less than the physical length thereof, said second element having first and second coupling portions near the ends thereof and physically spaced apart less than the-electrical length of the second element, said first coupling portions of said first and second elements being adjacent and said second coupling portions of said first and second elements being adjacent and comprising a voltage coupling which is greater than the radiation wave v coupling therebetween.

8. An antenna comprising first and second elements, said first element having a length substantially equal to the electrical half-wave length thereof, said first element having first and second coupling portions, the physical spacing between said first and second coupling portions being less than the physical length thereof, said second element having a length varying from the electrical halfwave length thereof said second element having first and second coupling portions physically spaced apart less than the electrical half-wave length of the second element, said first coupling portions of said first and second elements comprising a capacitive voltage coupling, said second coupling portions of the first and second elements comprising a capacitive voltage coupling, and one of said elements being driven.

9. An antenna comprising first, second, and third ele ments, said first element having a length substantially equal to the electrical half-wave length thereof, said first element having first and second coupling portions, the physical spacing between said first and second coupling portions being less than the physical length thereof, said second and third elements each having first and second coupling portions near the ends thereof and having a physical length less than the electrical half-wave length thereof, said first coupling portions being adjacent and said second coupling portions being adjacent, each group i ments, said first element having a length substantially 1 equal to the electrical half-wave length thereof, said first element having first and second coupling portions, the physical spacing between said first and second coupling portions being less than the physical length thereof, said second and third elements each having first. and second coupling portions physically spaced apart less than the electrical half-wave length of the second and third elesee ers ments, respectively, said first coupling portions of said first and second elements and of said second and third elements comprising a'voltage coupling which is greater than the radiation wave coupling therebetween, said second coupling portions of the first and second elements and of said second and third elements comprising a voltage coupling which is greater than the radiation wave coupling thcrebetween, and one of said elements being driven.

11. An antenna comprising a dipole, an auxiliary element having first and second ends and being connected together by an intermediate conductive portion, said first and second ends of said auxiliary element spaced from said dipole and voltage coupled thereto at points thereon, the first and second ends of said auxiliary element being spaced apart with respect to each other such that the impedance of the auxiliary element is of the same order as the impedance between said points on said dipole.

12. A11 antenna comprising a dipole, feed lines connected to said dipole as a driven element, an auxiliary element having first and second ends and being connected together by a conductive intermediate portion, said first and second ends being spaced closer than said intermediate portion to said dipole, said first and second ends of said auxiliary element spaced from said dipole and volt age coupled thereto at points thereon, and the first and second ends of said auxiliary element being spaced fan ther apart with respect to each other than the spacing of each of said ends relative to said dipole.

13. An antenna comprising first and second main elements, each said first and second elements having inner and outer ends, said inner ends being more closely spaced than said outer ends, feed lines connected to the inner ends of said main elements, an auxiliary element having first and second ends connected together by an intermediate conductiye portion, said auxiliary elements first an second ends being spaced closer to said first and second main elements than the said intermediate portion is spaced to said main elements, said first and second ends of said auxiliary element spaced from said main elements and voltage coupled thereto at points thereon, and the first and second ends of said auxiliary element being spaced apart with respect to each other a greater distance than the spacing thereof relative to said main elements.

14. An antenna comprising a driven dipole, first and second elements each having outer ends and an interme diate portion, said first and second elements being bent so that the physical length thereof is less than the electrical half-wave length thereof, the ends of said elements being voltage coupled to said dipole, said dipole having generally a resonant length at a working frequency, said first and second elements being resonant to higher and lower frequencies than said working frequency, said driven dipole and said first and second elements being on generally opposite sides thereof in a given plane, and a director element resonant to a frequency higher than said working frequency spacephase coupled to said driven dipole and disposed in said given plane substantially parallel to said driven dipole.

15. An antenna comprising a driven dipole, first and second elements each having outer ends and an intermediate portion, said first and second elements being bent so that the physical length thereof is less than the electrical half-wave length thereof, the ends of said elements being voltage coupled to said dipole, said dipole having generally a resonant length at a working frequency, said first and second elements being resonant to higher and lower frequencies than said working frequency, said driven dipole and said first and second elements being on generally opposite sides thereof in a given plane, a director element resonant to a frequency higher than said working frequency space-phase coupled to said driven dipole and disposed in said given plane substantially parallel to said driven dipole, and first and second collector elements disposed substantially in said given plane each with first and second ends with the first ends adjacent the ends of said driven dipole, the second ends of each of said collector elements lying forward of said driven dipole, said collector elements lying generally parallel to the adjacent portion of the line denoting the field intensity pattern in said given plane of the combined driven dipole and first and second elements when such pattern has a line denoting the forward gain spaced ahead of said driven dipole approximately 1.5 wavelength, said collector elements being substantially resonant to said working frequency.

16. An antenna comprising a driven dipole, first and second elements each having outer ends and an intermediate portion, said first and second elements having a physical length less than the electrical half-wave length thereof, the end portions of said elements being voltage coupled to said dipole, said dipole having generally a resonant length at a working frequency, said first and second elements being resonant to higher and lower frequencies than said working frequency, said driven dipole and said first and second elements being on generally opposite sides thereof in a given plane, and first and second collector elements disposed susbtantially in said given plane each with first and second ends with the first ends adjacent the ends of said driven dipole, the second ends of each of said collector elements lying forward of said driven dipole, said collector elements being substantially resonant to said working frequency.

17. An antenna comprising a driven dipole, first and second elements each having outer ends and an intermediate portion, said first and second elements being bent so that the physical length thereof is less than the electrical half-wave length thereof, the ends of said elements being voltage coupled to said dipole, said dipole having generally a resonant length at a working frequency, said first and second elements being resonant to higher and lower frequencies than said working frequency, said driven dipole and said first and second elements being on generally opposite sides thereof in a given plane, first and second collector elements disposed substantially in said given plane each with first and second ends with the first ends adjacent the ends of said driven dipole, the second ends of each of said collector elements lying forward of said driven dipole, said collector elements being substantially resonant to said working frequency, a high frequency resonant director and a low frequency resonant reflector disposed forward and rearward of each of said collector elements in said given plane, said directors and reflectors being space-phase coupled to the respective collector elements.

18. An antenna comprising a driven dipole, first and second elements each having outer ends and an intermediate portion, said first and second elements being bent so that the physical length thereof is less than the electrical half-wave length thereof, the ends of said elements being voltage coupled to said dipole, said dipole having generally a resonant length at a working frequency, said first and second elements being resonant to higher and lower frequencies than said working frequency, said driven dipole and said first and second elements being on generally opposite sides thereof in a given plane, a director element resonant to a frequency higher than said working frequency space-phase coupled to said driven dipole and disposed in said given plane substantially parallel to said driven dipole, first and second collector elements disposed substantially in said given plane each with first and second ends with the first ends adjacent the ends of said driven dipole, the second ends of each of said collector elements lying forward of said driven dipole, said collector elements lying generally parallel to the adjacent portion of the line denoting the field intensity pattern in said given plane of the combined driven dipole and first and second elements when such pattern has a line denoting the forward gain spaced ahead of said driven dipole approximately 1.5 wave lengths, said colaseasrs lector elements being substantially resonant to said working frequency, and a high frequency resonant director and a low frequency resonant reflector disposed forward and rearward of each of said collector elements in said given plane, said directors and reflectors being spacephase coupled to the respective collector elements, each group of reflector, collector element and director lying in a path generally parallel to the front-to-rear path defined by said driven dipole and said director element.

19. An antenna comprising a driven dipole, first and second elements each having outer ends and an intermediate portion, said first and second elements being bent so that the physical length thereof is less than the electrical half-wave length thereof, the ends of said elements being voltage coupled to said dipole, said dipole having generally a resonant length at a working frequency, said first and second elements being resonant to higher and lower frequencies than said working frequency, said driven dipole and said first and second elements being on generally opposite sides thereof in a parallel to the adjacent portion of the line denoting the field intensity pattern in said given plane of the combined driven dipole and first and second elements when such pattern has a line denoting the forward gain spaced ahead of said driven dipole approximately 1.5 Wave lengths, said collector elements being substantially resonant to said working frequency, and additional collector elements substantially resonant to said working fre queney and each having a near end and a far end with said near ends disposed adjacent the ends of said driven dipole and lying spaced from and at an acute angle to said given plane and lying in planes passing through said first and second collector elements with said last mentioned planes substantially perpendicular to said given plane.

20. In combination, a dipole, and an elongated element resonant to a frequency lower than that of said dipole and voltage coupled near its ends to said dipole.

21. In combination, a dipole, and an elongated element resonant to a frequency higher than that of said dipole and voltage coupled near its ends to said dipole.

22. An antenna comprising, a driven element having a resonant frequency, and a shunt element voltage coupled on one side thereof and having resonant frequency characteristics different from that of said driven element.

23. An antenna comprising, a driven element having a resonant frequency, a shunt element voltage coupled on one side thereof and having resonant frequency characteristics different from that of said driven element, and two elements generally linearly disposed on opposite ends of the driven element and having substantially resonant frequency characteristics.

24. An antenna comprising, a driven element and two shunt elements, said driven element being substantially resonant to a working frequency, said shunt elements being positioned closer than .05 wave length from said driven element for voltage coupling therewith and coupled on opposite sides thereof, and said shunt elements having resonant frequency characteristics higher and lower than said working frequency.

25. An antenna comprising, first and second elements, one of said elements having end portions spaced apart more than the electrical half-wave length thereof, the other of said elements having end portions spaced apart less than the electrical half-wave length thereof, and means eifecting a voltage coupling with said end portions which is greater than the radiated wave coupling.

26. An antenna comprising, first and second elements, one of said elements having end portions spaced apart more than the electrical half-wave length thereof, the other of said elements having end portions spaced apart less than the electrical half-wave length thereof, and dipole means having portions efiecting a voltage coupling with said end portions which is greater than the radiated wave coupling.

27. An antenna comprising, first and second elongated elements, one of said elements having a length substantially equal to the electrical half-wave length thereof, the other of said elements having a length less than the electrical half-wave length thereof, and means for voltage coupling the end portions of the first element to the second element.

28. An antenna comprising, first and second elongated elements, one of said elements having a length substantially equal to the electrical half-wave length thereof, the other of said elements having a length greater than the electrical half-wave length thereof, and means for voltage coupling the end portions of the first element to the second element.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,273 Kearse Sept. 26, 1950 2,505,115 Hills et al. Apr. 25, 1950 2,572,166 Lorusso Oct. 23, 1951 2,578,973 Hills Dec. 18, 1951 2,580,798 Kolster Jan. 1, 1952 2,640,933 Spindler June 2, 1953 2,789,286 Marshall Apr. 16, 1957 FOREIGN PATENTS 146,302 Germany July 14, 1901