US2671852A - Resonant antenna - Google Patents

Description

March 9, 1954 J. J. BUBBERS ETAL RESONANT ANTENNA lo MLENQRS BY MM2/fa /Jdwam ATTORNEY Filed Dec. 5 1951 Patented Mar. 9, 1954 UNITED kSTATES PATENT oFiFic'E :RESONANT ANTENNA .Application December 5, 1951,.'Se1'ial.No.3259;966

.9 Claims.

This invention relates to a high frequency ane tenna .which may be used for television .and other high frequency systems.

The antenna of the instant invention is designed to operate at a resonant frequency so that it is not of the wide-band type as is generally used for television purposes where a considerable number of stations are to be served by a single antenna. On the other hand, the antenna exhibits the high gain and low noise characteristics of narrow band elements.

The antenna of the instant invention is a broadside array constructed according to the principles of quarter wave elements rather than the conventional half wave elements. These elements are arranged physically so that the antenna requires a minimum of space, a characteristic which is important in View of current tele vision antenna installation problems. At the same time, the instant antenna provides simpliied mounting and installation means in that insulators are substantially dispensed with. No insulators are required .between a radiator and a reector of the instant invention, and none is required between a supporting mast and the complete antenna structure.

Additional desirable characteristics of the antenna will be understood from the following description and drawings in which:

Figure l is an elevational view of the basic form of the instant antenna;

Figure 2 is a perspective view of the antenna which includes a reflector; and

Figure 3 is an elevational view of a stacked form of antenna employing the principles of the instant invention.

The basic form o1" the antenna vis shown in Figure l illustrating it as frame-shaped in the form of a rectangle. Lead in transmission wires are connected to terminals It and il of the arms I2 and i3 respectively. Arms I2 and I3 are eighth wave elements in respect to the resonant .frequency of the antenna which, for example, may be that of any station in the television band. Accordingly, arms I2 and I3 together constitute a transverse, centrally gapped or split quarter wave central element, terminals Id and II being connected to its inner ends. Arms I4, I and IS are each a quarter of a wave length long as are the lower arms I1, I3 and I9. Aligned arms it and Il comprise one of the long sides of the rectangle, aligned arms I5 and I9 comprising the other vlong side. Arms I5 and It are the short sides.

The above arrangement is such as to employ the electrical characteristics of quarter wave ele- (Cl. Z-33.51.)

ments in that they `serveas phase .reversal members at the resonant frequency. .By virtueof the arrangement disclosed, vra'di'atien'occurs .from fthe horizontal elements 42, 13, I5 and I8 while radiation from the arms I4, I6, IFI .and :I9 ris absent because of opposing current flows. Thus, assuming that the antenna is excited V.at the terminal points Ii) vand II as illustrated, point 20 will be negative while point 2l will -be positive, a quarter wave length `occurring between these two points. At points 2:2 and l231phase reversal takes place so vthat points .'24 and 25 farenegative. Similarly, points .26 and 2-`I are positive. AIt will be evident therefore, that .the currents in arm I5 are .in vphase and their nelds `are additive in the plane Lperpendicular to the figure. The .same condition exists for arms I.2 and lf3 and varim \I B. On the other hand, inasmuch as phase reversal occurs at point 22 of .arm I4 so as -to produce current cancellation, .no radiation takes place from that arm as indicated by the arrows. The same condition of current cancellation exists .for arms :16, fI'I and I9.

It will .be seen from the foregoing that radiation ycan `take place only .in one fplane from the horizontal :arms and no radiation takes place from the vertical arms. As `above set forth, this results from the use of :quarter Wave :elements and lemploying the phase .reversal characteristics thereof to produce :current .cancellation where not ydesired and addition in the .plane desired.

Theantenna as above described Vpermits .a simplifed form of reiector 4to be 'added thereto. The reflector .-30 is shown in Figure 2 and substantialhr duplicates the basic form although .it 4may be approximately 3 percent larger as is conventional. Cross beams -3I and 32 are approximately 0.2 wave length long, the customary 4length for such cross beams. It Will be noted that points A32's, 34, 35 and .3S comprise voltagenodes so that no rinsulation at the ends of the cross beams .is necessary. Hence, any type of fastening may be employed at these points. .By the same token, a mast 37| may be connected to cross arms 3l and `32 without requiring insulation. Accordingly, the manufacture and installation of the .antenna effects considerable economies.

The simplicity of the above described antenna should be evident. Notwithstanding such simplicity, its gain is unusually high. Measurements have been indicated that the Astanding wave ratio with standard 300 ohm line was extremely low at the resonant :frequency While pronounced ygain was manifested relative to a resonant dipole. The beam width in the horizontal plane was found to be about 58 at the half power point with only a small minor lobe appearing at the backside of the beam and with substantally no other minor lobes in the horizontal plane.

In Figure 3 is illustrated a stacked form of the antenna. It is only necessary to add successive frames having the same dimensions as above described. The action of the horizontal and vertical elements will follow the principles above set forth. As in the previous embodiment, a reector is employed to make the system uni-directional. The stacked form of antenna, having nve horizontal elements as indicated in Figure 3, exhibits a marked gain over the basic construction. It is found that the horizontal pattern still has no minor lobes excepting one in back of the antenna which is characteristic of parasitic arrangements and is of no importance for most applications.

The above description assumes the use of the antenna for horizontally polarized waves. However, the same principles would apply to vertically polarized waves it being only necessary to rotate the structure 90 from that shown in the drawings, and it is therefore understood that the invention is directed to both types of polarization.

What is claimed is:

l. A resonant antenna comprising a quarter wave input arm, said input arm having two spaced inner ends for receiving a pair of lead in wires, a first pair of quarter wave arms extending perpendicularly in one direction from the respective outer ends of said input arm, a second pair of quarter wave arms extending outwardly perpendicularly in the opposite direction from the respective outer ends of said input arm, two additional quarter wave arms respectively connecting the outer ends of said first pair of arms and said second pair of arms, and a supporting mast connected to one of said two additional quarter wave arms, said inast connection being free of insulation.

2. An antenna resonant at a predetermined frequency, said antenna being a frame-shaped structure and comprising two long sides and two short sides forming a rectangle, said long sides each consisting of two aligned quarter wave arms at said frequency and said short sides each consisting of one quarter wave arm at said frequency, a central, transverse quarter wave arm extending parallel to said short sides and having its ends connected to the respective centers of said long sides, means to connect a pair of transmission wires to said central arm, and a supporting mast connected to one of said short sides and being free of insulation therefrom.

3. An antenna resonant at a predetermined frequency, said antenna comprising a radiator and a reector spaced therefrom, said radiator being a frame-shaped structure and comprising two long sides and two short sides forming a rectangle, said long sides each consisting of two aligned quarter wave arms at said frequency and said short sides each consisting of one quarter wave arm at said frequency, a central, Vtransverse quarter Wave arm extending parallel to said short sides and having its ends connected to the respective centers of said long sides, said central arm having a central gap adopted to receive a pair of input transmission wires, said reector substantially duplicating the structure of said radiator, the central arm of said reflector being continuous, and a pair of cross beams each extending from the center of one of the-radiator short sides to the center of one of the reflector short sides.

4. An antenna according to claim 3 and wherein all of the connections of the arms to each other and to said cross beams are direct and free of electrical insulating material.

5. An antenna resonant at a predetermined frequency, said antenna being a frame-shaped structure and comprising two long sides and two short sides forming a rectangle, said long sides each consisting of two aligned quarter wave arms at said frequency and said short sides each consisting of one quarter wave arm at said frequency, a central, transverse quarter wave arm extending parallel to said short sides and having its ends connected to the respective centers of said long sides, said central arm having a central gap adopted to receive a pair of transmission wires, and additional quarter wave arms extending in further alignment with each of said long sides and additional transverse arms connecting the ends of said additional quarter wave arms and extending parallel to said short sides.

6. An antenna according to claim 5 and wherein said additional quarter wave arms extend from both of said short sides.

7. An antenna according to claim 6 and wherein the structure recited comprises a radiator, said antenna further including a reflector spaced from said radiator, said reflector having substantially the same shape as said radiator, a series of cross beams extending from said radiator to said reflector at connection points disposed at the centers of at least two of said cross beams, said connecting points being free of insulation.

8. An antenna resonant at a predetermined frequency, said antenna being a frame-shaped structure and comprising two long sides and two short sides forming a rectangle, said long sides each consisting of two aligned quarter wave arms at said frequency and said short sides each consisting of one quarter wave arm at said frequency, a central, transverse quarter wave arm extending parallel to said short sides and having its ends connected to the respective centers of said long sides, and said central arm having a central gap adopted to receive a pair of transmission wires, said structure constituting the radiator of a unidirectional antenna and further comprising a reflector spaced from and substantially duplicating the said frame-shaped structure, said reflector having its central transverse arm continuous from one long side to the other, and at least one cross beam connecting said radiator and reflector, said cross beam extending from the center of one of said short sides of the radiator to the center of one of the short sides of the reector.

9. An antenna according to claim 8 and wherein all the connections of the arms to each other and to said cross beam are free of insulation.

JOHN J. BUBBERS. ROBERT E. STUHLER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,966,491 Ferrell July 17, 1934 2,082,812 Worrall June 8, 1937 2,156,661 Wells May 2, 1939 2,163,770 Von Radinger June 27, 1939 2,283,897 Alford May 26, 1942

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