US2112269A

US2112269A - Directional antenna

Info

Publication number: US2112269A
Application number: US110599A
Authority: US
Inventors: Philip S Carter
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1936-11-13
Filing date: 1936-11-13
Publication date: 1938-03-29
Anticipated expiration: 1955-03-29

Description

March 29, 1938. P. s. CARTER DIRECTIONAL ANTENNA Filed NOV. 13, 1956 tm v III"

INVENTOR PHILIP 5. CARTER BY v ,um

ATTORNEY Patented Mar. 29, 1938 PATENT OFFICE DIRECTIONAL ANTENNA n Philip S. C'arter, Port Jeierson, N. Y., assigner to Radio Corporation of America, a. corpora tion of Delaware Application November 13, 1936, Serial No. 110,599 9 claims. (C1. 25o-11) This invention relates to-a directional antenna system, and more particularly to such a system wherein there are employed a plurality of individual radiating elements so arranged that the currents therein bear a desired phase relation with respect to one another.

In the transmission of horizontally polarized Waves, it has heretofore been proposed to employ a plurality of half wavelength, approximately horizontal radiating elements arranged in substantially the same straight line and disposed vertically approximately one-half wavelength from a similarly arranged group of half wavelength radiating elements, and so energized that the direction of lradiation is perpendicular to the axis of the radiating elements. In such known arrangements, the approximately one-half wavelength vertical spacing between the two groups of radiators was necessary in order toprovide desired cophasal relationship of the currents in all the radiating elements. A disadvantage of this type of antenna is the fact that there is required, for its proper mechanical construction, a catenary arrangement which enables the individual radiating elements of each group or tier to be aligned in the same straight line, at a constant vertical spacing between adjacent tiers. Another disadvantage lies in the absence of any provision for adjusting the phase relation of the currents in the wires. In practice, some adjustment is always necessary to obtain ythe desired directional effect, since it is difficult, if not almost impossible, to determine the effects upon the phase relations of the currents, of such iactorsasinsulators, and the looping and bending of the feeder wires'between adjacent radiating elements of the same group. A further disadvantage of the known antenna systemfdescribed above lies in the necessity of providing an approximately one-half wavelength vertical spacing between groups of one-half Wavelength radiating elements lying substantially along dierent axes.

The foregoing disadvantages arer overcome in accordance with the present invention which provides a highly directional antenna of the type described above, but which is not limited toany one particularv value of spacing betweenadjacent groups of radiators, and which provides for proper adjustment of the phase relations between currents in the radiators of each group. A detailed description of the invention, accom.- panied by-a drawing follows:

Referring to the single figure of the drawing, there is shown falbroadside antenna system vfor radiating horizontally polarized waves, comprising two groups of substantially half wavelength radiating elements I, I and 2, 2 suitably supported between poles P, P. Each radiating element I and 2 is electrically'separated from its adjacent element, extending generally along the same axis, by an insulator herein designated X, although adjacent radiating elements are electrically coupled together through vertical interconnecting wires 3, 4, which extend between groups I, I and 2, 2.

For energizing the antenna system, there is provided a suitable transmitting circuit, herein conventionally shown in box form 5, which is connected over transmission line TL and through a suitable impedance matching circuit 6 to the center points of the middle pair of vertical interconnecting wires 3', 4. The connection of the transmission line TL to the center points of the middle wires 3, 4 insures the cophasal excitation of the rlrst two radiators in each group to which the vertical wires are directly connected. For achieving cophasal excitation in adjacent radiating elements 2, 2 and I, I of each group of radiators, there are provided across the interconnecting wires 3, 4 a pair of conducting strips 1 and 8 which can be adjusted over the lengths of the wires 3, 4. Strips l and 8 are symmetrically located With respect to the centers of the interconnecting wires 3, 4. In this manner, by suitable adjustment of the strips, there is obtained cophasal energization in the radiating elements, and out of phase energization in `those portions of the wires 3, 4 which extend from the stripI to their associated radiators. When `the wires are perfectly tuned, the strips 'I and 8 will be located at a voltage nodal point for the energy in the wires. The current distribution throughout the radiating elements of the interconnecting wires are shown by dotted lines, and the" arrows indicate the direction of the instantaneous current How in the radiators and wires. It will thus be observed that there is substantially complete cancellation of radiation from' the interconnecting wires 3, 4, although addition of radiation from the radiating elements I, I and Due to the fact that the voltages on the strips 'I and 8 are a minimum and equal in value, it is4 possible to connect the conducting strips together through the intermediate portions' of `the interconnecting wires 3, 4 without the use of` insulators, thus achieving another advantage over prior arrangements wherein additional insulators` are necessary at the equivalent ofthis location to prevent direct contact between adjacent crossconnecting feeder wires.

Because of the fact that the strips 'I and 8 are adjustable over the lengths of the Wires 3, 4, it is possible to overcome various irregularities in the system and thus obtain the desired currents and phase relations in the radiators. Also, by adjusting strips 'I and 8, the antenna can be made to accommodate a considerable range of frequencies, in which case the radiating elements I, I and 2, 2 may depart from an exact ha wavelength.. l

It should be noted that although the radiator of each group I, I and 2, 2 are substantially, more or less so, in the same line, there is a departure from this straight line due to mechanical considerations. For this reason the spacing between the two groups of radiators I, I and 2, 2 is not constant, and varies from maximum spacing at the points of suspension at the poles'P',

to a `minimum spacing at the center of the span between the poles. In this way the wires themselves form a sort of catenary, whereas` heretofore, in priorV arrangements, it has always been necessary to provide a separate catenary from which the antenna elements were suspended.

`It will thus be obvious, from an inspection of the drawing and what has been said before, that the minimum spacing between groups ofradiators I, I and 2, 2 should not be substantially less than one-half wavelength, since it is desired that the overall length of path from the adjacent ends of any two radiators in the same group, as measured along wires 3 and 4 and through its associated strip, be in electrical effect, equivalent to one-half Wavelength, in order that the phase relations be the same in the adjacent radiating elements. It is preferred, however, that the mean or average spacing between the groups f ,i of radiators I, I and 2, 2 be greater than onehalf wavelength for two purposes. First, in order to give the strips l and 8 a degree of adjustability overthe wires 3, 4, for accommodating a range of frequencies, and secondly, because I have found that the mean spacing which will give the maximum power `gain for the arrangement shown in the drawing of the two groups of radiators is about 'lths .of a wavelength. Such a spacing will, theoretically, give'a power gain of three to one over a single group of elements, whereas a half wavelength spacing between groups of radiators will give a power gain of only slightly more than two to one, as compared to a single group of radiating elements.

Although the antenna of the invention has been described especially in regard to a transmitter, it willbe understood, of course, that it is not limited thereto but it may be applied as well to receiving arrangements, and that, if desired, reflectors maybe employed at suitable distances in the rear of the antenna. Such reflectors may have the identical form of the antenna of the invention, or be of any other desired configuration. Similarly, the reflector may be directly energized'or parasitically excited (floating). It should also be understood that the invention is not limited to any particular number of elements in any one group, since a greater or less number than that shownk might be employed between any two poles. Moreover, the features of the invention are not limited to a horizontal antenna. for the transmission of horizontally polarized waves since, where desired, a vertical antenna employing the invention may also be used, in which case the radiatingelements I;

I and 2, 2, and the strips I and 8 would be vertically disposed while the interconnecting wires 3, 4 and 3', 4 would be horizontally disposed. Occasions may also arise where it is desired to use a polarization which is not strictly vertical or horizontal but is at some desired angle, in which case the antenna of the invention may be disposed at any angle to the horizontal or vertical, without departing from the spirit and scope of the appended claims.

What is claimed is:

l. An antenna system comprising two radiating elements,` each substantially one-half the length of the communication wave and disposed in substantially the same straight line, two other similar radiating elements disposed substantially in a line parallel tosaid first two elements, a pair of interconnecting Wires disposed substantially at a right angle to said first two pair of radiating elements and connecting the adjacent ends of said first two radiating elements to the adjacent ends of said second two radiating'elements, and means connected across and adjustable along the lengths of said pair of interconnecting wires for adjusting thecurrent and phase relations in said radiating elements.

2. An antenna in accordance with claim l, characterized in this that said means comprise two electrical conductors substantially symmetrically disposed with respect to the center of said interconnecting wires.

3. An antenna comprising a plurality of linear radiating elements in the form of a line supported at both ends from a pair of vertical supporting structures, another group of radiating elements similarly arranged and supported between said structures and spaced away from said first group, an insulator between adjacent radiating elements of each group, a pair of interconnecting wires connecting the adjacent ends of the radiating elements in one group with the correspond-` ingly located adjacent ends of the radiating elements of the other group, and a pair of conducting strips connected across and adjustable along the lengths of each pair of interconnecting wires for adjusting the current and phase in said radiating elements.

,v 4. An antenna in accordance with claim 3, characterized in this that the two groups of radiating elements are substantially horizontal and in the form of catenaries, the average spacing between said two lines of Yelements being greater than one-half the length of the communication wave. v

5. AnA antennaA comprising a plurality of linear radiating elements in the form of a line supported at both ends from a pair of vertical supporting structures, another group of radiating elements similarlyarranged and supported between said structures and spaced away from said rst group, an insulator between adjacent radiating elements of eachv group, a pair of interconnecting wires connecting the adjacent ends of the radiating elements in one group with the correspondingly located adjacent ends of the radiating. elementsv of theother group, and a pair of conducting'strips connected across each pair of interconnecting wires for adjusting the current and phase ini said radiating elements, said two lines. offradiatingv elements being substantially horizontal and in the form of catenaries, the average spacing between said two lines being substantially seven-tenths ofthe length of the communication wave.

6. An antenna comprising a4 plurality of linear arrangement located between each of said iirstl radiating elements in the form of a line supported at both ends from a pair of vertical supporting structures, another group of radiating elements similarly arranged and supported between said structures and spaced away from said rst group, an insulator between adjacent radiating elements of each group, a pair of interconnecting wires connecting the adjacent ends of the radiating elements in one group with the correspondingly located adjacent ends of the radiating elements of the other group, and a pair of conducting strips connected across each pair of interconnecting wires for adjusting the current and phase in said radiating elements, said two lines of radiating elements being substantially horizontal and in the form of catenaries, the average spacing between said two lines being' greater than one-half the length of the communication wave, said catenaries having opposite curvatures.

7. An antenna system comprising two radiating elements, each substantially one-half the length of the communication wave and disposed in substantially the same straight line, two other similar radiating elements disposed substantially in a line parallel to said iirst two elements, a pair of interconnecting wires disposed substantially at a right angle to said first two pair of radiating elements and connecting the adjacent ends of said rst two radiating elements to the adjacent ends of said second two radiating elements', means connected across said pair of interconnecting wires for adjusting the current and phase relations in said radiating elements, another similar arrangement of four radiating elements similarly coupled together and arranged in substantially the same plane as said first four radiating elements, each line of radiating elements in said iirst arrangement having a substantial continuation of said line in said second arrangement, a supporting structure between said two arrangements of radiating elements, another pair of interconnecting wires disposed substantially at a right angle to said two lines of radiating elements and connecting' together the ends of the elements of each arrangement nearest said supporting structure, and high frequency apparatus coupled to the center points of said last pair of interconnecting wires.

8. An antenna system comprising rst, second and third successively spaced supporting structures, said rst and third structures being equally spaced from said second structure, an antenna and third structures and said second structure, said antenna arrangements being in the same plane, similarly constructed, and supported at the same height above ground from said structures, each of said antenna arrangements comprising two groups of substantially horizontal radiating elements in the form of catenaries, said catenaries of each antenna being separated from each other an average vertical distance greater than one-half the length of the communication wave, each of said radiating elements being approximately one-half the length of the communication wave, and pairs of interconnecting wires disposed at substantially right angles to said elements and connecting the adjacent ends of the elements of one group to the adjacent ends of the correspondingly located elements of the other group in the same antenna arrangement, conducting strips connected across each pair of interconnecting wires for adjustingv the current and phase relations in their directly associated radiating elements, whereby each element in each group is coupled to the adjacent element of the same group through said interconnecting wires and a strip, and high frequency apparatus coupled to the radiating elements of both said antenna arrangements which are nearest said second supporting structure.

9. An antenna comprising a plurality of linear radiating elements in the form of a line supported at both ends from a pair of vertical supporting structures, another group of radiating elements similarly arranged and supported between said structures and spaced away from said rst group, an insulator between adjacent radiating elements of each group, a pair of interconnecting wires connecting the adjacent ends of the radiating elements in one group with the correspondingly located adjacent ends of the radiating elements" PHILIP S. CARTER.