US2447768A - Microwave antenna - Google Patents

Description

Aug. 24; 1948. G. E. MUELLER MICROWAVE ANTENNA 2 Sheets-Sheet 1 Filed July 22, 1942 FIG. 2

muses/van INVENTOR G. E. MUELLER ATTORNEY Patented Aug. 24, 1948 George E, Mueller, Jackson Heights, N. Yvessignor t-o Bell Telephone ,Laboratories, Incorporated, New York York, N. Y.,sa 'corporation'of New Application July 22;, 1942,Serlal No. 451,864

"This invention relates todirective antenna systems and particularly to directive microwave antenna systems. i

:As disclosed in Patent .2;4-1'1,872 granted onDecember 3, 1-946, to'C, :B. Feldman and E. Mueller, high-lydirective radio action and ;a large gain .may he obtained by utilizing a plurality of microwave open-ended wave guides in :an end-on organ pipe array. In this arrangement, the widths and lengthsof the pipes or guides are selected-so that the wavelets emitted in the end-on direction are in phase :agreement, substantially. As stated in-ithe above-mentioned application, it has been found in pr-acticetthat, while thedirection oi maximum action in the magnetic plane is aligned with the longitudinal axis of the organ pipe antenna, the direction of maximum. action in the plane of polarization, that is, the electric plane, is not exactly aligned with the aforementioned axis because of mutual coupling between the apertures or elemental antenna and because of other effects. It now appears desirablaexactly to align, in end-on antenna systems of thehigh gain :organ pipe type, the electric. plane direction of maximum action, as well as the magnetic plane direction of action, with the longitud-inal axis of the system. More particularly, it appears advantageous in radio scanning systems, to have theprincipal radius or axis of the maximumdirective lobe, considered .in the solid, rather than .a .minor axis of the aforementioned lobe, aligned with the longitudinalaxis-of the system or array inorder to facilitate the direction determination,

It is .one object of this invention'to obtain a microwave array having an exceedingly high gain.

It is another object of this invention to obtain ,a microwave antenna having a highly directive characteristic. I

It is still another object of this invention to collect or project, from both sides or legs of a microwave V antenna, wavelets having the same polarity.

It is an additional object of this invention "to "align, in a microwave antenna array having a high gain, the magnetic plane and'electric plane directions of maximum action.

It is a further object of the invention to compensate for aperture :coupling effects in an -organ pipe waveguide array.

In accordance with the preferred embodiment of the "invention, a transceiver of "the type employed in conventional radars, range finding radio scanning systems, isconnected by :a main wave guide to a wave guide antenna array com- ,prising two Eo'rgan pipe arrays of -.the,ty;pe disclosed 1060mm. (o1. cam-sacs) L2 in the above-mentioned copending application. The stepped b sides containing the spaced elemental antenna apertures face each other, and 'thel-ongitudinal axes tor the two organpipe arrays, hereinafter called subarrays, extend paralleLm-at a slight angle, to "the desired direction of maximum action. The individual directions of maximumaction'in the electric plane for the :two subarrays are aligned with the longitudinal axis "of the array, or are anguiarly related thereto, so that thedirection of maximumaction in this plane tor the entire array coincides with the bisector of the angle formed "by the apertured'or stepped sides. Since the magnetic -plane direction of :action for ea-chsu'b arraycoincides wi ththe longitudinal su'barray :axis aslnth'e structure of the oo-pending application, the electric and magnetic plane -direetionsof maximum action-coincide. Stated difterently, the direction of maximum action, considered in the solid, for the systemds along a singlezpa'thwhich is aligned with the longitudinal axis of the array.

. The "invention will he more fully understood *fromaaperusalof the following specification taken in -connection withthe draw-ing-onwhich like reterence characters denote elements of similar function, and on which:

Fig. 1 illustrates :a perspective view of one embodimentnf the invention comprising a--U--shaped broadside array of two end-on organ pipe subarrays Fig. 2'rillustrates a perspective view of the preferred embodiment of the invention comprising a V-shaped broadside array of two organ pipe subarrays; and

Figs. -3 and 4 are curves illustrating the directional characteristics or the preferred embodimentzofFigl.

, Reierring toiFig. 1, reierencenumerall denotes a translation device such :as a :pulse transceiver commonly used in radio scanning systems and numeral -2 designates a coaxial line comprising an ,inner conductor 3 and an outer conductor 4. and coupled to the mid-point 5 of a curved .rectangu-l'ariwaveguide-6. Numerals land 8 denote .organ pipe subarrays of the type disclosed in the aforementioned patent. Each subarray-comprises a plurality 'of open-endecl air-filled rectangular wave guides 9 having end apertures or elemental antennas Ni and ,graded lengths. The guides or pipes 9 have, in general, different b or wide transverse dimensions, -and therefore different phase velocities, so that in operation, as explained in .theatoresaid Patent 2,411,872, the waves supipliedtothe addacent'openlinput ends H of pipes both subarrays are vertically polarized as shown by arrow l4. Preferably, the axes l2 and I3. ex-

tend parallel to the array axis [5.

In operation, waves are supplied by'device '1 over line 2 to the mid-point of guide-'6, through the two equal length sections I6"of guide 6 to the input openings ll of pipes 9 in sub-arrays 1 and 8, and are radiated from elemental antennaapertures l0. As previousl explained, the radiated wavelets combine cophasally in the general propagation directions l3 and I5. More accurately, considering subarray 1, the wavelets add to produce, in the plane of polarization, hereinafter called the electric plane (XY plane, Fig, 1), a direction of maximum action angularly related to axis l2, as represented by the single- 4 with, or parallel to, the array axis l5, as in the system of Fig. 1. The double-headed arrow 32 represents the direction of the maximum action in the magnetic plane for the entire array. In Fig. 3, the curve 33 illustrates the directive lobe in the magnetic plane for each of subarrays andi8 and curve 34 illustrates the combined or resultant array'lobe. In the electric plane, as suming the axes I2 and I 3 are parallel and in a vertical plane, the direction of maximum action for subarray l is downward and toward the axis l4 and for subarray 8 it is upward and toward axis M, as shown inFig. 2 by arrows 35 and 36,

respectively; The resultant lobe has its principal axis aligned with the direction represented by the single-headed arrow 37. In Fig. 4, curves 38 and '39 denote the lobes, in the electric plane, respectively, for subarrays and 8, and

' curve lo illustrates the combined or resultant headed arrow 17. In the horizontal or magnetic plane (XZ plane, Fig. 1) the wavelets combine in a manner such that the maximum action for the subarray is in a direction aligned with the longitudinal axis I2, as shown by the doubleheaded arrow I8. Similarly, considering subarray8, the electric plane direction I!) and the magnetic plane direction of maximum action are angularly related and aligned, respectively,

with the axis l3. For the entire array, the two electric plane directions" and IQ of maximum action coincide, as illustrated by the singleheaded arrow 2|, and the two magnetic plane directions l8 and 20 likewise coincide, as indicated by double-headed arrow 22. As a result, the array has a considerably greater gain than the single pipe organ array disclosed in the aforesaid Patent 2,411,872 and a greater gain for a given area perpendicular to the direction of radiation than realized with the so'-called panel antennas, for example, a parabolic reflector system, commonly used in the microwave field. If desired, the electric plane directions I! and I9 may be aligned, respectively, with directions l8 and 20, by tilting the entire array.

Referring to Fig. 2 the subarrays 1 and 8 have their stepped or apertured sides 23 and 24 facing each other, the longitudinal axes l2 and 13 being parallel or angularly related as explained below. Numerals 25 and 26 denote two guides of equal length which are connected through the main guide 2'! to the coaxial line 2 and device I. The coaxial line 2 is connected to guide 21 at a distance a quarter wave-length from the closed guide end 28, theclosed end being a reflector similar to the antenna reflector employed in conventional short wave unidirectional systems. As in the structure of Fig. 1, the portion of the inner conductor 3 extending into the associated guide is parallel to the narrow transverse or electric plane guide wall, so that the wave components supplied to the pipes in subarrays 1 and 8 are polarized verticall as indicated by arrow 29.

In operation, referring to Figs. 2, 3 and 4, the wavelets supplied by device I to subarrays 1 and 8 are radiated from the apertures l0, and considering the magnetic plane, the phases of the wavelets are such as to produce maximum action in the directions 30 and 3| coinciding lobe. Preferably, the angle 4|, Fig. 2, between the apertured surfaces 23 and 24 is initially chosen or adjusted, so that electric plane directions and 36, Fig. 2, coincide respectively with magnetic plane directions 30 and 3 I, whereby the radio action in the electric plane direction 3'! is enhanced, and maximum gain, in the direction 37 of maximum action, is obtained as illustrated by arrow 42. In other words, preferably, angle 4| is such that lobes 38 and 39, Fig. '4, are superimposed and symmetrically disposed relative to axis l5 as illustrated by curve 43 of Fig. 4 and instead of the blunt relatively short lobe 40, the highly desirable sharp and relatively long lobe 44 is obtained. As in the system of Fig. 1, the gain over a standard antenna is considerably greater than that achieved by a single organ pipe antenna or a panel type antenna. Thus, in accordance with the invention, a microwave array having an exceedingly high gain andelectric and magnetic plane directions of maximum action aligned with the array axis is obtained.

Although the invention has been explained in connection with certain embodiments, it should be understood that it is not to be limited to the embodiments described inasmuch as other apparatus may be successively employed in practicing the invention.

What is claimed is:

1. A microwave antenna comprising a plurality of subarrays each comprising a pluraltiy of parallel wave guides having different lengths and end-antenna apertures.

2. A microwave V antenna comprising two subarrays each comprising at least two parallel wave guides of difierent length and having end apertures, the corresponding apertures of said subarrays being equally paced in the desired endon direction of maximum action.

3. A microwave V antenna array comprising two organ pipe subarrays having their apertured sides facing each other, the angle between said sides being a function of the spacing and mutual coupling between the adjacent apertures in each subarray.

4. A broadside microwave antenna array of parallel end-on sub-arrays, said subarrays having superimposed directions of maximum action in a. plane including the axes of the subarrays, and angularly related directions of action in a plane perpendicular to said plane and including said axes, the bisec'tor of the angle formed by said angularly related directions being aligned with said axes, whereby the directions of maximum action in said plane for the broadside array are superimposed.

5. A microwave V antenna comprising two sets of open-ended parallel wave guides connected to a translation device, the adjacent guides in each set having a given diiference in length, the end openings of the two longer guides being farther apart than the openings of the two shorter guides.

6. A microwave antenna array comprising two subarrays of parallel open-ended wave guides, the guides in each subarray having wide transverse dimensions of different widths and a difference in length dependent upon the difference inwidth, means for supplying similarly polarized wavelets to all of said guides, the direction of maximum action in the plane of wave polarization of each subarray being at an angle to the longitudinal axis of the subarray, and the said direction being in effect superimposed.

7. A V antenna comprising two organ pipe subarrays each comprising a plurality of parallel wave guides having graded lengths, one set of corresponding ends of said guides being connected through dielectric paths of equal lengths to a translation device, and the other set .of corresponding ends having apertures included in the same wave front plane.

8. A microwave antenna array comprising tw subarrays each comprising a plurality of openended wave guides of different length, the electric plane directions of maximum action of said subarrays making equal angles with the desired endon direction of action coinciding with th 1 mm. dinal axis of said subarrays.

9. A microwave V antenna array comprising two subarrays each comprising two parallel wave guides of different lengths, the guides in each subarray having one set of corresponding end adjacent and connected to a .translation device and apertures at their other ends, the apertures of one subarray being spaced along one side and the apertures of the other subarray being spaced along the other side of an angle having its bisector aligned with the desired direction of action, the angle having a value related to the length difference between the guides of each subarray.

10. An antenna system comprising a pair of similar subarrays each comprising a plurality of dielectric channels having antenna apertures spaced along the path of desired maximum action, the apertures of one subarray being spaced in a direction perpendicular to said path and the apertures of the other subarray in a direction opposite said mentioned direction, and a translation device connected to said subarrays.

GEORGE E. MUELLER.

REFERENCES CITED UNITED STATES PATENTS Name Date Southworth July 9, 1940 Number

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