Dual Polarized Printed Circuit Dipole Antenna Array

Abstract

An antenna array is provided by stacking two PC boards in a superimposed relationship above a housing acting as a ground plane. Each of these two PC boards contain thereon a symmetrical arrangement of photo etched or printed mat-strip power division networks and dipole elements providing linear polarization, the dipole elements on one PC board being oriented with the dipole elements on the other PC board to provide orthogonal linear polarizations. A ground plane for the dipole elements on the upper PC board is provided by parallel, spaced conductive members in a superimposed, parallel relationship with the dipole elements of the upper PC board. In one embodiment, the ground plane conductive members are provided by conductive strips on a third PC board disposed between the first two PC boards. In another embodiment, the same third PC board is disposed between the lower PC board and the housing ground plane therefore. In a third embodiment, the ground plane conductive members are formed as ridges on the housing ground plane. The dipole elements and the power division networks of the first two PC boards and the conductive members are so oriented that they are mutually transparent to radiation to and from the dipole elements of the first two PC boards. The symmetrical dipole elements on each of the first two PC boards are fed by a balanced, symmetrically branched power division mat-strip network carried by the associated board and a combined balun and power divider coupling an input waveguide to the balanced line network. Each combined balun and power divider includes a coaxial transmission line having its center conductor connected directly to a mat-strip conductor extending radially in two directions from the center conductor to the mat-strip network, this latter mat-strip having the same width as the mat-strip conductors of the network, and its outer conductor connected to a mat-strip conductor connected to the mat-strip network having a greater width than the mat-strip conductors of tne network. The mat-strip conductors of the network includes at the branching locations reflectionless impedance transformers formed by a predetermined length of predetermined mat-strip width different than the given width.

Description

BACKGROUND OF THE INVENTION

This invention relates to antenna arrays and more particularly to antenna arrays employing mat-strip and printed circuit techniques.

The term "mat-strip" as employed herein is defined as a photo etched or printed balanced transmission line printed on opposite surfaces of a printed circuit (PC) board in such a manner that both conductors are superimposed, are equal in width and are equal in length. This is in contrast to a stripline transmission line which is an unbalanced transmission line requiring two ground planes one above and one below a single conductive strip and to a microstrip transmission line which consists of a conductive strip above a ground plane having a much greater width than the conductive strip. A microstrip transmission line is analogous to a two wire line in which one of the wires is represented by the image in the ground plane of the wire that is physically present. Another way of expressing what a mat-strip transmission line is to state that it is a balanced transmission line in which the image wire of a microstrip transmission line has materialized and the ground plane of a microstrip transmission line has been removed.

An antenna dipole element in mat-strip technique consists of one half of the dipole element (one wing) being disposed on one surface of a PC board having one end thereof connected to one conductor of a mat-strip transmission line and the other half of the dipole element (the other wing) being disposed on the other surface of the PC board having one end thereof connected to the other conductor of the same mat-strip transmission line. A ground plane is associated with the dipole elements (it has no function in the mat-strip transmission line) to ensure that the radiation from the dipole element is from one surface of the PC board, namely, the surface of the PC board removed from the ground plane.

U.S. Pat. No. 2,962,716 issued to H.F. Engelmann and assigned to International Telephone and Telegraph Corporation discloses therein a linearly polarized antenna array including dipole elements which are parallel fed by a mat-strip transmission line network which, in turn, is fed by a "single ended" balun. The single ended balun includes a coaxial line having its center conductor connected to one conductor of a mat-strip conductor extending radially in one direction from the center conductor to the antenna feeding power division network while the other conductor of this radially extending mat-strip conductor is coupled to the outer conductor of the coaxial line. Employing the single ended balun arrangement the power feed to the antenna array is limited by the physical width of the mat-strip transmission line extending in one direction radially from the coaxial line. Also at higher frequencies, such as X-band or above, the single ended balun arrangement will radiate because an unbalanced line (coax) is connected "single ended" to a balanced line (mat-strip).

SUMMARY OF THE INVENTION

An object of the present invention is to provide a dual (right and lefthand) circularly polarized antenna array employing the techniques disclosed in the above cited patent for the antenna arrays involved.

Another object of the present invention is to provide an antenna array having two sub-arrays orthogonally disposed which by appropriate selection of the feeding arrangements thereto will enable the antenna array to be employed for more than just a circularly polarized antenna array, such as radiation and reception of 45.degree. polarized radiation, reception on one sub-array with one polarization and transmission on the other sub-array with a polarization orthogonally related to said one polarization and the like.

Still another object of the present invention is to provide as an integral part of the balanced mat-strip power division transmission line network for feeding the antenna arrays, a balun arrangement which will substantially increase the amount of power that may be distributed to the antenna elements with respect to that amount of power capable of being handled in the arrangement disclosed in the cited patent.

A further object of the present invention is to provide an antenna array employing two PC boards each containing thereon a linearly polarized dipole element array which are symmetrically disposed in each quadrant of the PC board, the dipole elements of one PC board being oriented in a 90.degree. phase relationship with the dipole elements of the other PC board, and further providing a "double ended" balun which also functions as a power division network so as to double the amount of power feed to the associated antenna array with respect to the amount of power that can be fed to the antenna array by the single ended balun disclosed in the cited patent.

Still a further object of this invention is the ability to provide the two printed circuit linearly polarized antenna arrays and their power dividing fed network from the same art work.

A feature of this invention is to provide an antenna array comprising a first plurality of dipole elements; a first ground plane superimposed relative to and associated with the first plurality of elements; a first power distributor network associated with the first plurality of elements and disposed in a superimposed relation to the first ground plane; a second plurality of dipole elements; a second ground plane superimposed relation to and associated with the second plurality of elements; and a second power distribution network associated with the second plurality of elements and disposed in a superimposed relation to the second ground plane; each of the first and second plurality of elements being fed at its electrical center by their associated one of the first and second distribution networks; said first plurality of elements, ground plane and power distribution network being disposed in a superimposed relation to and oriented in relation with the second plurality of elements, ground plane and power distribution network to be mutually transparent with respect to radiation to and from both the first and second elements.

A further feature of this invention is to provide an antenna array comprising a first PC board including thereon at least a first pair of dipole elements each having a given orientation; a second PC board including thereon at least a second pair of dipole elements each having an orientation orthogonal to the given orientation, the second PC board being coextensive with and being disposed in spaced, parallel relation to the first PC board, the second pair of dipole elements being in a superimposed relationship with respect to the first pair of dipole elements; a conductive body coextensive with, parallel to and spaced a predetermined amount from one surface of one of the first and second PC boards to provide a ground plane therefore; and at least a pair of spaced, parallel conductive members each having an orientation parallel to and in a superimposed relation with a different one of the dipole elements on the other of the first and second PC boards and spaced from the other of the first and second boards by the predetermined amount to provide a ground plane therefor and yet be transparent to the radiation to or from the dipole elements on the one of the first and second PC boards.

Another feature of this invention is the provision of a symmetrical energy coupling network for radiating elements in the form of conductive strips disposed symmetrically on a PC board providing a symmetrical antenna array comprising a balanced power division transmission line network disposed on the PC board extending symmetrically and radially in two directions from adjacent the point of symmetry of the radiating elements to provide a symmetrical energy coupling relation with the radiating elements, and a combined balun and power divider coupled to the network including a coaxial transmission line disposed perpendicular to the PC board adjacent the point of symmetry, the coaxial line having an outer conductor and a center conductor extending through the PC board to one surface thereof, a first strip conductor disposed on the one surface of the PC board connected directly to and extending radially in two directions from the center conductor for connection to the inputs of the network, the first strip conductor having a given width, and a second strip conductor disposed on the other surface of the PC board in a superimposed relation with the first strip conductor and connected between the outer conductor and the inputs of the network, the second strip conductor having a width greater than the given width.

BRIEF DESCRIPTION OF THE DRAWING

The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a plan view of the top most mat-strip linearly polarized antenna array having certain portions thereof removed to expose (1) the lower most mat-strip linearly polarized antenna array, (2) the parallel strip ground planes for the dipole elements of the top most antenna array and (3) the bottom conductor of the dipole elements and the mat-strip type balanced power division transmission line network of the top most antenna array in accordance with the principles of this invention;

FIG. 2 is a cross-section of FIG. 1 taken along line 2--2;

FIG. 2A is a cross-section of FIG. 2 taken along line 2A--2A;

FIG. 3 is an enlarged plan view of one of the quadruple dipole element arrangements of either of the linear polarized arrays of FIG. 1;

FIG. 4 is a cross-sectional view of FIG. 3 taken along line 4--4;

FIG. 5 is a cross-sectional view of FIG. 1 taken along line 2--2 illustrating an alternative relative location of the three PC boards in accordance with the principles of this invention;

FIG. 6 is a cross-sectional view of FIG. 1 taken along line 2--2 illustrating an alternative ground plane for the upper most of PC board array in accordance with the principles of this invention; and

FIG. 7 is a plan view of the FIG. 6 taken along line 7--7.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-4, there is illustrated therein a stacked or sandwich type arrangement of PC type linearly polarized arrays and associated ground planes to enable the achievement of a dual circularly polarized antenna array when energy is appropriately fed thereto in accordance with the principles of this invention. The antenna array includes a dielectric sheet 1 having disposed thereon by PC techniques dipole antenna elements 2 in the form of two sections (dipole "wings") 3 and 4, section 3 being disposed on the upper surface 5 of sheet 1 and section 4 being disposed on the lower surface 6 of sheet 1. As illustrated, this array includes a plurality of pairs of dipole elements 2 interconnected for symmetrical parallel power feed by mat-strip type balanced power division transmission line network 7 including various balanced mat-strip type conductors 8 and 9 to provide power division and parallel feeding of the groups of dipole elements. The linearly polarized dipole element array on sheet 1 is symmetrical in all quadrants as are their transmission line networks 7.

The cut away portion 10 of sheet 1 has exposed the lower conductive strips 12a of a mat-strip type transmission line network 7 and the lower sections 4 of dipole elements 2. It should be noted that as in the cited patent the mat-strip conductors of balanced transmission line network 7 are formed by two strip conductors, such as conductor 11 disposed on surface 5 of sheet 1 and strip conductor 12 superimposed with respect to conductor 11 on the surface 6 of sheet 1. Referring to FIG. 4, it will be seen that section 3 (a dipole "wing") is a continuation of conductor 11b and that section 4 (a dipole "wing") is a continuation of conductor 12b when these elements are formed by PC techniques.

The lower most linearly polarized antenna array is disposed, by PC techniques on dielectric sheet 13 and has the same symmetry as the antenna array on sheet 1 with the modification that this linearly polarized array has its dipole elements 2' oriented 90.degree. with respect to dipole elements 2 in the array on sheet 1. This lower array on member 13 is parallel fed by a mat-strip type balanced power division transmission line network 7' which is identical to network 7 on member 1, but also oriented in a 90.degree. relationship with respect thereto.

The ground plane for the linearly polarized antenna array on sheet 13 is provided by the metallic housing 14 while the ground plane for the antenna array on sheet 1 is provided by a third PC board including dielectric sheet 15 having disposed thereon dielectric strips 16 being oriented and disposed thereon to be parallel to and in a superimposed relationship with dipole elements 2 of the top most linearly polarized array on sheet 1. In the embodiment illustrated in FIG. 2, this ground plane is disposed between the linearly polarized arrays on PC boards 1 and 13.

The array on sheet 13 must be spaced from the ground plane 14 by a dimension C = .lambda. /4. Likewise, the spacing between the array on sheet 1 and the ground plane provided by parallel conductor 16 is also a dimension A = .lambda./4. The .lambda./4 spacing (dimensions A and C) are nominal values for the operating frequency range of the antenna array.

Due to the presence of the parallel strip 16 ground plane between the two linearly polarized antenna arrays, the dimension B is not critical and, therefore, close tolerances do not have to be maintained in the process of manufacturing the array of this invention. This is due to the fact that the wave velocity both in free space and in the coaxial balun structure are nearly equal. Thus the quadrature phasing necessary to derive circular polarization is not significantly altered by the displacement dimension B.

In a reduction to practice the dielectric sheets 1, 13 and 15 had a thickness M = 1/16 inches. The dimension of the dipole elements 2 and 2' has a length F which is less than .lambda./2 and a width N wider than is normally found in a .lambda./2 dipole element at the operating frequency being considered which is in the order of 8 gigahertz. Dipole elements 2 and 2' are effectively a .lambda./2 in length, but are shorter and fatter than normal to provide an improved bandwidth characteristic for the antenna array of this invention. The spacing J between the centers of dipole elements 2 and 2' is J = 0.6 to 0.8.lambda., for presently operating antennas. This spacing is made optimum for a particular application, but it is not critical. The dimension between the ends of adjacent dipole elements 2 and 2', D and K, are not critical nor is the spacing E between the side of adjacent pairs of dipole elements critical. These dimensions may be adjusted to permit proper impedance transformation in network 7 and 7' and also to enable more elements to be placed upon the associated dielectric sheet.

It will be noted that networks 7 and 7' include in each of the strip conductors of this balanced transmission line network decreased width portions and increased width portions at the branching positions or locations thereof. The decreased width portions having dimensions G and H and the increased width portions having dimensions I and L, FIG. 3, are each .lambda./4 to provide a reflectionless power transformation between the transmission line sections themselves and from the transmission line sections to the dipole elements 2 and 2'.

The spacing between sheets 1, 13 and 15 and ground plane 14 are maintained to the appropriate predetermined value by the employment of bolts 17 extending through ground plane 14 and sheets 1, 13 and 15 with appropriate length spacers or stand-offs 18, 19 and 20 disposed thereon to maintain the desired spacing of the stacked arrangement. In addition to these bolts and separators, the coaxial transmission line portion of the combined balun and power dividing devices, to be described hereinbelow, also cooperate in maintaining the desired separation of the stacked members. These separations can also be maintained by frame structures made of low density foam. This would lend itself to a bonded sandwich construction.

As illustrated in FIG. 1 and in greater detail in FIG. 3, dipole elements 2 and 2' are configured so that sections 3 and 4 have a substantially constant width until just prior to connection to network 7 where it is tapered, such as at portion 21. The purpose of this taper 21, the length and taper of which is empirically determined, is to provide better radiation efficiency. It has been determined in addition through experimentation that a triangular shaped section 3 and 4 for elements 2 and 2' will also provide desired radiation efficiency and also a broader bandwidth.

As disclosed in FIG. 2, the dielectric between the various sheets 1, 13, and 15 and ground plane 14 is air dielectric. However, it is within the scope of this invention to incorporate a low loss honeycomb or foam dielectric material in between the various horizontal members. If this type of dielectric is employed, bolts 17 and stand-offs 18, 19 and 20 can be dispensed with, since the foam or honeycomb dielectric material would then provide the desired separation between the various horizontal members.

The transmission networks 7 and 7' are symmetrically fed from a combined balun and power divider and is of the double ended balun type. Energy is coupled to each of the arrays by similar waveguides 22 and 22a coupled to the 90.degree. and 0.degree. output ports, respectively of a 90.degree. short slot hybrid (not shown) so that each array is fed in a 90.degree. phase relationship to provide circular polarization. The unbalanced to balanced transformation is obtained by the combined balun and power divider in accordance with the present invention which includes similar coaxial transmission lines 23 and 23a having inner conductors 24 and 24a, respectively, extending through members 13 and 1, respectively, for electrical contact with strip conductors 25 and 25a, respectively. Conductors 25 and 25a each extending radially in two directions from center conductors 24 and 24a with the ends thereof being respectively connected to the inputs to network 7', such as at points 28 and 29. (FIG. 1), and the inputs to network 7, such as the points 28a and 29a (FIG. 1); The outer conductors 26 and 26a of coaxial transmission lines 23 and 23a is physically supporting and in electrical contact with strip conductors 27 and 27a, respectively having the configuration as shown in FIG. 1 which obviously is wider than the width of conductors 25 and 25a and the conductors forming networks 7 and 7'. Thus, the combined balun and power divider of this invention provides a direct transition from waveguides 22 and 22a to the balanced mat-strip of network 7 and 7'. It also provides a positive mechanical connection to the balanced line of the printed array without the use of solder joints and, in addition, and more importantly provides an immediate power division with a relatively large heat sink formed by conductor 27 thereby enabling the feeding of greater power into networks 7 and 7'.

The purpose of the circuitous path followed by the input conductors of network 7' leading from the combined balun and power divider is to reduce the number of dipole elements that must be eliminated from both the arrays to enable the transformation from an unbalanced to a balanced line and also the immediate power division provided by the double ended balun and power divider arrangement, and also to provide equi-phase dipole excitation by equal length paths to all dipoles.

The conductors of networks 7 and 7' and dipole elements are composed of conductive material, such as copper, copper clad material or the like. The dielectric sheets 1, 13 and 15 are composed of a low loss dielectric, such as Tellite, Rexilite, Z-Tron and Duroid. The latter two low loss dielectric materials are also high temperature materials and, of course, would be particularly applicable to the present invention under high temperature conditions.

Due to the orientation of the dipole arrays on sheets 1 and 13 and the orientation of ground strip conductors 16, the diode elements 2 and the balanced transmission lines of network 7 and the strip ground conductors 16 are invisible or transparent to radiation to and from dipole elements 2' on sheet member 13.

As pointed out hereinabove the antenna array of this invention may be circularly polarized provided the balun-power divider combination of each linear array are fed in a 90.degree. phase relationship, such as by a short slot hybrid. In addition to circular polarization, the orthogonally related linear arrays can be used in other applications. For instance, a 45.degree. polarized antenna pattern can be achieved by proper feeding of the balun-power divider combination of each array, or one linearly polarized array can be employed for transmission and the other linearly polarized array can be employed for receiving provided the feed to the balun-power divider combination is appropriate. Other applications to which the sandwich array of the present invention will be applicable with proper feed will become apparent to those skilled in the art.

The transmission networks 7 and 7' are split in a binary fashion and have equal length mat-strip lines thereby enabling the dipole elements to be fed with equal amplitude and equal phase. However, it is possible to arrange networks 7 and 7' to be split or divided on a ternary quadruple or other basis and to have unequal length mat-strip lines resulting in many different relationships between amplitude and phase excitation of the dipole elements. This will enable achieving many different types of radiation patterns.

Referring to FIG. 2, the ground plane for the array disposed on sheet 1 is provided by conductive strips disposed on sheet 15 which is positioned between the sheets 1 and 13 carrying the two linearly polarized arrays. This is not a critical location for the ground plane carried by sheets 15. In fact as illustrated in FIG. 5, sheet 15 may be disposed between the housing 14 and the sheet 13. This will result in a still more compact sandwich construction than that shown in FIG. 2.

In addition, there is available still another embodiment for the ground plane of the linearly polarized array disposed on sheet 1. This embodiment is illustrated in FIGS. 6 and 7 and eliminates the third sheet 15. In the embodiment of FIGS. 6 and 7, the ground plane for the dipole element disposed on sheet 1 is provided by parallel spaced ridges 16a disposed on housing 14 oriented to be parallel to and in a superimposed relationship with dipole elements 2 on sheet 1. This arrangement will result in still a more compact sandwich construction than possible with the embodiments of FIG. 2 and 5.

The antenna array of this invention provides a construction which is a compact sandwich construction, is extremely rugged, is inexpensive and is of minimal thickness. Another advantage is that both the upper and lower antenna arrays including network 7 and 7' are fabricated by PC techniques employing the same art work. As a result, the phase errors introduced by the printed arrays is minimized when using the modular concept to build larger arrays and, in addition, the manufacturing costs are minimized especially if many modules are to be constructed.

While we have described above the principles of our invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of our invention as set forth in the objects thereof and in the accompanying claims.

Claims

1. An antenna array comprising:

a first plurality of dipole elements;

a first ground plane superimposed relative to and associated with said first plurality of elements;

a first power distribution network associated with said first plurality of elements and disposed in a superimposed relation to said first ground plane;

a second plurality of dipole elements;

a second ground plane superimposed relative to and associated with said second plurality of elements; and

a second power distribution network associated with said second plurality of elements and disposed in a superimposed relation to said second ground plane;

each of said first and second plurality of elements being fed at its electrical center by their associated one of said first and second distribution networks;

said first plurality of elements, ground plane and power distribution network being disposed in a superimposed relation to and oriented in relation with said second plurality of elements, ground plane and power distribution network to be mutually transparent with respect to radiation

2. An antenna array comprising:

a first printed circuit board including thereon at least a first pair of dipole elements each having a given orientation;

a second printed circuit board including thereon at least a second pair of dipole elements each having an orientation orthogonal to said given orientation, said second board being coextensive with and being disposed in spaced, parallel relation to said first board, said second pair of dipole elements being in a superimposed relationship with respect to said first pair of dipole elements;

a conductive body coextensive with, parallel to and spaced a predetermined amount from one surface of one of said first and second boards to provide a ground plane therefore; and

at least a pair of spaced, parallel conductive members each having an orientation parallel to and in a superimposed relation with a different one of said dipole elements on the other of said first and second boards and spaced from said other of said first and second boards by said predetermined amount to provide a ground plane therefore and yet be transparent to the radiation to or from said dipole elements on said one

3. An antenna array according to claim 2, further including

a first balanced power division transmission line carried by said first board symmetrically coupled to each of said dipole elements of said first pair of dipole elements, and

a second balanced, power division transmission line carried by said second board symmetrically coupled to each of said dipole elements of said second

4. An antenna array according to claim 2, wherein

each dipole element of said first and second pair of dipole elements includes

a first conductive radiating section disposed on one surface of the associated one of said first and second boards, and

a second conductive radiating section disposed on the other surface of said

5. An antenna array according to claim 4, further including

a symmetrical, balanced, power division transmission line network carried by each of said first and second boards symmetrically coupled to each dipole element of the associated one of said first and second pair of dipole elements for equal power distribution,

each of said networks including

a first conductive transmission line element disposed on said one surface of said associated one of said first and second boards connected to said first radiating section, and

a second conductive transmission line element disposed on said other surface of said associated one of said first and second boards connected

6. An antenna array according to claim 2, wherein

said pair of conductive members includes

a third printed circuit board having thereon at least a pair of spaced, parallel conductive strips, said third board being disposed between said

7. An antenna array according to claim 2, wherein

said pair of conductive members includes

a third printed circuit board having thereon at least a pair of spaced, parallel conductive strips, said third board being disposed between said

8. An antenna array according to claim 2, wherein

said pair of conductive members includes

a pair of spaced, parallel conductive ridges extending from one surface of said conductive body towards said other of said first and second boards.

9. An antenna array according to claim 2, wherein

said first board includes

N of said first pair of dipole elements symmetrically disposed on said first board, where N is an integer greater than one;

said second board includes

N of said second pair of dipole elements symmetrically disposed on said second board in a superimposed relationship with respect to said plurality of said first pair of dipole elements; and

said ground plane for said other of said first and second boards include

a plurality of parallel, spaced conductive members, each of said members being disposed parallel to and in a superimposed relation with all those dipole elements aligned along a given line on said other of said first and

10. An antenna array according to claim 9, further comprising

a mat-strip type balanced power division transmission line network disposed on each of said first and second boards extending symmetrically and radially in two directions from adjacent the point of symmetry to provide a symmetrical energy coupling relation with the associated one of said N of said first and second pair of dipole antennas, and

a combined balun and power divider coupled to each of said networks including

a coaxial transmission line disposed perpendicular to the associated one of said first and second boards adjacent said point of symmetry, said coaxial line having an outer conductor and a center conductor extending through said associated one of said first and second boards to one surface thereof,

a first strip conductor disposed on said one surface of said associated one of said first and second boards connected directly to and extending radially in two directions from said center conductor for connection to the inputs of said network, said first strip conductor having a given width, and

a second strip conductor disposed on the other surface of said associated one of said first and second boards in a superimposed relation with said first strip conductor and connected between said outer conductor and said inputs of said network, said second strip conductor having a width greater

11. An antenna array according to claim 10, wherein

each of said transmission line networks including

a third strip conductor disposed on said one surface of said associated one of said first and second boards having said given width and one end thereof coupled to one end of said first strip conductor,

a fourth strip conductor disposed on said one surface of said associated one of said first and second boards having said given width and one end thereof coupled to the other end of said first strip conductor.

a fifth strip conductor disposed on the other surface of said associated one of said first and second boards having said given width and one end thereof coupled to said second strip conductor, said fifth strip conductor being disposed in a superimposed relation with said third strip conductor, and

a sixth strip conductor disposed on said other surface of said associated one of said first and second boards having said given width and one end thereof coupled to said second strip conductor being disposed in a

12. An antenna according to claim 11, wherein

said third and fifth strip conductors and said fourth and sixth strip conductors are symmetrically branched at predetermined locations to provide said energy coupling relation, and

said third and fifth strip conductors and said fourth and sixth strip conductors each include a different predetermined width than said given width for a predetermined length at said predetermined locations to provide reflectionless energy transformation in said transmission line

13. An antenna array according to claim 9, wherein

said plurality of conductive members includes

a third printed circuit board having thereon a plurality of spaced, parallel strips, said third board being disposed between said first and

14. An antenna array according to claim 9, wherein

said plurality of conductive members includes

a third printed circuit board having thereon a plurality of spaced, parallel strips, said third board being disposed between said conductive

15. An antenna array according to claim 9, wherein

said plurality of conductive members includes

a plurality of spaced, parallel ridges extending from one surface of said

16. In a symmetrical antenna array having radiating elements in the form of conductive strips disposed symmetrically on a printed circuit board, a symmetrical energy coupling network for said radiating elements comprising:

a mat-strip type balanced power division transmission line network disposed on said board extending symmetrically and radially in two directions from adjacent the point of symmetry of said radiating elements to provide a symmetrical energy coupling relation with said radiating elements; and

a combined balun and power divider coupled to said network including

a coaxial transmission line disposed perpendicular to said board adjacent said point of symmetry, said coaxial line having an outer conductor and a center conductor extending through said board to one surface thereof,

a first strip conductor disposed on said one surface of said board connected directly to and extending radially in two directions from said center conductor for connection to the inputs of said network, said first strip conductor having a given width, and

a second strip conductor disposed on the other surface of said board in a superimposed relation with said first strip conductor and connected between said outer conductor and said inputs of said network, said second

17. The symmetrical energy coupling network according to claim 16, wherein

said transmission line network includes

a third strip conductor disposed on said one surface of said board having said given width and one end thereof coupled to one end of said first strip conductor,

a fourth strip conductor disposed on said one surface of said board having said given width and one end thereof coupled to the other end of said first strip conductor, a fifth strip conductor disposed on the other surface of said board having said given width and one end thereof coupled to said second strip conductor, said fifth strip conductor being disposed in a superimposed relation with said third strip conductor, and

a sixth strip conductor disposed on said other surface of said board having said given width and one end thereof coupled to said second strip conductor, said sixth strip conductor being disposed in a superimposed

18. The symmetrical energy coupling network according to claim 17, wherein

said third and fifth strip conductors and said fourth and sixth strip conductors are symmetrically branched at predetermined locations to provide said energy coupling relation, and

said third and fifth strip conductors and said fourth and sixth strip conductors each include a different predetermined width than said given width for a predetermined length at said predetermined locations to provide reflectionless energy transformation in said transmission line network.