Abstract Several small Butler matrices are interconnected in a manner to replace a large Butler matrix employed in a beam forming and scanning network for a circular antenna array. This system of Butler submatrices (a set of low order Butler matrices simulating a single higher order Butler matrix) permits a reduction in the size of an existing feed system without any sacrifice in the 360* beam steering capability. Also this system produces only a minimal loss in beamwidth. A major difference between this system and the systems of the prior art is the number of modes available. For this instant submatrix feed system, the number of available modes is at most, one-half of that in the well known single Butler matrix system. The additional modes in the single Butler matrix system of the prior art are ''''high order'''' modes and have generally produced poor quality far field patterns. As a result only a small percentage of these modes could be used in practice. Hence for most applications, the two systems provide essentially the same performance with the submatrix feed system being more economical since it is simpler, requires less hardware, and is more efficient in that all but one of the available modes are high quality modes.
In a beam forming and scanning network for a circular array of antennas, each antenna being connected to an output of multimodal means, a plurality of the input means of said multimodal means being serially coupled to fixed phase shifters, power dividers, and variable phase shifters, the improvement comprising: a plurality of discrete Butler matrices employed as said multimodal means between the antennas and fixed phase shifters.
Claim 2
Dependent Claim
67 words
In a beam forming and scanning network for a circular array of antennas, each antenna being connected to an output of multimodal means, a plurality of the input means of said multimodal means being serially coupled to fixed phase shifters, power dividers, and variable phase shifters, the improvement comprising: a plurality of discrete Butler matrices employed as said multimodal means between the antennas and fixed phase shifters.
Claim 3
Dependent Claim
82 words
In a beam forming and scanning network for a circular array of N antennas, each antenna being connected to an output terminal of multimodal means, a plurality of input mode terminal means of said multimodal means being serially coupled to fixed phase shifters, power dividers, and variable phase shifters, the improvement comprising: B number of (C X C) order discrete Butler submatrices having C number of outputs employed as said multimodal means between the antennas and fixed phase shifters wherein B.C N.
Claim 4
Dependent Claim
82 words
In a beam forming and scanning network for a circular array of N antennas, each antenna being connected to an output terminal of multimodal means, a plurality of input mode terminal means of said multimodal means being serially coupled to fixed phase shifters, power dividers, and variable phase shifters, the improvement comprising: B number of (C X C) order discrete Butler submatrices having C number of outputs employed as said multimodal means between the antennas and fixed phase shifters wherein B.C N.
Claim 5
Dependent Claim
18 words
The device as claimed in claim 1 wherein the highest mode terminal is terminated in a matched load.
Claim 6
Dependent Claim
94 words
The device as claimed in claim 1 wherein the first terminal of each submatrix is sequentially connected around the circular array until the first terminal of submatrix B is connected to terminal B of the array; the B + 1 element of the array is connected to the second terminal of the first submatrix, and the second terminal of each subsequent submatrix is sequentially connected around the array until the second terminal of submatrix is connected to array element 2B; and until the C terminal of submatrix B is connected to array element N.