Abstract A method and apparatus for obtaining automatic, selective retrodirective performance from a circularly symmetric antenna array. This system may be employed in an active or passive manner and accomplishes selective retrodirectivity by manipulation of beam terminals of a multiple beam matrix which in turn controls a multimodal network. The combination of the two matrix networks provide N separate beams from the circular antenna array. Also, by providing gain networks, control of the reradiated beam pattern is possible. This system has the ability to identify the angle of incidence of any particular transmission, and is particularly suited for navigational beacon systems since the reradiated signal can provide bearing information in response to interrogation.
A circularly symmetric retrodirective antenna system comprising: circular symmetric antenna means having N radiators; and a first N X N Butler feed network means having N inputs and N outputs wherein the N outputs are sequentially connected to said antenna means; and a second similar N X N Butler feed network means having N inputs and N outputs wherein at least a portion of the N outputs of said second feed network means are connected to inputs of the first feed network; and unity reflection coefficient means connected to a plurality of said N inputs oF said second N X N feed network means with the remaining unconnected inputs being connected to matched loads such that retrodirectivity results from said antenna means in selected directions.
Claim 2
Dependent Claim
125 words
A circularly symmetric retrodirective antenna system comprising: circular symmetric antenna means having N radiators; and a first N X N Butler feed network means having N inputs and N outputs wherein the N outputs are sequentially connected to said antenna means; and a second similar N X N Butler feed network means having N inputs and N outputs wherein at least a portion of the N outputs of said second feed network means are connected to inputs of the first feed network; and unity reflection coefficient means connected to a plurality of said N inputs oF said second N X N feed network means with the remaining unconnected inputs being connected to matched loads such that retrodirectivity results from said antenna means in selected directions.
Claim 3
Dependent Claim
41 words
The device as claimed in claim 1 wherein circulator means are connected to a plurality of said input terminals of said second network means; and amplification means being coupled to said circulator means whereby active retrodirectivity results from said antenna means.