Multi-bursts space-time coding for active antenna systems

This paper proposes to transmit colored codes varying from burst to burst, with the same angular coverage, and to fuse the signals they produce over the different bursts. If the ambiguity functions of the colored codes have high sidelobes in different areas, a fusion process like a “K over N” criterion produces a global ambiguity function with reduced sidelobes while the main lobe keeps its narrow beam width (ratio 1/√2 on each axis, compared to a non-colored waveform). As an example, the fused codes can be non-colored, adjacent sub-bands, circulating codes or optimized phase codes. In this paper, a global ambiguity function is computed in the case of a 2-D active array antenna made of 4×4 transmit sub-arrays, and full Digital Beam Forming at Receive. 5 colored waveforms (non-colored, circulating codes, optimized codes) are fused by a criterion “3 over 5”. This case demonstrates the multi-colored signals fusion can reduce the ambiguity function sidelobes by more than 10 dB while keeping the main lobe as narrow as from a single colored waveform.