Adaptive Control Algorithm for the ESPAR Antenna
Blagovest SHISHKOV and OHIRA Takashi
The electronically steerable passive array radiator (ESPAR) antenna
performs analog aerial beamforming. Unlike conventional adaptive antennas, it
has only a single output port for observation. This lack of spatial information
and, what is even more important, the highly nonlinear dependence of antenna output
on adjustable reactances means the techniques of conventional beamforming cannot
resolve the problem. ATR has developed a novel approach to adaptive beamforming
of the ESPAR antenna as a nonlinear spatial filter by variable parameters. The
control algorithm is based on stochastic approximation theory. It allows the ESPAR
antenna to steer its beam and nulls automatically in a complex signal environment
consisting of signal of interest, co-channel interferences and additive noise.
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