Broadband partially adaptive antenna using a new IIR fan filter

This paper develops a technique for designing a broadband partially adaptive antenna using a new recursive fan filter. The proposed structure consists of a multiple beamformer with the main beam directed toward the desired signal and a number of auxiliary beams of which only some are actually used. Each beamformer is a recursive fan filter and each fan filter is designed using an appropriate combination of recursive two-pole sections. This solution reduces the number of taps of the fan filter considerably. In spite of the reduction in coefficients of the broadband beamformer, interferences occurring in the sidelobes as well as the mainlobe of the desired pattern are cancelled effectively and this cancellation is essentially independent of frequency. The effects of signal-to-noise ratio on the improvement factor of the interference cancellation will also be studied by computer simulations.