Finite impulse response-filter-based RF-beamforming network for wideband and ultra-wideband antenna arrays

In this study, a wideband electronic beamforming concept applicable for ultra-wideband short pulse systems is derived and experimentally demonstrated. In particular, a finite impulse response (FIR)-filter-based beamforming network is configured such that an antenna array yields a desired radiation pattern within a predefined frequency range. An experimental verification of a wideband transmission system is presented for the frequency range from 1.5 to 2.0 GHz. The transmit system consists of a wideband power divider feeding a matrix of analogue FIR-filters. These FIR-filters control a circular antenna array of four elements. The receiver consists of a single antenna element. Measurements are performed in frequency domain using a vector network analyser. The results show an almost frequency independent radiation pattern with a half power beamwidth of 72 degrees and a maximum sidelobe level of -10 dB.