DSP Control Microwave-FFT Circuit for Multi-beam Phased Array Beam Forming

The onboard antenna beam forming network (BFN) of the next-generation communication satellites should realize multiple beam forming and antenna beam steering. An integrated, steerable, multiple beam phased array antenna beam forming network with a digital signal processing (DSP) circuit and a microwave fast Fourier transform (MW-FFT) circuit that realizes the above two functions is presented. The MW-FFT circuit generates multiple beams. The DSP circuit is an array of variable power dividers (VPD) and realizes beam steering. A VPD is implemented using a general purpose digital signal processor. A prototype circuit offering 15 beams and 16 elements is fabricated and its performance experimentally evaluated. Transmission characteristics of the BFN are measured, and antenna array factors calculated. Multiple beam forming and beam steering functions of the circuit are confirmed.