Dual-Mirror Wide Angle Quasi-Optical Beamformer in PCB Technology for Satcom Applications

This paper presents a novel quasi-optical beamformer in multi-layer PCB technology for feeding Low Earth Orbit (LEO) arrays to generate multiple beams over wide fields of view in K - band (17.3 - 20.2 GHz). The quasi-optical system adopts a dual-mirror configuration to reduce the size of the beamformer and provides the required amplitude and phase illumination to the array. A Physical Optics tool is adopted for the optimization of the shape of the dual-mirror system and location of the input sources. To each source in the focal plane of the quasi-optical system corresponds a pointing direction of the radiated beam in the far field. The realized beamformer feeds in phase and amplitude 28 elements of a linear array with 23 independent beams over ±55° field of view with side lobe levels below -15 dB and beam crossover above -3.9 dB. The true time delay behavior of the beamformer guarantees stable pointing directions in the considered band of operation. The reflection coefficients at the input sources are below -10 dB whereas mutual couplings remain below -19 dB.