ABSTRACT This paper presents a switched beam patch antenna array fed by a 4 × 4 Butler Matrix (BM) working at 100 GHz for the first time, based on a novel metallic‐nanowire‐filled membrane technology (MnM). Butler matrix (BM) is well‐known as a simple passive beam‐forming network with low loss to realize switched beam. For this application, the MnM offers a straightforward and cost‐effective fabrication process for micro through‐substrate vias (TSVs), optimized for crossovers to ensure high performance up to 100 GHz. This includes high return loss, high isolation, low insertion loss, minimal amplitude and phase imbalance, and a compact size. Based on these features, a compact BM is implemented, targeting operation at 100 GHz. The first measurement on the semi‐BM demonstrator validates the design and fabrication with return loss > 17 dB and progressive phase steps with < 10% deviations from 95 to 105 GHz. The second measurement on the patch antenna array fed by the BM indicates rather symmetric switched beams at ±12° and ±45° with low side lobe level (SLL) of −14 and −7 dB. The four switched beams at 100 GHz have a decent gain from 3.3 to 5.5 dBi. The dimensions of the full array and the BM are 4.8 5.3 0.05 mm and 3.1 1.6 0.05 mm, respectively. The obtained results demonstrate that the proposed technology can be used for optimized versions of the Butler matrix, employing techniques to reduce side lobes and compensate for power variation.
Bovadilla et al. (Mon,) studied this question.