Quadruple-Differentially-Driven Offset-Probe- Fed Patch Antenna for On-Antenna Power Combining

In this paper, a novel quadruple differentially driven offset probe fed patch antenna is introduced to extend the on-antenna power combining (OAPC) capabilities. This original design is based on the feeding of the two fundamental resonating modes of a square patch using offset differential probe pairs. Polarization diversity is obtained changing the relative phase difference between the differential driving signals. Using two orthogonally arranged offset differential pairs (each driving one of the two resonating modes), a four-port driven patch antenna (4DPA) is achieved. Then, mirror-duplicating the 4DPA feeding differential pairs (i.e., each resonating mode being then driven by two offset differential pairs), an eight-port driven patch antenna (8DPA) is obtained. For those structures, the offset probe pair common mode (CM) parasitic effect is studied. Then, mitigating technics based on the CM impedance control are introduced. One of them is implemented in 4DPA and 8DPA demonstrators using unbalanced commercial power amplifiers. Combining power directly into the antenna with up to eight ports in this work, improved efficiency, higher transmitted power, smaller associated monolithic microwave integrated circuits (MMIC) and enhanced heat dissipation are achieved compared to the alternative on-circuit power combining technics. As a proof of concept and to compare performance, passive and active demonstrators of reference one-port driven patch antennas (1DPA), 4DPAs and 8DPAs operating at 2.45 GHz are designed, fabricated and measured. The simulation and experimental results validate the proposed on-antenna combining technic, which is believed by the authors to be of particular interest to enhance performance of radar and communication silicon-based active antenna arrays.