Polarization Reconfigurable Circular Patch Antenna with Multiple L-probes for Biomedical Application

This paper introduces a polarization reconfigurable circular patch antenna with multiple L-shaped feeding probes for biomedical applications. The proposed antenna is able to generate four linear polarizations as 0 degrees, + 45 degrees, 90 degrees and -45 degrees to overcome the multi-path distortion and polarization mismatching in body-centric wireless communication system (BWCS). To realize this characteristic, we designed a reconfigurable multiple L-probes feeding structure to excite a circular patch. In this design, four pairs of L-shaped probes are evenly located below the patch with the interval of angle 45 degree and excited by an output reconfigurable feeding network. The excitation port can be altered among the four ports by controlling the PIN diodes as RF switches connected between the microstrip feeding lines. As the result, four polarizations are switchable as each polarization is corresponding to a specific excitation port. The proposed antenna exhibits good performance as wideband, low profile, simple structure and stable gain with low cross polarization for all operating modes.