Reconfigurable multi-slot antenna for bio-medical applications

We present a polarization- reconfigurable multislot antenna with four switchable linear polarizations (as 0°, ± 45° and 90°) for implant communications. The design is based on four bow-tie shaped slots acting as radiators etched on a circular metallization plane with 45° rotated sequential arrangements. RF switches based on PIN diodes are connected across each slot in order to modify the radiators polarization. We apply a differential source to feed the slot antenna through a ground-tapered Balun. In order to obtain a broadside radiation pattern, a reflector is placed at the quarter-wave distance below the radiator. Measured results are showing that the realized multi-slot antenna can generate four switchable linear polarization states with wide bandwidth and stable gain. This polarization diversity feature makes the proposed antenna highly attractive for implant and body-centric wireless communication systems for minimizing the multi-path distortion and polarization mismatching in the wireless channels.

I. Introduction

Reconfigurable antennas have become more and more popular with the rapid development of modern wireless communication systems. Antennas with circular or linear polarization reconfigurable features have many noticeable advantages such as enhancing the communication channel capacity, avoiding multipath interference, and being capable of polarization coding [1]–[3]. Many studies have been conducted in the domain of polarization reconfigurable antennas, as reviewed in [4]–[8]. As most of the designs are based on modifying microstrip patch radiators, the operating bandwidths are commonly narrow. In addition, none of these designs can realize four switchable linear polarizations. Antennas with polarization diversity are very promising to be used as receiving antenna in order to compensate for polarization mismatch due to improper orientations of transmitters.