Concentric circular compound reconfigurable microstrip patch antenna for wireless applications

Abstract

The article presents a concentric circle compound reconfigurable (frequency, polarization, and pattern) microstrip antenna for lower-S band (2.0 GHz-3.0 GHz) applications. Varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.94pF (6 V), the resonant frequency of the antenna can be tuned from 2.10 GHz to 2.90 GHz (34.52% tunable bandwidth). These diodes are incorporated to bridge the gap between the circle and ring of concentric geometry. The arc slots and C-shape wings are used for polarization and pattern reconfiguration, respectively. The arc slots are etched from the edge of circle geometry and loaded with RF PIN diodes to provide the different polarization states: linear polarization, left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP). Simultaneously, the pattern reconfigurability can be attained with C-shape wings, placed around the concentric circle geometry; hence, patterns are tilt at 0° and ± 50°. The pattern reconfigurability also controlled through the RF PIN diodes. The designed antenna is experimentally verified and shows the maximum gain of 4.31 dBic and 4.04 dBi in polarization and pattern reconfigurable mode, respectively. Besides, it provides an excellent axial ratio (<3 dB) and stable radiation patterns. Therefore, the proposed compound reconfigurable antenna can be served for a future communication system and improves the signal quality without any destruction.