Coupling reduction between circularly polarized patch antennas with spiral resonator structure

Abstract

We utilize a spiral resonator (SR) for reducing the mutual coupling between two closely spaced circularly polarized (CP) patch antennas. Each antenna element has a physical size of 40 mm × 40 mm and its center operating frequency is 2.491 GHz with a gain of 5.2 dBic. The designed SR, which can effectively realize a band-stop effect at the operating frequency, is placed between the closely spaced CP antennas with an inter-element separation of 40 mm (approximately 0.33 λ 0 , where λ 0 is free space wavelength at 2.491 GHz) to improve their isolation. The simulation results show that the isolation has been improved by 18 dB with the employment of the SR. Furthermore, loading SR has minor impact on the radiation characteristics of the antenna.