Dual diversity-enabled circularly polarized MIMO antenna based on a four-port ring cylindrical dielectric resonator

Abstract This study presents a novel circularly polarized (CP) multiple-input multiple-output (MIMO) antenna system that integrates four ring cylindrical dielectric resonators (RCDRs) mounted on four rectangular FR-4 substrates, strategically arranged to form a box-like structure. This assembly is positioned over a disc-shaped FR-4 substrate, which serves as a shared ground plane for the four rectangular RCDR antennas (RCDRAs). Each antenna element is excited through a cross-shaped aperture in the rectangular ground plane, which facilitates the generation of circular polarization and enables polarization diversity. The proposed antenna exhibits pattern diversity by radiating in four distinct directions, with adjacent radiation peaks orthogonally separated in the azimuthal plane. The antenna operates over a frequency range of 4.6–5.36 GHz, with a resonance frequency of 4.9 GHz and an axial ratio bandwidth (ARBW) spanning 4.89–5 GHz. The antenna demonstrates strong inter-port isolation exceeding 25 dB at the resonance frequency, ensuring robust MIMO performance. Furthermore, all key MIMO performance metrics remain within acceptable limits. The incorporation of pattern and polarization diversity with CP makes this design highly suitable for IEEE 802.11j standard WLAN (4.9–5 GHz), WLAN (5.15–5.35 GHz), and C-band satellite communication applications.