Analyzing the CPW Modes for Frequency Re-Configurability in a Wideband Cylindrical Dielectric Resonator MIMO Antenna

This article presents a novel and a low-cost coplanar waveguide (CPW)—fed dielectric resonator (DR) based frequency reconfigurable multiple input multiple output (MIMO) antenna (DR–FRMA). The CPW feed excites cylindrical dielectric resonator (CDR) for generating wideband (WB) characteristics. For reconfiguring it into a narrowband antenna (NB), a PIN diode is introduced between the center feed line and one of the CPW side planes. Analyzing the CPW modes and DR modes it is found that the higher order ${\mathrm{HEM}}_{11\delta +1}$ mode of CDR is suppressed when the image guide (IG) like CPW mode changes to the first higher order microstrip like (MSL) CPW mode for providing narrowband characteristics. The NB antenna's operational range is 3.37–3.75 GHz, whereas the WB antenna's is 3.13–6.2 GHz. Further, a prototype is fabricated and measured to validate the simulated results. The suggested MIMO antenna exhibits a peak gain of 5.9 dBi/4.2 dBi, an isolation of −16.81 dB/−16.72 dB, and an average efficiency of 91.1%/74.28% for WB/NB, respectively. Also, the radiation pattern and the antenna diversity performance characteristics make it suitable for MIMO applications.