A Frequency and Pattern Reconfigurable Dielectric Resonator based 2-Port MIMO Antenna Array with Circular Polarization

In this work, a frequency-reconfigurable dielectric resonator-based 2-port multiple input multiple output (MIMO) antenna array with switchable patterns is designed, fed by sequentially arranged quarter-wave sections. The sequentially rotated (SR) feed excites each radiator element with maximum power and reduced input impedance. The antenna elements generate the fundamental HEM<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11δ</inf> modes at different phase angles. The 2-port MIMO antenna array's physical size has been optimized to measure 92x184x1.6 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>, achieving a 10dB bandwidth spanning 1.14 GHz (5.23 GHz to 6.37 GHz) and 230 MHz (6.65 GHz to 6.88 GHz), when all diodes are in ON state. It demonstrates dual circular polarization (CP) capabilities, showing axial ratio values below 3dB standard across two frequency ranges: 5.48-5.54 GHz and 6.27-6.30 GHz. The proposed MIMO antenna array shows multiple switchable patterns for various diode states and isolation below -27dB is achieved within the whole band. The resonant frequency tuning is achieved from ~5.4 GHz to 7.2 GHz. The MIMO performance parameters are well within the specified standard limit in the whole operating band showing good MIMO behavior. This optimized design makes the antenna array particularly well-suited for C-band microwave system implementations.