Decoupling using diamond-shaped patterned ground resonator for small MIMO antennas

摘要

A decoupling technique using a patterned ground structure for small multiple-input multiple-output (MIMO) antennas is proposed in this study. The MIMO antenna consists of two symmetrical L-shaped inverted-F antenna (IFA) elements designed to operate in the wireless-local-area-network band and installed on a compact printed-circuit board (PCB) with a size of 72.4 × 20 mm2 serving as ground. The two IFA elements have a very short separating distance of only 16.2 mm (0.13λ). To reduce strong mutual coupling, a diamond-shaped patterned ground resonator (DSPGR) with a compact size of 16.2 × 10.13 mm2 is printed on the PCB between the two IFA elements. The effect of the DSPGR on reducing mutual coupling is studied using computer simulation. The impedance bandwidth, mutual coupling, peak gain, radiation pattern and efficiency, envelope-correlation coefficient and multiplexing efficiency of the MIMO antenna are studied using simulation and measurement. Results show that the DSPGR can dramatically reduce mutual coupling between the two IFA elements to below −20 dB within the operating frequency range of 2.18–2.65 GHz (19.5%).