Compact Dual-Band Decoupling Structure for Improving Mutual Coupling of Closely Placed PIFAs

Abstract

In this letter, a dual-band isolation enhancement technique for two closely located dual-band planar inverted-F antennas (PIFAs) is proposed using a compact planar spiral line (PSL) structure. The decoupling structure has the dimensions of less than 0.15λ × 0.1λ and can be flexibly applied to various practical multiple-input multiple-output systems. By employing this structure, two PIFAs (with port distance of 0.1λ) can achieve high isolation better than 20.3 and 26.7 dB within the lower band (2.4-2.483 GHz) and higher band (5.25-5.9 GHz), respectively. Meanwhile, the decoupling mechanism and design requirement of PSL are discussed. Influences of the proposed PSL to the efficiency, gain, and radiation pattern of PIFAs were also studied. Good agreement between the simulated results and measured results is obtained.