Decoupling Method for Two Planar Inverted-F Antennas using Characteristic Mode Analysis

Abstract

This study proposes a decoupling method for Two Planar Inverted-F Antennas (PIFAs), which are mounted on a ground plane, using Characteristic Mode Analysis. According to the simulation results of Modal Weighting Coefficient, two types of mode (in-phase mode and anti-phase mode) are observed and total inner product of modes is calculated. When the total inner product value is close to zero, the excited current from the two ports is orthogonal to each other, resulting in a reduction of the mutual coupling. Based on this, we use four L-shaped elements, which are placed on several certain positions on ground plane, to excite a dominant mode in order to adjust the total inner product value to be closer to zero. As a result, the total inner product can be adjusted from −0.43 to −0.3 and the mutual coupling can be reduced from −6.6 dB to −10.2 dB.