Three-Port Dual-Band Dual-Polarized Curved-Patch Antenna using Characteristic Mode Analysis

A dual-band curved-patch antenna with circular and linear polarizations in different bands is proposed. Revealed by characteristic mode analysis (CMA), the bending of the patch creates anisotropy that leads to separated resonant frequencies of degenerated modes to different levels for different order of modes. The understanding gained from the CMA results is utilized to achieve circular-polarized (CP) radiation at 1.88 GHz whilst dual-linearly-polarized radiation at 5.2 GHz, where the former utilizes the separated TM
10
and TM
01
modes while the latter unseparated TM
12
and TM
21
modes. The proposed antenna achieves a CP bandwidth of 4.2% for 3-dB axial ratio < 3 dB, a CP impedance bandwidth of 33.5% (1.54–2.17 GHz) and linear-polarized impedance bandwidths of 23.4% (4.78−6 GHz) and 22.2% (4.5–5.65 GHz), respectively.