A Wideband Polarization-Reconfigurable Antenna Using the Combined Characteristic Modes and Common/Differential Modes

A novel method for designing wideband dual-linearly/circularly polarized (DP/CP) reconfigurable antenna, using the termed combined characteristic modes (CHMs) and common/ differential mode (CM/DM), is presented in this letter for the first time. The orthogonality and 90° phase shift between CM and DM are illustrated by the equivalent boundaries of perfect electric conductors or perfect magnetic conductors. A loop antenna is designed as an example to illustrate the proposed polarization-reconfigurable design methods, including using CHM analysis to find the desired CMs and DMs, using characteristic excitation method to design dual-port excitation for CMs, DMs, and switchable DP/CP operation by novel feed network. The prototype was fabricated and tested to validate the presented design, where the experimental results indicate that the reconfigurable bandwidth is 2.0∼3.4 GHz (51.8%) within a compact footprint of 0.46λ
₀
× 0.46λ
₀
× 0.01λ
₀
. It has the advantages of wide bandwidth, stable gain, and especially switchable DP/CP with a simple excitation strategy. The presented method with the designed antenna will become a potential candidate for present and future wireless applications.