Miniaturized reconfigurable tri‐polarization metantenna based on characteristic mode analysis with high‐aperture efficiency

This article presents a miniaturized reconfigurable tri‐polarization metantenna with compact size of 0.58 λ0× 0.58 λ0× 0.04 λ0 (λ0 is the free space wavelength referring to the antenna center frequency). Metantenna means the metasurface is directly used as the antenna radiator aperture instead of an accessory. The metantenna is formed by miniaturized windmill like units, which is evolved from square patch units based on characteristic mode analysis, and 46% size reduction is achieved. Two PIN diodes are introduced into the feeding microstrip for switching among tri‐polarization. The measured −10 dB impedance bandwidths are 24.6% (3.24–4.15 GHz) and 24.1% (3.26–4.05 GHz) for circular polarization (CP) and linear polarization (LP), respectively. The measured overlapped 3 dB axial ratio (AR) bandwidth is 15% (3.4–3.95 GHz). The measured peak gains are 5.15 dBi, 5.21 dBic, and 5.25 dBic for LP, left hand (LH) CP and right hand (RH) CP, respectively. The aperture efficiency is 77.3%, 78.5%, and 79.1% for LP, LHCP, and RHCP, respectively. The measured AR beamwidth (BW) of LHCP in XZ‐plane and YZ‐plane is 192° and 174°, respectively, the measured ARBW of RHCP in XZ‐plane and YZ‐plane is 201° and 166°, respectively. The developed metantenna has the following advantages: broadband 3 dB AR bandwidth, wide ARBW > 166°, least PIN number (tri‐polarization with 2 PIN), and high‐aperture efficiency.