Ultrathin Dual-Band Circularly Polarized Antenna
Mingzhe Hu, Yue Li, Yongjian Zhang, Pengfei Wu, Hanyang Wang
Abstract
This letter presents a dual-band circularly polarized microstrip antenna with an ultrathin substrate made of liquid crystal polymer (LCP). The proposed antenna consists of a gridded patch and a round of via fence for dual-band radiation and size miniaturization. Compared with the previous designs, the proposed antenna has two improvements in structures with merits: first, a parasitic patch is added below the gridded patch to tune the ratio of dual-band frequencies; second, a stacked feeding network with dual orthogonal L-shaped probes is designed for profile reduction, also providing the feasibility of differential feed and dual-linear polarization. Based on the codesign of the gridded patch, the parasitic patch, and the stacked feeding network, all layers of the antenna are clamped into a flexible board with an ultrathin thickness of 0.6 mm (0.013λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at 6.5 GHz) and taped out with the flexible LCP process. The measured results show the bandwidths of total efficiency over 25% are 6.25–6.74 GHz and 7.92–8.17 GHz with circular polarization, proving to be a feasible solution for flexible antennas in space-limited mobile handsets.