Compact Co-Linearly Polarized Full-Duplex Patch Antenna with Lumped Capacitors and Single-Layered Substrate

A method of blocking coupling current between two ports is offered with high isolation for co-linearly polarized full-duplex patch antenna. Here, such a bi-port patch antenna can be treated as two side-by-side PIF As with zero-distance. By loading a composite decoupling structure along the center of the patch, good isolation is realized within a single-layered substrate and compact size. The proposed decoupling structure consists of lumped capacitors and distributed shorting pins, which essentially behaves as a LC filter. When the LC filter resonates, strong radiation current is mainly centered on half a patch, thus leading to high isolation between the two PIFAs. Simulated results illustrate that the bi-port patch antenna realizes a maximum port isolation, which is superior to 30 dB when it operates at the central frequency of 2.38 GHz within a tight dimension of 0.25 $\lambda_{0}\times 0.25 \lambda_0 \times 0.03$ λ0. Owing to these virtues of tight dimension, easy fabrication, and low cost, the proposed antenna promises huge potential usage in in-band full-duplex applications, mobile termi-nals, and other volume-limited communication systems.