Self-Decoupling Copolarized in-Band Full Duplex Dipole Antenna With Symmetrical Radiation Patterns

Existing copolarized in-band full duplex (IBFD) antennas often suffer from an asymmetrical radiation pattern. To address this issue, a simple self-decoupling method and corresponding radiation pattern improvement technology are proposed in this letter. By exciting a superposed mode produced through two higher order modes of a widened planar dipole, a specific superposed E-field pattern can be constructed, on which the TX port and RX port can be located at a strong- and a weak-field region, respectively. As a result, a self-decoupling between the two ports is realized without any extra decoupling structures. Based on the self-decoupling method, by simply optimizing the widened dipole's shape, the electric field and surface current on the antenna are therefore adjusted, and a symmetrical radiation pattern can be realized. Simulation demonstrates that the symmetry degree of the proposed antenna is greater than 0.5 dB within −60° ≤ θ ≤ 60°, which is better than existing relevant works. Experimental verification shows that the antenna achieves an impedance bandwidth of 3.38–3.8 GHz (11.7%) and a maximum in-band isolation of 36.65 dB.