Compact Co-Horizontally Polarized Full-Duplex Antenna With Omnidirectional Patterns

This letter presents a compact co-horizontally polarized (HP) in-band full-duplex (IBFD) antenna with omni-directional patterns. The Tx antenna is a variant turnstile antenna with four 90 degrees progressively phased T-shaped monopoles, whereas the Rx antenna is an in-phase loop antenna with four symmetrically excited dipoles. The polarizations and radiation patterns of both antennas are horizontally polarized and omnidirectional patterns in the azimuth plane. Nevertheless, a high measured isolation of more than 37 dB across the desired band is achieved with an orthogonal spatial phase diversity approach. To the best of our knowledge, this is the first time two co-HP omni-directional antennas are integrated with a high isolation for the IBFD communication. The proposed antenna has the potential to double the spectral efficiency of wireless communication systems and to combat the polarization variations in the rich multipath environments.