In-Band Full-Duplex Coradiator Antenna With High Isolation Using Differential Feed and Dual Polarization for 2.4 GHz WLAN

This letter proposes a novel dual-polarized in-band full-duplex antenna with good interport isolation for the 2.4 GHz WLAN application. The proposed antenna consists of a coradiating patch, which is excited orthogonally with differential feed using the meander slotline balun and normal feed. The meander slotline balun provides differential feed, equal and opposite driving currents, to the patch and effectively suppresses the leakage of surface currents to the other port. Similarly, the leaked in-phase surface currents from the other port generate countering fields in the balun and the interference of countering fields results in neutral coupling. The meander slotline balun, due to its characteristics, improves the interport isolation of the antenna. The proposed antenna provides a minimum of 64 dB interport isolation in the (2.4–2.5) GHz band with significantly low cross-polarization. The prototype of the proposed antenna is fabricated and tested in the anechoic chamber. The simulation and measured results of the prototype show a reasonable correlation, and the far-field measurement shows that the antenna delivers the broadside radiation in both planes with a low cross-polar of less than −35 dB at the 2.45 GHz resonant frequency. The designed meandered slotline balun offers trivial magnitude and phase imbalances of (0.04–0.06) dB and
${\pm \mathbf{{\text {2}}}^{\circ}}$
, respectively.