Dual-Band Dual-Polarized Slotted-Patch Antenna For In-Band Full-Duplex Applications

This letter presents a dual-band dual-polarized slotted-patch antenna with high isolation and high gain for in-band full-duplex (IBFD) applications. The antenna consists of a double differential-feed 45^\circ-rotated square patch with four capacitively-coupled \Gamma-probes. The proposed design utilizes the TM 10 resonant mode of the patch for the lower resonance, whereas four trapezoidal slots are symmetrically etched on the patch to generate the upper resonance. By examining the feeding locations, the four slots can be excited simultaneously, yielding a high-gain radiation at the upper resonance. A design operating at 2.45/5.25 GHz has been optimized with two dual-band rat-race couplers employed to realize the double differential-fed scheme. The fabricated prototype with a profile of 0.06\lambda _{\rm{2.45-GHz}} yields a measured 10-dB return loss bandwidth of 2.40-2.52 GHz and 5.09-5.41 GHz, an isolation of \ge 44 dB and 41 dB, a gain of 8.5 dBi and 9.2 dBi, and a cross-polarization level of \le -32 dB and -22 dB for the lower and upper bands, respectively.