In-Band Full-Duplex Antenna Using Orthogonal U-shaped Slot Antenna

In this paper, a new design is proposed for the in-band full-duplex antenna for 5G communication systems. The proposed two-port in-band full-duplex antenna consists of orthogonally arranged two U-shaped slot sections which are fed by coupled microstrip lines. The microstrip-coupled coplanar waveguide (CPW) is used at both ports to excite the U-shaped stepped-slot sections in the CPW odd mode. The surface currents from the active port interact with the other port in CPW even mode and result in neutral electromagnetic coupling from the stepped slot to the microstrip line. The interport isolation is achieved by CPW odd mode excitation of the individual stepped slot and it is further improved by the orthogonal arrangement of stepped slots. The proposed antenna has a minimum of 39 dB of interport isolation over the entire operational band and a maximum of 47 dB at 3.52 GHz. The -10 dB impedance bandwidth of both ports is 370 MHz and resonates in the 5G band of (3.32-3.69) GHz. The design provides the broadside radiation pattern with cross-polar content of less than -20 dB. The gain of the antenna for port1 and port2 is 3.8 dBi and 4.5 dBi, respectively at 3.52 GHz.