Full-Duplex Antenna Using DGS Based BPF

In this paper, a new design for a Full-Duplex microstrip patch antenna is introduced. It consists of two closely located rectangular microstrip patch antennas, and these radiating patches give radiation bidirectionally. The isolation between the interports of the Full-Duplex antenna is obtained by using a technique called frequency space filtering and two bowtie-shaped defected ground structure (DGS) based bandpass filters (BPFs) in the ground plane beneath the microstrip feed lines from the transmitting and receiving ports of the antenna. The duplex antenna attains the isolation of $21\mathrm{~dB}$ at the transmitting frequency $f_{t}=1.9\mathrm{GHz}$ and $34\mathrm{~dB}$ at the receiving frequency $f_{r}=2.78\mathrm{GHz}$ and transmit-receive frequency spacing frequency $f_{r}=2.78$ GHz and transmit-receive frequency spacing ratio of $r=0.37$. The proposed antenna can operate well at different frequency bands, particularly between 2 and 3GHz by varying the dimensions of the DGS BPF because its resonance frequency depends on scaling the size of the structure. Furthermore, the incorporated BPFs have a reasonable degree of selectivity and sharp frequency cut-off characteristics.