A planar Single-layer Colinearly Polarized Antenna With High Isolation

In this letter, a planar single-layer collinear polarized antenna with extremely high inter-port isolation is presented for in-band full duplex application. The proposed antenna is designed on two-element patch, where a etched slot are loaded in the middle line, which further enhance the cross-polarization. Additionally, two stubs are introduced to both edges of the patch, which lead in transmission zero. The structure experimentally exhibits a bandwidth $(\lt -10)$ of $7.5 \%(28.08-30.26 GHz)$ with the isolation of 18dB, peak isolation of 73 dB at 29.2 GHz. In addition, the realized gain is 5.3dBi, and the cross-polarization is less than -17dB.