Transmit-receive (T/R) isolation enhancement with an indented antenna array

This paper presents a T/R isolation enhancement technique that takes advantage of the different phase delay characteristics of the T/R paths in an indented antenna array. The purpose is to enhance the T/R isolation from what is offered by circulators as well as to overcome the antenna reflection power without limiting the choices of antenna polarizations and radiation patterns. The essential idea of indented array is to offset the antenna element away from the broadside of the array aperture so that the leakage signal and reflection from each individual antenna is cancelled when combined. An eight-element antenna array is designed and co-simulated with feeding network in ADS. The simulation results show 18dB average isolation improvement and 20dB return loss improvement of the eight-element antenna array.