Isolation Improvement Using the Field-Circuit Combined Method for In-Band Full-Duplex MIMO Antenna Arrays

Abstract

This paper proposes a field-circuit combined decoupling method for co-polarized in-band full-duplex multiple-input multiple-output (MIMO) antenna arrays. The proposed field-circuit combined method is composed of decoupling network and neutralization-based decoupling. An in-band full-duplex antenna with high isolation and low cross-polarization level is designed and extended to a 1 × 4 linear array. The decoupling network and ADS are applied for the array to alleviate the mutual coupling by rebuilding the neutralization wave paths in the circuit and field domains. Thus, low coupling (< −25 dB) among the transmitting/receiving antennas and high isolation (> 47 dB) between the transmitting and receiving antennas are achieved at 2.6 GHz, exhibiting a superior decoupling performance.