A Simple All-in-One Shared-Aperture Decoupling Network (SADN) for Coupling Management in a Tri-Band Differentially-Fed Antenna (DFA) Array

A shared-aperture decoupling network (SADN) is developed to mitigate multiple types of mutual couplings within a tri-band antenna array, comprising two high-band (HB), two middle-band (MB) and two low-band (LB) differentially-fed antennas (DFAs). The SADN is an all-in-one decoupling solution but features remarkable simplicity and compact size. A decoupled tri-band DFA array operating in the LB (9.8-10.2 GHz, 3.5%), MB(18.1-19.2 GHz, 6.1%), and HB (25.5-28.9 GHz, 12.5%) has been designed, fabricated, and experimentally validated. The results demonstrate impressive in-band isolation levels of 28 dB, 27 dB, and a remarkable 52 dB at the center frequencies of LB, MB, and HB. Additionally, cross-band coupling is also effectively suppressed. All isolations between any two ports of the six antennas across the three bands are maintained larger than 20 dB. This superior decoupling performance is achieved through the novel symmetrical residual current cancellation (SRCC) principle, specifically designed for and uniquely applicable to DFAs.