Wideband decoupling network for antenna coupling with large group delay

This paper presents a novel wideband decoupling network for frequency-dependent antenna coupling. The network consists of directional couplers, a transmission line, and a parallel resonant circuit. The network cancels the mutual coupling by the superposition of a designed coupling that has the same magnitude and opposite phase as the original one. Further, the proposed approach accommodates the variation in the coupling magnitude and the large group delay in the coupling phase. Therefore, it is easy to apply the approach to wideband applications. The design formulas are also derived for it. With these formulas, the resultant coupling with the proposed technique is 22.9 dB smaller than the original one at 3.5% bandwidth with a large group delay.