Understanding antenna mutual coupling through characteristic modes

In this contribution, characteristic mode analysis is adopted to analyze antenna coupling in a systematic way. The mutual admittance is separated into several fundamental modes, and the contribution of each mode is evaluated through the modal mutual admittance (MMA). Some higher order modes, which contribute little to the in-band radiation but much to the out-of-band coupling, are discriminated and suppressed using lumped loads. For monopole-type antennas deployed on platform, the weighted engencharge distribution helps determining the suitable deployment positions for a smaller mutual coupling.