Self-Decoupled Multiantennas With Coupling Modes Identification and Suppression

In this letter, a self-decoupling method is proposed for multi antenna systems based on the identification and suppression of coupling modes. Coupling modes are first identified by characteristic mode analysis, with the coupled power due to each mode quantitatively monitored for the first time. Together with the modal weighting coefficients, the coupling modes to be suppressed are determined. Antennas are then adjusted to break the high-coupling modes without affecting the radiating modes, leading to enhanced isolations. An example involving two identical side-by-side metasurface-based patch antennas with extremely close proximity (0.014λ₀) is given. By etching slits at the proper locations of the antennas, the coupling modes have been effectively suppressed without compromising the primary radiation. As a result, the isolations between the antennas are significantly improved by more than 15 dB without additional decoupling structures. The patterns are restored as well. Measurements have been conducted on the antenna systems, showing the feasibility of the self-decoupling method.