Improving Isolation Between Closely Spaced Patch Antennas Using Interdigital Lines

This letter introduces an effective solution for improving isolation between closely spaced patch antennas. A satisfactory isolation is realized by three interdigital lines that excite an orthogonal polarization mode on the adjacent patch. A two-patch array is simulated and fabricated to verify the decoupling effectiveness of the proposed structure. The investigations of the electric field and current distributions reveal the working mechanism of the proposed structure. The experimental results show that the achieved isolation is better than 20 dB, and the maximum isolation enhancement is 24.7 dB, with a compact edge-to-edge separation of just 0.07λ0. Moreover, the proposed structure can also be applied for the decoupling of a multielement patch array.