Reduction of mutual coupling between patch antennas using defected ground structure in L‐ and S‐bands

Mutual coupling (MC) is a common phenomenon in array antennas, which severely reduces antenna performance. Therefore, reducing MC is an important direction in array antennas. This article presents a novel defected ground structure (DGS) suppressing the MC between L‐ and S‐band microstrip patches. The antenna operates in two frequency bands with both relative bandwidths of approximately 10%. To reduce the overall size, the antennas of the two bands are designed together, using the same ground, reflective cavity, and dielectric substrates. By introducing six DGSs in the middle of the ground, the surface currents of the two frequency bands are cutoff, thus reducing the MC. A prototype is fabricated and measured. From the measured results, the isolation of more than 26.18 dB can be achieved in the L‐band from 1.6 to 1.8 GHz, and the isolation of 12.3 dB can be achieved in the S‐band from 2.05 to 2.25 GHz with the adoption of the DGS. The impedance bandwidth with return loss greater than 15 dB is 11.76% and 9.3% in the L‐ and S‐bands, respectively, which provides valuable reference for the design of other dual‐band antennas.

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