Compact high isolation microstrip antenna based on mode cancellation
In order to reduce electromagnetic coupling between compact microstrip antennas,a simple low-profile decoupling structure was proposed.This proposed structure consisted of a microstrip-short-circuited probe structure between two antennas and a defected ground structure.The working principle of the decoupling structure was elaborated based on the mode cancellation method using in-phase and out-of-phase modes.Furthermore,the coupling mode of the electric field between adjacent antennas in the E-plane and the influence of the decoupling structure on the electric field distribution were analyzed.The effectiveness of the proposed scheme was validated under the condition that the spacing between the adjacent edges of the antennas was 0.054λ(λ is the wavelength in free space at the center frequency).Test results demonstrate that an isolation improvement exceeding 10 dB within the matching bandwidth of 3.03-3.28 GHz was achieved with the designed antennas.At the center frequency,the isolation achieves 47.28 dB.The envelope correlation coefficient is lower than 0.025.This decoupling structure is simple and effective with low profile.Furthermore,it occupies small space and has strong coupling suppression capability.It not only increases the antenna operating bandwidth but also exhibits stable radiation performance.
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