A Systematic Approach for Mutual Coupling Reduction Between Microstrip Antennas Using Pixelization and Binary Optimization

This letter introduces a systematic procedure to reduce the mutual coupling (MC) between radiating elements in a microstrip array antenna. The proposed method is based on using parasitic elements between the radiating elements. The shape of the parasitic element, which impacts the MC and other radiation properties of the antenna, is determined in a systematic pattern optimization procedure based on pixelization of the area between the antennas and application of a binary optimization algorithm. A bit with binary values of 1 or 0 is assigned to each pixel, which signifies the presence or absence of copper on the pixel surface, respectively. Afterwards, during a binary particle swarm optimization algorithm, the optimal value of each bit is obtained, which results in the optimum shape of the parasitic element. In the optimization process, reducing the MC between the radiating elements is set as the main optimization objective while maintaining good antenna impedance matching and preserving of the radiation pattern. Using the proposed method, we designed a parasitic decoupling element (resonator) between two microstrip patch antennas, which were placed close to each other. The results demonstrate that adding this resonator between the two antennas fulfilled the design objectives and reduced the MC between radiating elements by 24 dB, while preserving the radiation pattern and impedance matching. The results of the simulations have been verified by fabrication and measurements.