Low Mutual Coupling of Microstrip Antenna Array Integrated with Dollar Shaped Resonator

Mutual coupling in an antenna array is caused due to the signal leakage as the conduction current through the metallic part underneath the radiating elements and the surface wave surrounding the substrate along with the radiation leakage. The influence of mutual coupling weakens the array performances like scattering parameter, antenna gain, radiation pattern, antenna efficiency etc. The mutual coupling caused by the radiation leakage can be minimized by using circuit manipulation or by introducing the microstrip resonator of optimized design between the antenna elements. A new technique has been adopted in this paper to reduce the impact of mutual coupling by introducing a simple microstrip resonator of dollar symbol between the microstrip antenna elements. Suitably designed and proper placement of resonator structure can improve the effect of mutual coupling by suppressing surface wave propagation of a particular frequency range. It has been observed that the proposed structure produces sufficient suppression of electromagnetic coupling having a reduction of more than 43 dB at the designed frequency of 5.75 GHz. An array of four radiating elements has been designed for improving the gain of the antenna.