Miniaturised microstrip patch design based on highly capacitive defected ground structure with fractal boundary for X-band microwave communications

摘要

This article proposes a new class of miniaturised microstrip patch design for wireless communications at 10 GHz. Antenna miniaturisation is achieved here by loading a highly capacitive modified Minkowski fractal (type-2) defected ground structure (MFDGS-II) exactly beneath the center of the radiating patch. The proposed methodology involves sensitivity analysis to select best DGS configuration. The resonant frequency corresponding to the patch is reduced from 16.832 GHz to 10 GHz incorporating MFDGS-II without any change in the physical size of the antenna. This enables a patch size reduction of as high as 68% and an overall volumetric reduction of 84% along with an improvement in bandwidth and efficiency of the antenna. A prototype of the proposed antenna is fabricated, and its performance parameters are measured. An equivalent transmission-line model is presented to explain the theoretical background behind the shift in the resonant frequency of the antenna. Our antenna prototype with a lower patch size of 0.20 lambda(0) x 0.15 lambda(0), exhibits an impedance bandwidth of 270 MHz, a realised gain of 3.2 dBi with radiation efficiency of 98% centered at 10 GHz. The proposed compact antenna has the potential to meet the practical requirements for portable X-band wireless sensor applications.