Highly compact microstrip patch design based on improved capacitive Minkowski fractal defected ground structure

This article proposes an effective approach for designing a highly compact patch antenna for wireless applications at 2.4 GHz. Size reduction is realized here by adding a modified Minkowski fractal defected ground structure (M-MFDGS) under the center of the radiating patch. The antenna miniaturization procedure follows a sensitivity study for the selection of appropriate DGS shape. Incorporating this highly capacitive M-MFDGS, the resonant frequency of the patch is reduced from 4.16 GHz to 2.4 GHz without any alteration in the physical size of the microstrip patch. This enables a 71% reduction in the radiating patch compared to the conventional antenna at the same operating frequency. The variation in the antenna resonance characteristics is also validated by an equivalent transmission-line model. The fabricated antenna prototype with a very low patch size of 0.15 lambda(0) x 0.13 lambda(0), has a 10-dB return loss bandwidth of 5.20%, a realized gain of 1.4 dBi, and radiation efficiency of 65% centered at 2.41 GHz. With this novel approach, the proposed miniaturized patch antenna is found to be a suitable candidate for portable wireless communications. (C) 2019 Elsevier GmbH. All rights reserved.