Miniaturised asymmetric E-shaped microstrip patch antenna with folded-patch feed

A design of probe-fed compact wideband microstrip patch antenna which is configured of an asymmetric E-shaped patch, a folded-patch feed and shorting pins, is presented in this study. In this design, unequal resonance arms fed by a folded patch produce three resonances to broaden the impedance bandwidth. Shorting pins are applied to miniaturise the size of the patch. The performance of broadening the impedance bandwidth is explored by investigating the behaviour of the surface currents on the patch. The antenna presents resonance tuning ability within the impedance bandwidth by varying the length of unequal arms. The measured -10 dB impedance bandwidth of the fabricated antenna is 76.18% from 3.34 to 7.45 GHz for ultra-wideband applications. The size of this antenna is 0.379λ_L × 0.145λ_L × 0.078λ_L, where λ_L is wavelength at the lower frequency of the measured operating bandwidth in the free space. Fabrication of this antenna is less complex than similar wideband antennas with folded-patch feed. In addition, parametric studies are performed by investigating the effects of different key parameters on obtaining an optimal design of the proposed antenna design.