Gain enhancement for wide bandwidth endfire antenna with <i>I</i> ‐shaped resonator (ISR) structures

Abstract

A broadband gain enhancement endfire antenna is presented. The gain enhancement is achieved by loading with an I‐shaped resonator (ISR) structure in the endfire direction. Broad bandwidth is realised by using a microstrip‐to‐coplanar balun and bowtie dipole elements, while gain enhancement is achieved by loading the ISR structure in the endfire direction. The measurements show that the ISR‐loaded antenna presents a gain of about 4–8 dB in the whole working band (4.5–9.5 GHz), which is about 2 dB more than the unloaded one. The advantages of broad bandwidth and high gain make this antenna valuable in wireless communication systems.