Gain Enhancement for Broadband Vertical Planar Printed Antenna With H-Shaped Resonator Structures

A novel broadband high gain vertical planar printed antenna is presented. The proposed antenna is composed of a bowtie-shaped electric dipole, a loop antenna that works as a magnetic dipole, a microstrip-to-coplanar stripline transition balun, and the H-shaped resonator (HSR) structures that are used for gain enhancement, all of which are printed in the same plane perpendicular to the ground. Prototypes of the HSR-loaded antenna and the unloaded one were fabricated and measured. Analyses and comparisons of the proposed antenna are made. The HSR-loaded antenna has a wide impedance bandwidth of 51.9%, ranging from 2.31 GHz to 3.93 GHz and a stable gain of about 7.4-9.7 dBi over the whole operating band. Compared with the unloaded structure, a gain increment of about 0.5-6.0 dB over the whole band is obtained. The good electrical performances make the antenna suitable for the wireless communication systems and phased arrays.