Compact and Broadband Uniplanar Quasi-Yagi Microstrip Antenna

This paper proposes a compact uniplanar Quasi-Yagi microstrip antenna (MSA) with broadband characteristics to achieve end-fire radiation. The proposed design has one reflector, one ground plane (also a second reflector), one driven, and one director element. The spacing between the antenna elements has been reduced by applying the concepts of microstrip antenna, thus decreasing the antenna size along the end-fire direction significantly. The lateral dimension of the proposed antenna has been reduced by using U-shaped reflectors. The reflectors and director increase the directivity of the antenna at the lower and upper-frequency bands, respectively. Along with a compact size of (
$0.52\lambda_{0}\times 0.22\lambda_{0}\times 0.009\lambda_{0}$
), the proposed antenna provides a bandwidth of 46.5% for
$\vert \mathrm{S}_{11}\vert < - 10\ \text{dB}$
. A peak gain of 6 dBi with minimal variations (∼1 dB) is also achieved over the bandwidth. The proposed compact and broadband uniplanar Quasi-Yagi MSA is a good candidate for portable direction finding and wireless applications that require end-fire radiation in the second, third, and fourth generations of wireless networks and Wi-Fi frequency bands.