A Wideband Printed Quadruple-Element Antenna With Integrated Balun

A printed ultrawideband (UWB) unidirectional quadruple element antenna is presented. The antenna is composed of four radiating elements with corrugated boundaries and a microstrip-to-double-sided parallel-strip line transition. The antenna size is
$0.285\lambda_{\rm L}\times 0.285\lambda_{\rm L}\times 0.174\lambda_{\rm L}$
at the lower operating frequency. Experimental results reveal that it can achieve an impedance bandwidth of 83.7% for
${\rm VSWR}<2$
and a stable unidirectional radiation pattern with measured gain around 6.7 dB. Simulated and measured results are given, and they agree well with each other.