Printed Direct-Antenna with Skirted Active Dipole

In order to improve the direct-antenna's operating bandwidth, a printed direct-antenna adopting skirted dipole antenna as active dipole is proposed. The antenna is a single-face PCB structure and printed on the FR-4 substrate with 1.5mm thickness. The skirted dipole antenna is fed by coplanar waveguide, both sides of which are printed metal straps, used as the director and reflector respectively. The structural parameters are optimized by CST MICROWAVE STUDIO® and the prototype has been fabricated according to the simulated results and measured in microwave anechoic chamber. The experimental results indicate that the operating bandwidth is from 2.60GHz to 3.95GHz with reflection coefficient less than -10dB, and the in-band gain is higher than 4.5dBi, both of which match the simulated results well. Moreover, the compact size of the antenna is just 49mm×45mm (0.53λ0×0.49λ0). These advantages can promise the proposed antenna to be widely applied in WiMAX systems.