Design of a Simple, Compact and Ultra-Wideband Quasi-Yagi Antenna with Single fed Monopole

This paper presents the design of a compact and ultra-wideband quasi-Yagi antenna (QYA) with a single fed monopole. The proposed antenna has a much simpler structure than other QYA, facilitating easy integration with other monolithic circuitry and mass production. Two wide strip directors are placed close to the driven element to excite additional resonances at higher frequencies and obtain wider impedance bandwidth. To improve the impedance matching, width of MS feed-line is tapered towards the driven monopole feed point. A prototype of the designed antenna is fabricated and measured. The measured results are in good agreement with the simulated. The prototype has a compact size of 57mmx66mm, - 10 dB impedance bandwidth of 117.3% from 1.53 GHz to 5.86 GHz, and a peak gain of 6.4 dBi. Within the operating band, the antenna has stable end-fire radiation patterns, the front-to-back ratio of over 8 dB, and cross-polarization levels below -25 dB.