부산대학교 도서관

This work presents a novel and highly compact broadband Yagi antenna structure in multilayer configuration for Ku band applications. The antenna is formed by stacking two identical Yagi elements which are fed in-phase with a single strip-based transmission line. Metalized vias has been used to connect the ground planes and to launch the signal in the driver element of both Yagi elements. The design has multiple advantages of providing large gain, large impedance bandwidth, high front-to-back ratio along with low radiation leakage. The unique broadside coupling introduced in this topology causes constructive interference of near fields in the H-plane thus causing wider HPBW. Detailed optimization processes along with physical insight have been provided for a better understanding of the working principle. The design has been extended into a $1 \times 4$ antenna array formation in the E-plane to enhance the boresight gain. The array thus formed offers a fractional bandwidth of 26.6% over the frequency range from 16.51 GHz to 21 GHz. It produces a gain of 11.83 dBi with a front-to-back ratio of 33.2 dB. The HPBW in the H-plane is measured to be 94.7° which allows this antenna system to be used in cellular communication, scanning, and surveillance system.