A Study Of Several Novel Microwave Passive Components And Quasi-Yagi Antenna Arrays

With the phenomenal development in the information industry, microwave passivecomponents with multiband, wideband and miniature characteristics will be found very usefulin various wireless communication systems. As the fundamental components extensively usedin microwave and millimeter-wave circuits, power dividers and microwave filters have beenadvanced tremendously. Therefore, researching on the realization of novel power dividers andfilters with high performance becomes an important topic in microwave passive componentfield. As the main part of research projects, this dissertation is mainly concerned with thedesign of various broadband power dividers and dual-band filters, as well as theimplementation of a broadband quasi-Yagi antenna array. The author’s major contributions areoutlined as follows:1. Three hook-shaped microwave filters for WLAN operations have been studied. Theresonant and coupling properties of microstrip and defected hook-shaped resonators arestudied in comparison firstly. Then, two novel compact microstrip hook-shaped resonatorfilters, one is a dual-band operation using opposite hook-shaped resonators and symmetrictapped feed structure, and the other has harmonic suppression characteristic by using twocentrosymmetric hook-shaped resonators and zero degree asymmetric feed structure, areanalyzed and designed, separately. Finally, a dual-band microwave filter using defectedhook-shaped resonator is proposed.2. Four broadband power dividers using DGS have been studied. Firstly, by using astepped impedance defected split-ring resonator (SI-DSRR) and a pair of opposite F-shapedDGS, a two-way and a three-way equal UWB Wilkinson power divider with band-notchedcharacteristics are presented. Since the SI-DSRR and F-DGS are both λ/2resonators, it isconvenient to adjust the resonance frequency of the notched band mainly by changing theirdimensions. Secondly, using a novel DGS and a “工” shaped DGS，a two-way broadband4:1unequal Wilkinson power divider and a three way4:1:1unequal power divider areimplemented. By using the proposed DGS, microstrip lines can be realized with very highimpedance of over150, and avoiding the fabrication problems caused by the very thinconductor microstrip width.3. Four broadband power dividers using microstrip-slotline have been studied. Firstly,with T-shaped microstrip feed lines and semicircular branches, novel two-way and four-wayminiature power dividers utilizing coupling via a multilayer microstrip-slot have beenanalyzed to exhibit broadband characteristics. Then, two uniplanar designs of three-waypower dividers using modified broadband slot-coupling configurations are presented. The gradual slot lines and semicircular/semiellipse slot short stubs are used to improve theimpedance matching. The measured results of the proposed three-way power dividers exhibitgood performance on insertion loss and amplitude balance.4. A quasi-Yagi antenna linear array has been studied. Firstly, a printed quasi-Yagiantenna with bend arms and an impedance transformer is proposed for a wide operatingfrequency band. Then, the differential evolution method is used to obtain the optimal powerdistribution for the low sidelobe array. Finally, as the feeding network of the array, aneight-way broadband unequal power divider is designed. Moreover, an8-element quasi-Yagiantenna linear array prototype is constructed to validate the feasibility and efficiency of thedesign.