自激振盪式主動洩漏模天線

Abstract

本論文提出一種由HEMT差動放大器與短微帶線組合而成之自激振盪式主 動洩漏模天線.首先設計一種差動饋入的短洩漏模天線(約0.7自由空間波 長),該天線產生雙耳輻射場型,為一四埠元件(差動輸入及輸出),並可作為 主動天線中之輻射元件.其次,利用微帶洩漏模天線及回授振盪器設計出振 盪器型主動式天線.在此電路中,短微帶線扮演振盪器的回授網路暨輻射元 件.兩條高阻抗微帶線用來連結放大器與洩漏模天線回路.設計出的自激振 盪式主動洩漏模天線振盪頻率為 11.8 GHz, 且有 10.74 dBm 的輸出功 率. 最後提出利用非線性傳輸線作為電路中的相位控制元件,可使振盪頻 率擁有約 300 MHz 的可調範圍. In this thesis, a HEMT-based differential amplifier integrated with a shortmicrostrip line is present for an self-oscillating active leaky-mode antenna.First, a differential feed short leaky-mode antenna with dual-beam radiationpattern is designed. This four-port element ( differential inputs and outputs)can be used in the active antenna as a radiating element. Secondly, weemploy a microstrip leaky-mode antenna and a feedback oscillator to design anoscillator type active antenna. The short microstrip line serves as a feedback network of the oscillator as well as a radiating element. Two highimpedance microstrip lines are used for interconnecting the differentialamplifier and the leaky-mode antenna feedback loop. The self-oscillating active antenna has been developed at 11.8 GHz and 10.74 dBm output power.Finally, we present a nonlinear transmission line (NLTL) used in the circuitas a phase-controlling element to tune the oscillation frequency with tuningbandwidth about 300 MHz.