根据微带耦合线的准TEM模参数 ,推导出相同耦合线Marchand巴伦须满足的导纳方程 ,讨论了改善巴伦性能的方法———电容补偿法。ADS仿真结果表明 :采用最佳条件选取的耦合线 ,巴伦的反射系数接近最小 ,传递系数接近最大 ;采取电容补偿后 ,可进一步改善巴伦的性能。最后给出宽边耦合线巴伦的实验结果。结果表明 :可用上述导纳方程设计巴伦耦合线的参数。

An admittance equation which Marchand balun with equal coupled-lines must satisfy is derived, basing on quasi-TEM mode parameters of microstrip coupled-line. Furthermore a technique -adding lumped capacitances at the ends of the coupled line-to improve directivity of microstrip couplers is discussed. Simulations of ADS shows: using coupled-line demension determined by admittance equation , reflection coefficient approaches the lowest value while forward transmission coefficient approaches the largest, and by adding lumped capacitances at the ends of the coupled line can improve its characteristics. Finally experimental results of using broadside coupled-line are given, which show the admittance equation can be used in design of balun. [

TN957