变容管电调微波带通滤波器

本文叙述采用梳状线结构的变容管电调微波带通滤波器的设计理论和方法。推导出梳状线带通滤波器的输入、输出耦合网络的参数条件,以补偿带通滤波器的谐振器之间电磁耦合随不同调谐频率的变化;并给出使带通滤波器的绝对带宽或通带回波损耗在调谐频率范围内变化最小时,梳状线谐振器的电长度应满足的相应条件,由此来保证电调带通滤波器在较宽的调谐频率范围内具有较高的通带回波损耗,且保持带通滤波器的响应形状和绝对带宽基本不变。此外,还讨论了由电调变容管的Q值引起的带通滤波器的通带有功损耗问题。文中给出了具体的设计公式。最后,给出了一个L波段变容管电调带通滤波器的研制实例和测试结果。

Varactor tuned microwave bandpass filters

This paper explicates the design procedures for varactor tuned combline microwave bandpass filters. A tunable combline bandpass filter is described in which the internal electro-magnetic coupling frequency dependence between resonators is compensated to a large degree by correct design of the terminating transformer elements. Using this filter, octave tuning can be achieved while rataining high passband return loss. In addition, this filter possesses the important property of maintaining approxi- mately constant absolute passband bandwidth independent of tuned frequency. Explicit design formulas are presented for this filter. The passband dissipation loss of a bandpass filter produced by the Q factor of the electronically tunable varactors is also discussed in this paper. Finally, the design and experimental performance of a L-band varactor tuned combline bandpass filter are presented.