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引言:试制了一个微波晶体管放大器,要求其通带为±20mc,但放大器是宽带的,通带在150mc以上,为抑制镜频噪声,在晶放后加进一个予选器,对镜频进行抑制。试制过一种耦合微带线带通滤波器,这个滤波器的工作没做完,但发现其带内损耗较大,约1～2db。后来又做了一个带阻滤波器,其损耗较小,在1db以下。估计带通滤波器损耗大的原因有两个、一是工艺上的,例如微带线铬底的厚度太厚或微带线厚度太簿等等,二是微带线Q值较低,带通滤波器在通带内,耦合线处于谐振状态,损耗较大。而
Introduction: trial of a microwave transistor amplifier, requiring the passband of ± 20mc, but the amplifier is wideband, the passband above 150mc, in order to suppress the image noise, adding a pre-crystallizer, the mirror frequency inhibition. Trial production of a coupled microstrip line bandpass filter, the filter did not finish the work, but found that the band loss larger, about 1 ~ 2db. Later made a band-stop filter, the loss is small, below 1db. Estimated bandpass filter loss for two reasons, one is the process, such as the thickness of the microstrip line chrome is too thick or the thickness of the microstrip line is too thin, etc. Second, the microstrip line Q value is low, with the band Pass filter in the passband, the coupling line in the resonant state, loss larger. and