射电天文接收机四通道均衡放大模块研制

The Design of Four Channel Equalization Amplifier Module for Radio Astronomy Receiver

中频系统是射电天文接收机的重要组成部分。接收机L,S,C和K波段的左圆极化和右圆极化信号在高频仓通过下变频转换为中频信号,中频信号通过同轴电缆传送到观测室。观测室距离射电望远镜高频仓较远,因此线损较大,且不同频率的信号损耗不同,频率越高损耗越大,导致中频信号功率较小且增益平坦度随频率增加而降低。设计了四通道均衡放大模块,提高中频信号增益并补偿增益平坦度。该模块的均衡器采用集总元件和微带线相结合的方式,具有结构紧凑、易于集成、成本低的优点。测试结果表明,在6倍频带宽内,均衡量≥8 dB,均衡后功率平坦度≤3.5 dBm,回波损耗≤-15 dB,满足射电天文中频检测系统的要求。

IF system of radio astronomy receiver is an important part of the receiver. The left circular polarization and right circular polarization signals of L, S, C and K bands in the receiver become IF signals through down conversion in the high frequency bin. IF signals are transmitted to the observation chamber by coaxial cable. The observation chamber is far from the radio telescope′s high frequency chamber, so the line loss is large, and the signal loss at different frequencies is different. The higher the frequency is, the greater the loss is, resulting in the lower power of intermediate frequency signal and the decrease of gain flatness with the increase of frequency. A four-channel equalization amplifier module is designed to improve the gain of IF signal and compensate the gain flatness. The equalizer of this module adopts the combination of lumped element and microstrip line, which has the advantages of compact structure, easy integration and low cost. The test results show that the equalization amplifying module can meet the requirements of intermediate frequency system of radio astronomy receiver with equalization measure ≥8 dB, power flatness ≤3.5 dBm and return loss ≤-15 dB within 6 x frequency band width.