高平坦度大功率连续可变衰减器

High Power and Good Attenuation Flatness Continuously Variable Attenuator

介绍了一种连续可变衰减器,采用带状线传输线结构,以导热性能优异的氧化铍陶瓷为基材,提高传热效率,增大产品的功率容量。在氧化铍陶瓷上加载厚膜电阻,利用厚膜电阻对电场的极化吸收实现对微波能量的衰减,通过改变厚膜电阻相对于中心导体的位置来实现衰减量的连续可变。利用厚膜电阻优异的衰减量平坦度特性来实现产品的高平坦度要求。利用HFSS有限元分析软件辅助设计,提高工作效率,降低调试难度。产品外形尺寸：120mm×100mm×70mm,产品实测性能：在1.2～1.4GHz范围内,插入损耗≤0.4dB,电压驻波比≤1.45,衰减量：0.4~7dB,衰减量平坦度：±0.1dB（≤4dB）、±0.2dB（≤7dB）,功率容量：200W（平均功率）。产品实测性能与HFSS软件的仿真结果基本吻合。

This article mainly introduces a type of stripline continuously variable attenuator using BeO ceramics as its base material.The BeO ceramics has good thermal conductivity,thus the power capacity of the attenuator is enhanced.By loading thick-film resistor on the BeO ceramics,the attenuation of microwave power is realized through polarization absorption of thick-film resistor to electric field.By changing the position of thick-film resistor relative to centre conductor continuous variability of attenuation can be achieved.Excellent attenuation flatness of thick-film resistor can meet the requirements of high attenuation flatness of the device.HFSS finite element analysis software was used to improve the design efficiency and reduce the tuning difficulties.Attenuator with dimension of 120mm×100mm×70mm was designed,featuring insertion insert loss： ≤0.4dB,VSWR： ≤1.45,attenuation：0.4-7dB,attenuation flatness： ±0.1dB（attenuation≤4dB） and ±0.2dB（attenuation≤7dB）,power capacity： 200W（average） in frequency range of 1.2-1.4GHz..The test performance results are in accordance with the HFSS simulations.