基于双面平行带线的小型化谐波抑制混合环

Miniaturized Harmonic Suppression Rat-race Coupler Based on Double-sided Parallel Stripline

提出一种基于双面平行带线(Double-sided parallel strip line,DSPSL)的小型化谐波抑制混合环。采用一条高阻抗线并联谐振枝节代替传统的λ/4传输线,并用DSPSL反相单元代替λ/2传输线,以实现减小混合环尺寸。通过并联谐振枝节引入带外传输零点,使谐波抑制到第七次谐波。采用此方法设计了一个中心频率为1 GHz的混合环,测试结果表明,设计的混合环能够改善传统混合环性能,使相对带宽达到90.2%,0~7 GHz的频带内隔离均大于20 dB,并保持在5.3 GHz附近插入损耗大于40 dB,实现良好的谐波抑制水平,并且该混合环尺寸缩小为传统混合环的18.6%。

A miniaturized harmonic suppression rat-race coupler based on double-sided parallel stripline(DSPSL)was proposed.A high impedance line parallel resonant branch was used to replace the traditionalλ/4 transmission line,and theλ/2 transmission line was replaced by DSPSL inverting unit to reduce the size of the rat-race coupler.By introducing out of band transmission zero through parallel resonant branches,the harmonic was suppressed to the seventh harmonic.Using this method,a rat-race coupler with a center frequency of 1 GHz was designed.The test results show that the designed rat-race coupler can improve the performance of the traditional rat-race coupler,make the relative bandwidth reach 90.2%,the isolation in the frequency band of 0-7 GHz is greater than 20 dB,and keep the insertion attenuation near 5.3 GHz greater than 40 dB,so as to achieve a good harmonic suppression level.In addition,the size of the rat-race coupler is reduced to 18.6%of that of the traditional rat-race coupler.