提出一种具有谐波抑制的小型化混合环耦合器.采用T型结构代替7λ6混合环中的每一段λ6传输线,以显著减小混合环的尺寸;并且通过T型结构中的并联开路枝节引入带外传输零点,实现针对三次谐波的抑制作用.为验证理论的正确性,设计了一个中心工作频率为1 GHz的小型化混合环,并给出电磁仿真和实物测试结果.测试结果表明,所设计的混合环在保持3 dB耦合器工作特性的同时,在三次谐波附近插入衰减大于30 dB,实现了良好的谐波抑制功能.此外,该混合环的尺寸仅为传统混合环耦合器的34.2%,具有广阔的应用前景.%A miniaturized rat-race coupler with harmonic suppression function is proposed,in which the T-type structure re-places each λ 6 transmission line in 7λ 6 rat-race loop to reduce the dimension of the rat-race loop,and the out-of-band trans-mission zero is introduced through the parallel open-circuit stub in T-type structure to suppress the third harmonic. In order to verify the validity of the theory,a miniaturized rat-race loop is designed,whose central working frequency is 1 GHz. The results of material object test and electromagnetic simulation are given. The test results show that the rat-race loop has perfect harmonic suppression function,and its insertion attenuation near the third harmonic is higher than 30 dB while the working characteristic of the coupler maintains at 3 dB. The dimension of the proposed rat-race coupler is 34.2% of the traditional rat-race coupler. The coupler has broad application prospect.
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