一种新型宽频率比的双频环形耦合器

A novel dual-band rat-race coupler with wide-range frequency ratio

针对传统双频环形耦合器频率比范围窄的问题,通过在传统T型双频四分之一波长阻抗变换器并联短路枝节。增加了设计自由度,减小了物理实现阻抗范围的限制,从而实现了宽频率比范围(1.5~4.9)。为了验证该方法的可行性,运用该结构设计了一款新型双频环形耦合器,在低频和高频处的带宽分别达到90MHz和120MHz。并将并联短路枝节折叠进耦合器内部空间,实现了更加紧凑的结构,尺寸约为(0.147λL×0.294λL)。

As the conventional rat-race coupler is of narrow operation frequency ratio,through the traditional T dual-band 1/4 wavelength impedance converter shunt short-circuit stub. It increased the design degrees of freedom,reduced the physical implementataion impedance range limit,so as realized the wide frequency range（ 1. 5 to 4. 9）. Moreover,a new dual-band rat-race coupler is designed with this structure to verify the proposed design method,attaining 90 MHz and 120 MHz respectively at low frequency and high frequency bandwidth,and the short-circuit in parallel side fold into the internal space of the coupler. Meanwhile,it comes into being a more compact structure with new size（ about 0. 147λL×0. 294λL）.