Conventional broadband couplers use multi-sectioning techniques and consist of multiple coupled lines. In this study, in contrast to traditional methods, one pair of coupled lines is used to design multi-octave broadband couplers. In the proposed microstrip couplers, the coupled lines are weakly coupled and are of one-eighth wavelength at the highest operating frequency. The weakly coupled lines exhibit a linear coupling response with a slope of 6 dB/octave. To compensate the coupling response, one-pole low-pass networks with a slope of −6 dB/octave are cascaded with the microstrip coupled lines. To validate the design concept, two broadband microstrip couplers for the frequency range of 30–500 MHz and 1–3 GHz have been designed and fabricated. The couplers exhibit a coupling of 52 and 39 dB, respectively. The broadband couplers provide a ripple of 0.5 dB in the coupling response. The proposed weakly coupled couplers are adequate for high-power measurements. The weak coupling permits lumped-element surface mount devices to be used as the compensating network. The multi-octave couplers are realised in small areas.

中文翻译：

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超宽带微带定向耦合器

常规的宽带耦合器使用多段技术，并且由多条耦合线组成。在这项研究中，与传统方法相反，一对耦合线用于设计多倍频程宽带耦合器。在提出的微带耦合器中，耦合线是弱耦合的，并且在最高工作频率下具有八分之一的波长。弱耦合线表现出线性耦合响应，斜率为6 dB /倍频程。为了补偿耦合响应，将具有-6 dB /倍频程斜率的单极低通网络与微带耦合线级联。为了验证设计概念，设计并制造了两个宽带微带耦合器，其频率范围为30–500 MHz和1-3 GHz。耦合器的耦合度分别为52 dB和39 dB。宽带耦合器在耦合响应中提供0.5 dB的纹波。所提出的弱耦合耦合器足以进行大功率测量。弱耦合允许将集总元件表面安装设备用作补偿网络。多倍频程耦合器在较小的区域内实现。