A Broadband Attenuator Using Dual-Branch Resistors and Microstrip-Line-Loaded Slotline Structure With Improved Attenuation Slope

This letter presents a new method for broadband attenuator design, which uses dual-branch resistors and microstrip-line-loaded slotline structure. Resistors are loaded on slotline to achieve attenuation property, and dual-branch configuration and implantable microstrip line in each branch are proposed to improve attenuation slope within broadband when the attenuation amount becomes large. To validate the proposed design method, an 11-stage attenuator is designed and measured, which has a minimum insertion loss of 1.92 dB, a dynamic attenuation range of 20 dB, and a return loss of better than 8.5 dB, within the bandwidth of 2–5 GHz. Moreover, the effect of parasitic inductance in used resistors is also investigated to clarify the attenuation fluctuation of the measured attenuator.