A Novel Design of Millimeter-wave Attenuators Using Periodic Series Structures

This paper presents a novel millimeter-wave attenuator realized using a periodic series structure. The conventional attenuators are often connected by grounded via or shunt resistor stub, such as typical π or T -shaped attenuators. The disadvantage of them is the parasitic parameter produced by the grounded via or short/open stub when working at high frequency. To overcome it, a design method by only using a periodic series structure is proposed, which consists of periodic series resistors and quarter-wavelength transmission lines. The design theory is explained using an equivalent circuit model, and the equations of the theory are presented in details. A 3dB-attenuator working by 60GHz and a 5dB-attenuator working by 65GHz both based on ceramic substrate are designed, fabricated and measured. The results show high flatness of attenuation and return loss better than −15dB.