At present,several methods for millimeter frequency band suppressionare known [I]. The essential defects of these methods lie, as we think,in complicated construction, high attenuation level in key-in region,unprofitable correlation between controlling sizes and other element'ssizes. This makes impossible to regulate gain frequency characteristic.Moreover, respective devices have unprofitable weight-size parameters.Discribing filter has two important advantages, namely higher attenua- tion level and a simple construction as oompierd with previosly knownone. This has been achived by using a combinaton of two transmissionlines: an insulated image duide (IIG) and microstrip.
S. A. Pogarsky,
"Rejection filter", Proc. SPIE 2104, 18th International Conference on Infrared and Millimeter Waves, 210448 (30 August 1993); doi: 10.1117/12.2298584; https://doi.org/10.1117/12.2298584