Cryogenic BTS Receiver Front End Demonstrator

A tower-mounted cryogenic BTS receiver front end demonstrator composed of HTS preselection filters followed by cryogenic LNAs has been designed, manufactured, and tested. A building block of the filters is a novel planar dual-mode structure exhibiting two controllable transmission zeros in addition to two poles. In combination with a very high unloaded Q-factor of the resonators (about 90,000 @ 60 K) this enables a new way of obtaining elliptic frequency characteristics, resulting in extreme steep filter skirts together with a very low insertion loss.