Remote controlled high-Q cavity filters providing center frequency and bandwidth re-allocation

A novel re-configuration approach for high-Q cavity filters is shown to provide re-allocation of center frequency and bandwidth with only two actuations drives. It relies on a side-wall cavity arrangement that allows independent movement of the cavity end-walls at both sides; i.e. all cavity end-walls at each side are associated with one remote-controlled drive unit for a synchronous adjustment. Thus, the lengths of the cavities and the electro-magnetic (EM) field strength at the coupling discontinuities can be varied to accommodate flexible center frequency and bandwidth re-allocations. This basic principle has been considered for the implementation of 2- and 5-order filters at 11.2GHz using TE
₁₁₃
dual-mode cavities. The designs have been focused to satisfy the same demands imposed on comparable fixed filters, namely the realization of responses with convenient located transmission zeros (TZ) and the same high unloaded Q for all reallocations. The special design considerations for this reconfigurable filter development are introduced. The results of the EM-analysis of the 5-order filter and the measured remote controlled hardware of the 2-order design prove the feasibility of remote controlled center frequency and bandwidth reallocation with only two actuation drives.