Date: Monday December 1 2008, 14:00-15:00
Venue: EM233
Name: Dr Savvas Kosmopoulos
Filters using helical resonators topologies for radio frequency applications are a well known technology for RF Applications from 10 MHz up-to-to 1.5 GHz. The produce typical Q's from 200 to 5000. Currently such devices are being used as high Q bandpass filters, band rejection filters, reference cavities, tuning elements for oscillators, front end filters for receivers, and for many other applications where high Q is paramount and large size prohibitive. Disadvantages of using conventional helical resonators in the front end filter of a radio receiver is that in order to obtain satisfactory image frequency rejection many conventional helical resonators are needed, involving significant costs. Further disadvantage of using conventional helical resonators is that the amount of coupling is controlled by the size and location of the openings in the partitions which must be accurately machined, again involving significant costs. It is the object of this presentation to illustrated how to overcome the above mentioned disadvantages. To do so, various filter topologies, based on the use of helical resonators, are simulated by means of HFSS. Inderdigitally allocated helical-resonators, indicating pseudo-elliptic transfer function have been compared to input-/output-port poles extrapolation configuration, leading into the final most effective (optimized) space qualified design of very complex BPFs structures, where the use of Rexolite 1422 is also involved for multipaction prevention reasons.