Revista: IEEE Transactions on Microwave Theory and Techniques. Vol. 50. Pp. 172-177. January 2001.

Autores: Germán Torregrosa-Penalva, Gustavo López-Risueño and José I. Alonso

A new systematic approach for designing wideband tunable combline filters is presented. New results on tunable combline filter theory are proposed and explicit design formulas, to obtain the filter design parameters from specifications, are included. These design parameters are: center frequency, resonator electrical length, instantaneous bandwidth and tuning capacitance. The proposed design technique is used to construct an X-band wideband microstrip tunable filter from 8.0 GHz to 12.0 GHz with commercial GaAs FETs as tuning elements. Parasitic effects and simulation problems are also discussed.