Revista: IEEE Transactions on Microwave Theory and Techniques. Vol. 53. Pp. 191-199. January 2005.

Autores: Manuel Sánchez-Renedo, Roberto Gómez-García, José I. Alonso and César Briso-Rodríguez

A new combline filter structure with a continuous tunability for both the center frequency and bandwidth is presented
in this paper. The passband-width tunability is achieved by placing variable coupling reducers between the filter resonators. The coupling reducers, operating as bandwidth control subnetworks, are designed as detuned resonators made up of a line segment ending in a variable capacitor. The proposed filter structure is experimentally validated with the design, construction in suspended stripline technology, and characterization of a low-cost filter prototype for terrestrial digital video broadcasting receivers operating in the UHF band (470–862 MHz). Other relevant factors, such as the intermodulation distortion produced by the varactors used to control the bandwidth electronically or the power-handling performance of the constructed filter, are also discussed. The reconfigurable filter module described in this paper
is very suitable for the design of ?exible multifunction receiver subsystems simultaneously supporting signals with a different bandwidth.