Theoretical and Experimental Analysis of Microwave Dielectric Resonators Active Filters

The purpose of this paper is to present theoretical and experimental results of microwave active filters using dielectric resonators (D.R.) Generally speaking, these active filters are obtained by connecting to the classical passive D.R. filters coupled to microstrip lines, an active loop composed of an amplifier and a phase shifter. The advantages of these circuits are to improve loaded Q of the D.R. and the filtering selectivity, to compensate dissipative losses and to permit an electrical tuning of resonant frequency and bandwidth [1], [2], [3]. An improved three poles D.R. active filter model has been realized including microwave passive and active circuits and tuning D.C. bloc (figure 1). No losses with a 24 MHz 3 dB bandwidth was easily obtained.