Synthesis of Dual-band Filter with Improved Functionality Based on Dual-mode Resonator

The problem of improving dual-band filter functionality based on dual-mode resonator is solved. Stepped-impedance transmission line segments (SILS) with the required arrangement of resonant frequencies are synthesized to solve this problem. These SILS have the minimum value of parameter m = Z
0
max/Z
0
min, which is defined as the optimal criterion. The method of parametric synthesis was used for optimization. Two ends of the SILS are short-circuited. A short-circuited stub of short length is connected to the middle of the synthesized SILS. As result, a new dual-mode dual-band filter with enhanced functionality is obtained. This filter allows us to change the relative position of two passbands over a wide range. This filter can also significantly increase the operating frequencies. The data of measurements of the microstrip filter prototype are presented.