Novel Compact Microstrip Dual-Mode Filters with Two Controllable Transmission Zeros

Novel compact pentagonal dual-mode filters by short-loaded are presented. The field patterns of this type of resonators are investigated using full-wave electromagnetic simulations. The technique of utilizing capacitive and inductive source-load coupling to improve the performance of filters is fully researched. Advantages of using this type of filter are not only its compact size, but also its transmission zeros that can be independently controlled. Then, two dual-mode bandpass filters are designed, fabricated and tested to validate the design. Good agreement is achieved between the measured results and simulated ones.