Novel trapezoidal planar dual‐mode bandpass filter using one single patch resonator

Microstrip bandpass filters are widely used in a variety of microwave systems, particularly in transmitter and receiver sections etc. to select a desired band of frequencies. However, common bandpass filters have deficiencies such as several resonators coupling, coupling gaps, only one attenuation pole in frequency responses, and so on. This paper proposes a triangular dual‐mode bandpass filter and two types of trapezoidal dual‐mode bandpass filters using one single patch resonators with corner cuts or crossed slots. It shows degenerate dual‐mode with corner cuts and unequaled crossed slots can improve the performances of filter greatly. The proposed filters have outstanding virtues such as novel and simple structures as they have one single patch without coupling gaps, small volume, easy integration and miniaturization, and so on.