Microwave and millimeter-wave UWB banpass filters using microstrip ring resonators

This paper presents our recent research works on microwave and millimeter-wave UWB bandpass filters using two types of microstrip ring resonators, including tab-coupled stubs-loaded ring resonators and parallel-coupled dual-mode ring resonators. Features and design methods of these ring resonators are described, and a number of example filters are provided, which show that these ring resonators are attractive in designing filters with compact size, wide passband, low insertions loss, and sharp passband skirt property.