A Monolithic Frequency Selective Structure With Dual-Band Quasi-Elliptic Filtering Response

This paper presents the design of a monolithic structure with dual-band quasi-elliptic frequency selective filtering responses. The frequency selective structure consists of a two-dimensional (2D) array of cavities apertured with six ring slots. The transmission response is with a quasi-elliptic passband in lower frequency, and an elliptic passband in upper frequency. By placing transmission zeros near the passband edge, the proposed structure is characterized with high selectivity, rapid rolloff, and high separation between two passbands. Besides, the working principles and influence of the dimensional parameters are fully investigated with simulations and analysis, which is helpful to the design. In this design, five resonances and three transmission zeros are obtained with a simple unit by introducing coupling and phase controlling. This work will be meaningful in study of three dimensional frequency selective structures with high performance.