Modal Filter Based on a Microstrip Line with Two Side Conductors Grounded at Both Ends

The article presents the results of a study of a modal filter (MF) based on a microstrip line with two side conductors grounded at both ends. New analytical expressions for calculating the time response in such a structure are given. For their validation, an MF prototype was made and the transmission coefficient was measured in the frequency range from 0 to 12 GHz. In addition, the full-wave electrodynamic simulation and the analysis based on the transmission line theory were carried out. The frequency responses of the MF were converted into time domain responses in the ADS system. At the MF output, the response to an ultra-wideband (UWB) pulse was analyzed. The results for the analytical model are in good agreement with the results of measurements and simulations by the two approaches. It was experimentally proven that the structure under study provides the protection of electrical circuits from a UWB pulse by separating it in time and decreasing its effect on the components.