Microstrip frequency discriminators based on quarter-wave band-stop filters

Microstrip frequency discriminators for a 5-bit instantaneous frequency measurement subsystem (IFMS) based on quarter-wavelength band-stop filters are presented in this paper. The rejection frequency is adjusted by the resonator length and its orientation, and the rejection bandwidth is tuned by the resonator distance from the main transmission line. In spite of the narrow stop bandwidth of a single resonator, an array of coupled resonators cause the wide stop bandwidth needed in discriminators. The proposed structure achieves compacts size and high stop-band rejection. Simulated results of the discriminators for the frequency range of 2-4GHz are presented. Frequency resolution of the presented discriminators is 62.5MHz.