Compact band pass filter using triangular open loop resonator

Recent developments in wireless communication challenges microwave filters with more demanding requirements such as small size, light weight, high performance and low cost. Microstrip resonator have the higher performance than the conventional filtering technique for microwave devices. A triangular open loop resonator energized using electromagnetic (EM) and edge coupling is presented in this paper. Microstrip line is modified as a triangular open-loop resonator that introduces additional capacitance and inductance by re-orientation of electromagnetic field, there by selecting the operating frequencies. Depending on the type of coupling and position of the feed used the operating frequency of the filter changed for the same dimensions. EM and edge coupling is given to the resonator, when its gives band pass filters at 2.45 GHz and the effect of each coupling techniques are studied in detail. Better size reduction is observed for EM coupling than the edge coupling. The filters characteristics are analyzed in substrate FR4 epoxy by using ANSYS High Frequency Structure Simulator (HFSS) software. The design equations for the resonator predicts the frequency with less than 2% error with the simulated frequency. The optimized triangular open loop resonators are fabricated and validated using Keysight ENA 5080A Vector network Analyser. The simulated and measured of the resonator filter are comparable for center frequency, bandwidth, return loss and attenuation.