Triangular spiral resonators for the design of front-end microstrip coupled circuits

This paper investigates the performance of a new microstrip resonator in a spiral shape for use in microwave devices such as filters, power dividers, multiplexers, etc. Its electromagnetic performance is here studied with the use of software CST Microwave Studio. Curves of coupling coefficients and external quality factor against physical dimensions are here produced for the triangular spiral resonator and also for a triangular open loop resonator for comparison. Simulation results have revealed that similar design performance as the one of the open loop resonator can be attained if the size of the spiral one is considerably reduced when both resonators have the same resonance frequency. Two Chebyshev two-pole microstrip filters were simulated and it was observed that reduction of 48 % in the area of the filter was achieved.