In this paper, two matched microstrip line configurations for the excitation of magnetostatic wave resonators have been studied for optimizing the performances of a Magnetostatic Wave (MSW) Straight Edge Resonator (SER). The first transducer was designed for a band-stop and the second one for a band-pass resonator, both suspended on a silicon micromachined membrane obtained by means of wet anisotropic etching. It has been previously observed that the insertion losses of microstrip lines on silicon membrane for band-stop and band-pass MSW SERs are improved with respect to the same microstrip line structures realized on a silicon bulk substrate. For that reason the modelling of the microstrip lines has been optimized in view of their application in SER devices. The Microwave Office program, a powerful tool for the design of microwave planar devices, has been used. The theoretical S-parameters have been obtained and optimized by changing the geometry in the design of the transmission lines.
Two band-stop SERs (resonator A and resonator B) on silicon membrane were obtained and characterized. The frequency tunability domain of these resonators was between 3 GHz and 9.5 GHz ca. obtained by changing the dc magnetic bias field between Happl = 0.02 T and Happl = 0.34 T. The measurements of the S21 parameter demonstrate a suppression of more than 20 dB of the high order modes, showing a good selectivity of this kind of resonator. The rejection ratio was better than -20 dB in the frequency domain from f = 3 GHz to f = 9.5 GHz for the resonator A and better than -20 dB between f = 4.2 GHz and f = 9.5 GHz for the resonator B. These results demonstrate the possibility to obtain microwave band-stop resonators supported on silicon membrane with high isolation and rejection ratios.