Magnetostatic wave resonators and oscillators

The purpose of this paper is to describe the current status of magnetostatic wave tunable resonators operating between 2 and 12GHz and their applications to microwave oscillators, the wave propagating in a pure yttrium-iron-garnet epi-layer. The first section deals with magnetostatic surface wave (MSSW) resonators consisting of a pair of reflective grooved gratings and two microstrip-transducers set between the gratings. Results on insertion loss, off-resonance frequency rejection andQ value are presented. However MSSW cavities suffer several disadvantages such as the small saturation power level at low frequencies and the difficulty to temperature compensate MSSW devices. These problems are overcome with magnetostatic forward volume waves (MSFVW). Then the second section is devoted to MSFVW resonators. A peculiar folded geometry made of five grooved gratings and two microstrip-transducers has been designed to provide a sufficient out-of-band rejection. The experimental characteristics of these resonators are given. In the last section of this paper are reported the features of tunable oscillators implemented with MSSW and MSFVW resonators in a hybrid configuration. Results about tunability, output power,FM phase noise are reported. MSFVW resonator stabilized oscillators are very promising and magnetostatic wave resonators seem a challenge to YIG spheres.