Broadband YIG Tuned FET Oscillators

The association of a Ga As Field Effect Transistors (FET) and a Single Crystal Ferrimagnetic Garnets (YIG) has brought about the realization of oscillators electronically tunable in very broad bands. This paper presents the theoretical conception and the first experimental results of two types of FET-YIG oscillators. The first device is made up of a FET with a simple reactive inductance in the gate and tuned by a YIG sphere in the source. Its output power is 5 mW in the 7 - 11 GHz band. In the second device, the reactive inductance in the gate is replaced by a second YIG sphere. Tuned by the same magnetic circuit, these two YIGs have a theoretical widening of the oscillation zone towards a band of several octaves. Practical results illustrate this possibility in the 4 - 15 GHz range. The many applications of the Solid state tuned oscillators (sweepers, super heterodyne microwave receivers, spectrum analysers, etc...) give a clear indication of the interest of these first results.