Microwave oscillators operate at extremely high frequencies. Accordingly, the assemblies which comprise microwave oscillators are very sensitive and must be manufactured with great precision. The resultant structures are very expensive and provide an oscillator which is very limited in tuning range. One class of microwave oscillators are referred to as dielectric resonator oscillators. The dielectric resonator is basically not tunable over a broad frequency range. The high dielectric constant of a dielectric resonator confines most of the electrical field internally, thus making it difficult to alter the resonant frequency significantly by external means. Furthermore, active circuitry associated with the dielectric resonator tends to be of a microstrip planar type and the oscillator frequency is dependent on the dielectric resonator spacial position with respect to the remainder of the oscillator circuitry.
Commercially available dielectric resonator oscillators have generally been limited to tuning range of a few percent. In addition, conventional wide-band microwave oscillators may exhibit frequency shifts when the oscillator module is exposed to a wide range of temperatures.