Micro-strip oscillator with dielectric resonator

#This invention relates to a microwave oscillator using a micro-strip line or more in particular to a microwave oscillator having an improved arrangement of a micro-strip line and a dielectric resonator.

#FIG. 1 shows an example of the basic construction of a general micro-strip line.

#FIGS. 2 and 3 show circuit diagrams showing examples of an oscillator circuit using the micro-strip line in FIG. 1.

#FIG. 4 is a sectional view for explaining the coupling condition between the strip conductor and the dielectric resonator of an oscillator circuit.

#Prior to explanation of embodiments of the invention, typical examples of the conventional microwave oscillator will be described below.

#A general construction of the micro-strip line is shown in FIG. 1. Reference numeral 1 shows a dielectric substrate, on the upper side of which a strip conductor 2 is formed, and a grounding conductor 3 is formed on the back side of the dielectric substrate 1. The strip conductor 2 and the grounding conductor 3 make up a parallel line for transmission of a signal. The grounding conductor 3 may alternatively be provided by a metal casing in which the dielectric substrate is arranged in close contact therewith, instead of being attached to the back side of the dielectric substrate 1. In such a case, only the strip conductor is formed on the upper side of the dielectric substrate. A Gunn diode or a field effect transistor (FET) is mounted on this micro-strip line, and a dielectric resonator of high quality factor is arranged at the side of the micro-strip line, thus making up a microwave oscillator. FIG. 2 shows an example of the construction of a microwave oscillator having a Gunn diode, and FIG. 3 that of a microwave oscillator having an FET.

#In FIG. 2, an output line 5 formed by a micro-strip line of a Gunn diode 4 is coupled to a dielectric resonator 6, and a bias voltage is supplied to the Gunn diode by bias means not shown, thus making up an oscillator. In order to achieve the maximum reflection at the resonance frequency of the dielectric resonator 6, the distance between the Gunn diode 4 and the coupling position of the dielectric resonator 6 is selected in such a manner as to form a self-oscillation loop between the Gunn diode 4 and the dielectric resonator 6, thus attaining oscillation at the resonance frequency of the dielectric resonator 6. This dielectric resonator is generally made of a material of Ti group, and has a resonance frequency depending on the dielectric constant and outline dimension thereof. At the present, such a dielectric resonator having quality factor of about 3000 to 5000 is sold on the market.