Abstract: A non-invasive, in-line fluid monitor includes a segment of fluid line disposed such that it and the fluid within become a part of the dielectric loading on an energized electromagnetic sensor device. Perturbations of the dielectric loading on the sensor device are monitored to determine certain fluid properties, such as pressure, composition, and the presence of air. The fluid line segment disposed through the electromagnetic sensor may be compliant and thus changes size in response to fluid pressure, altering the volume of the fluid line segment tin the cavity and altering the dielectric loading on the cavity. In one embodiment, a resonant cavity is used to encompass the segment of fluid line and a processor is used to compare changes in the resonant characteristics of the cavity to predetermined data to determine the properties of the fluid.

Abstract: A bulk semiconductor oscillator subassembly is carried on a support pin. The oscillator assembly includes a semiconductor diode mounted on the pin with one terminal connected thereto. The other terminal is connected to one end of an input coupling loop which has its other end connected to the pin through a by-pass capacitor. Biasing voltages are applied to the diode via a lead connected to the loop. The loop is coupled to a Yttrium Iron Garnet (YIG) sphere which serves as a resonator. The resonant frequency of the resonator is tuned by adjusting a DC magnetic field applied thereto. The output is obtained by an output loop which is located orthogonally with respect to the input loop and coupled to the YIG whereby the input and output loops are coupled through the YIG resonator.