Monitoring Solid Particle Deposition in Lossy Medium Using Planar Resonator Sensor

A very high-resolution, microwave microstrip-based planar resonator sensor is analyzed and presented for non-contact material sensing. The proposed sensor is an active feedback loop-assisted planar microwave resonator with an initial quality factor of 230, operating at 1.5 GHz. The active feedback loop compensates for the loss and power dissipation in the passive structure and increases the quality factor by several orders of magnitudes. The quality factor of the sensor is adjustable via the gain of the active device and relates exponentially to the bias voltage of the transistor. The resolution of the microwave device for permittivity sensing increases as the quality factor improves, which enables the user to take very precise measurements in different environments. The non-contact sensing distance from the sample can also be increased effectively because of the improvement in the quality factor and resolution. The potential use of the proposed device for the distance and location detection of a target sample in different environments of air, water, and sand, is also investigated.