G. Avitabile

Microwave permittivity measurements through cross-shaped ring sensors

A microwave sensor designed to determine the complex permittivity of planar materials is proposed. The sensor is implemented using a full planar microstrip technology. The near fields of the ring resonator interact with the material under test (MUT) and the electrical characteristics of the resonator change. A scalar network analyzer is used to measure the resonant frequency and the corresponding amplitude of the transmission parameter for the fundamental mode. The complex permittivity is estimated by inverting the measured parameters using by an algorithm based on Artificial Neural Network (ANN). The proposed sensor is extremely compact and guarantees a good accuracy for low permittivity material. The design procedure is described and experimental results are reported validating the sensor performance.

Microwave system for moisture mapping by a linear array of slot sensors

A linear array of microwave sensors for moisture content mapping in thin or thick material sheets is introduced. The array building block is represented by a straight microstrip line electromagnetically coupled to a resonant slot structure properly loaded by two PIN diodes. Each array element constitutes a single slot sensor interacting with the material under test by means of the fields radiated through the slot. When the diodes are in the ON state, each sensor and, thus, the whole array, acts like a low loss transmission line. Otherwise, when the diodes are in the OFF state, the slots are allowed to resonate. Switching the array elements one at a time, the array electronically scans the specimen under test.

A versatile active antenna for low-cost microwave link applications

An active antenna which confgures a complete microwave receiving/transmitting front-end is inlroduced. The module is based on a single bipolar transistor which acts, at the same time, as the active device of the local oscillator, capable of being frequency locked by injection, and as the non-linear element in up/down conversion operations. The radiating structure is a rectangular patch, electromagnetically fed by two microstrips. A CAD oriented model of the radiating structure is discussed and simulation results of the active antenna are reported. Experimental results of a 2.4 GHz ISM Band prototype are discussed.

Coupling Between Inductances In GaAs MMICDesign

This paper describes the influence of the coupling between planar spiral inductors on the performances of a monolithic microwave linear circuit behaviour. An equivalent lumped-element model, developed using a full-wave approach, is discussed. The with the foundry model is compared with the standard foundry model. A GaAs MMIC LNA operating in 2.45 Ghz ISM-band is used as a benchmark for validating the model.