The development of an active retrodirective antenna involving frequency conversion stages is presented. This retrodirective array of printed dipoles and regular commercial components is designed to operate at the GSM1900 band. Experimental measurements of monoestatic and biestatic responses are given, showing very good performance for a small retrodirective array.

This paper presents a new modeling approach accounting for the nonlinear description of low-frequency dispersive effects (due to thermal phenomena and traps) affecting electron devices. The theoretical formulation is quite general and includes as particular cases different models proposed in the literature. A large set of experimental results, oriented to microwave GaN power amplifier design, is provided to give an exhaustive validation under realistic device operation

No abstract

No abstract

The small-signal equivalent circuit modeling of microwave field-effect transistors (FETs) is an evergreen and ever flourishing research field that has to be up-to-date with technological developments. Hence, modeling techniques must be continuously adapted and extended to suit best evolving technologies. The extraction of a FET high-frequency small-signal equivalent circuit is a very active and broad research area of significant interest, owing to its use as a prerequisite for noise and large-signal modeling. The aim of this invited article is to provide in-depth knowledge, critical understanding, and new insights into how to extract a FET small-signal equivalent circuit from both theoretical and practical perspectives. To illustrate potential solutions to the key challenges faced by researchers, experimental results for different semiconductor technologies are reported and discussed. The study is focused on the hot research topic of the cold approach that has been, and still is, the most widely used technique for extracting FET small-signal models and on the active role of the transconductance for successful modeling. V C 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:749-762, 2016.

No abstract

Innovative technology approaches have been increasingly investigated for the last two decades aiming at human being long-term monitoring. However, current solutions suffer from critical limitations. In this paper, a complete system for contactless health-monitoring in home environment is presented. For the first time, radar, wireless communications, and data processing techniques are combined together enabling contactless fall detection and tag-less localization. Practical limitations are considered and properly dealt with. Experimental tests, conducted with human volunteer in a realistic room setting, demonstrate an adequate detection of the target's absolute distance and a success rate of 94.3% in distinguishing fall events from normal movements. The volunteers were free to move in the whole room with no constraints in their movements.

No abstract