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This paper deals with the development of a microwave noise-adding radiometer, which is purposely designed for the fire detection in forest environments. The sensor operates at 12.65 GHz and exploits commercial Satellite Television (SAT-TV) components such as a parabolic dish and a low-noise block. First, a simple system model is presented to estimate the radiometric contrast due to the presence of fire (increase in the antenna noise temperature with respect to the background) at a certain distance from the receiving antenna. Then, the design of the sensor is addressed, underlining the key technologies that allow the required performance to be attained at low industrial costs. An experimental characterization of the developed radiometer is reported focusing on both accuracy and sensitivity issues. Due to a continuous gain calibration based on the noise-adding procedure, the antenna noise temperature can be retrieved with an absolute error of 4 K without any thermal stabilization of the instrument electronics. Last, real fire detection experiments have been carried out both in laboratory and open-space environments. A radiometric contrast of 8.8 K has been recorded for a wooden fire of 0.2 [m.sup.2] placed at a distance of about 30 m from the antenna. Index Terms--Calibration, fire detection, microwave radiometry, microwave receivers, remote sensing.

This paper presents a design methodology for common-mode (CM) stability of operational transconductance amplifier (OTA)-based gyrators. The topology of g m − C active inductors is briefly reviewed. Subsequently, a comprehensive mathematical analysis on the CM stability of OTA-based gyrators is presented. Sufficient requirements for the gyrator's CM stability, which easily can be considered during the design process of common-mode feedback (CMFB) amplifiers, are defined. Based on these stability requirements, a design methodology and a design procedure are proposed. Finally, in order to validate the proposed procedure, a resonator with 20 MHz resonance frequency and a quality factor of 20 is fabricated with UMC 180 nm complementary metal-oxide-semiconductor technology, and its CM stability is examined. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

According to a recent European Union report, lighting represents a significant share of electricity costs and the goal of reducing lighting power consumption by 20% demands the coupling of light-emitting diode (LED) lights with smart sensors and communication networks. In this context, this paper proposes the integration of these three elements into a smart streetlight, incorporating a 24GHz phased-array (Ph-A) front-end (FE). The main building blocks of this Ph-A FE integrated in a low-cost 90nm complementary metal-oxide-semiconductor (CMOS) technology are fully characterized. The selected FE's architecture allows the implementation of transceivers as well as Doppler radar sensors functionalities. More specifically, the Ph-A technology is applied to a Doppler radar sensor in order to realize multi-lane road scanning and pedestrian detection. That way, the smart streetlight can become eco-friendly by turning on the LEDs only when necessary as well as to measure traffic parameters such as vehicle speed, type and direction. Intercommunication between the smart streetlights is based on a time-sharing mechanism that uses the same FE reconfigured as transceiver. Thanks to this functionality, the recorded traffic information can be relayed through adjacent streetlights to a control center, and control commands and warnings can be spread through the network. The system requirements are derived assuming a simplified model of the operating scenario with a typical inter-light distance of 50m and line-of-sight between lights. The radar range is around 60m, which allows for continuous coverage from one streetlight to the adjacent one. Meanwhile, a communication range of 140m is derived as a fundamental requirement for reliable communication between streetlight sensors because it allows bypassing of one node in case of failure. For the developed building blocks -- a low-noise amplifier, a variable-gain amplifier, a voltage-controlled oscillator and a vector modulation phase shifter -- the design methodology is presented together with measurement results. The system power, consumption, noise figure and gain are estimated by means of a system analysis based on the measured data from the implemented blocks and the state of the art performances for the missing parts. It is shown that the requirements can be fulfilled with a total power consumption of around 375mW in Doppler radar sensor mode and around 190mW in transceiver mode. To the authors' knowledge, this kind of integration is new and overcomes some limitations of the currently used solutions based on infrared sensors and low-throughput communications. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of fire detection in the presence of obstacles that are nontransparent to visible or infrared wavelengths. Exploiting the obstacle penetration capability of microwaves, a solution based on passive microwave radiometry has been proposed. To investigate such a solution, a theoretical model of the scene sensed by a microwave radiometer is developed, accounting for the presence of both fire spot and wall-like obstacles. By reversing the model's equations, it is possible to directly relate the obstacle emissivity, reflectivity, and transmissivity to the antenna noise temperatures measured in several conditions. These temperatures have been sensed with a portable low-cost instrument. The selected 12.65-GHz operation frequency features good wall penetration capability to be balanced with a reasonable antenna size. In order to verify the aforementioned model, several fire experiments have been carried out, resulting in an overall good agreement between measurements and developed theory. In particular, a 2-cm-thick plasterboard wall, typically used for indoor building construction, shows a transmissivity equal to 0.86 and can easily be penetrated by a microwave radiometer in the X-band. [ABSTRACT FROM AUTHOR]