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This paper presents an overview of recent developments of millimeter-wave six-port technology dedicated to wireless sensing applications. In particular, complete solutions with features such as low cost, low-power consumption, compactness, robustness and ease of use are described. Radar and imaging applications are experimentally demonstrated to validate the approach proposed.
Robust tank level monitoring is an important issue in chemical and process industry and a challenging task if high accuracy has to be reached. The proposed sensor structure consists of a quasi-TEM mode waveguide on the one hand and an interferometric Six-Port receiver structure on the other hand. The waveguide structure itself in combination with the liquid to be monitored acts as a reflection phase...
In this work we propose the utilization of the Butler matrix as a six-port I/Q demodulator. The inherent symmetry of its topology allows to overcome the intrinsic amplitude and phase imbalances of the traditional approaches making it more suitable for the design of high performance six-port networks. To demonstrate the validity of the proposal a Butler matrix has been designed covering the complete...
Microwave interferometry enables the possibility of highly accurate distance measurements by evaluating phase differences. The reflected power is a function of the effective radar cross-section, the measurement distance, and the attenuation in air. An irradiated plain water surface shows a temperature-dependent behavior by means of the reflected power. This is due to the fact that the complex permittivity...
Six-Port receivers require a precise power measurement of all their four output channels. However, due to temperature drift, fabrication and component tolerances detectors' performance may have some degradation, which limits the measurement accuracy. Thus, an in-situ detector characterization is necessary. In this paper, a fast and simple solution for estimating the diode detector's characteristics...
This paper describes the realization of high performance millimetre-wave substrate integrated waveguide (SIW) components and integrated compact RF front-end modules using photoimaged trench vias on advanced multilayer thick-film technology. Contrary to widely used SIW with fence-post vias, advanced trench-filled vias form continuous metal (silver) side walls, enabling SIW to provide low loss and extending...
This paper reviews recent advances of technologies using radar sensor to detect vital sign of a human subject. A number of front-end architectures, detection methods, and system-level integrations have been reported to improve the detection accuracy and enhance the system robustness. The advantages of noncontact vital sign detection draw lots of attention in various applications, such as health-care...
A compact Ultra wideband (UWB) bistatic radar system has been developed. Lightweight, portable and low in power consumption, it uses low cost, off-the-shelf components, and is ideally suited for ranging, 3D-imaging, and wall characterization. Tests show excellent pulse width generation, resulting in very broadband transmission (0.5–5.5 GHz) and good receiver dynamic range, resulting in accurate measurement...
A new wireless tag design for a precise ranging system is presented. The proposed approach, based on a SAW delay line, is optimized for very low-power operation and low-cost manufacturing without compromising the measurement accuracy. Furthermore, the tag architecture allows the simultaneous use of the 2.4 GHz and the 5.8 GHz ISM bands, which may be used to improve the measurement resolution and accuracy...
A microwave-identification method that allows mobile phones to be utilized for indoor localization is proposed. Since the conventional localization method cannot identify specific microwaves because their identification code is encrypted, a system that utilizes web-access time as a measure of identification is proposed. In this system, a microwave is received at an access point (AP) at a certain web-access...
This paper presents several designs of multiband and solar rectennas. The procedure in order to perform multiband optimization of rectenna elements is presented and two design examples of 850 MHz/1850MHz and 915MHz/2.45GHz dual band rectennas are discussed. Additionally, two designs of compact solar rectennas where the solar cells share the area of the radiating element in the rectenna structure are...
In this paper, a wireless capacitive pressure sensor developed for the health monitoring of aircraft engines has been demonstrated. The sensing system is composed of a Clapp-type oscillator that operates at 131 MHz. The Clapp oscillator is fabricated on an alumina substrate and consists of a Cree SiC MESFET, thin film inductor, Compex chip capacitors and Sporian Microsystem capacitive pressure sensor...
The application of radar sensors to monitor vital signs is currently receiving much attention. Several radar architectures have been proposed in the technical literature for this task, although with some limitations. Here, a linear-frequency-modulated continuous-wave (LFMCW) approach is analyzed. By extracting the phase of particular range bins, precise tracking of vital signs (e.g., breathing) could...
Measuring the seismic activity of Venus is critical to understanding its composition and interior dynamics. Because Venus has an average surface temperature of 462 °C and the challenge of providing cooling to multiple seismometers, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents progress towards a seismometer sensor with wireless...
In this paper, a fully integrated active backscatter transponder based on the switched injection-locked oscillator (SILO) principle for frequency modulated continuous wave (FMCW) radar applications is presented. Furthermore, a novel theory to model the phase sampling behaviour of a SILO, accounting for noisy injection signals, is derived. The presented backscatter tag operates at 34.5 GHz and reaches...
Sensor networks as well as the Internet of Things, are getting more and more popular in many numbers of applications. However, a bidirectional link between the individual nodes is not always needed and leads to higher costs and power consumption. This paper introduces the concept Broadcast of Things which reverses the well known broadcast architecture. It is shown that in realistic environments the...
In wireless sensor networks, nodes having limited battery resources convey data to an energy-unconstrained base station. The amount of data transmitted by a node usually depends on how much local processing is performed. In other words, more computation on a node means less communication with the base station and vice versa. Hence improving energy efficiency and prolonging the network lifetime requires...
Complex image theory has been proposed as a means to efficiently calculate the fields induced by a magnetoquasistatic source above the earth. In position location applications, this has enabled an accurate determination of position from measured field strengths. While promising, complex image theory is only an approximation of the true field; inherent errors in position estimation occur due to the...
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