GHz Frequency Modulated Continuous Wave Research Articles

Development of GaAs Gunn Diodes and Their Applications to Frequency Modulated Continuous Wave Radar

In this work, we have designed and fabricated the GaAs Gunn diodes for a 94 GHz waveguide voltage controlled oscillator (VCO) which is one of the important parts in a frequency modulated continuous wave (FMCW) radar application. For fabrication of the high power GaAs Gunn diodes, we adopted a graded gap injector which enhances the output power and conversion efficiency by effectively removing the dead-zone. We have measured RF characteristics of the fabricated GaAs Gunn diodes. The operating current, oscillation frequency, and output power of the fabricated GaAs Gunn diodes are presented as a function of the anode diameters. The operating current increases with anode diameters, whereas the oscillation frequency decreases. The higher oscillation frequency was obtained from 60 µm anode diameters of the fabricated Gunn GaAs diodes and higher power was obtained from 68 µm. Also, for application of the 94 GHz FMCW radar system, we have fabricated the 94 GHz waveguide VCO. From the fabricated GaAs Gunn diodes of anode diameter of 60 µm, we have obtained the improved VCO performance.

Implementation and evaluation of coherent synthetic aperture radar processing for level measurements of bulk goods with an FMCW-system

Abstract. In industrial process measurement instrumentation, radar systems are well established for the measurement of filling levels of liquids in tanks. Level measurements of bulk goods in silos, on the other hand, are more challenging because the material is heaped up and its surface has typically a relatively complex shape. In this paper, the application of synthetic aperture radar (SAR) reconstruction with a frequency modulated continuous wave (FMCW) radar system for level measurements of bulk goods is evaluated. In the proposed monostatic setup, echo signals are acquired at discrete antenna positions on top of the silo. Spatially resolved information about the surface contour of a bulk good heap is reconstructed by coherent 'delay and sum' processing. The concept has been experimentally evaluated with a 24 to 26 GHz FMCW radar system mounted on a linear stepping motor positioning unit. Measurements on a thin metal wire at different range and on a curved test-object with a diffusely scattering surface have been performed to analyze the system's point spread function (PSF) and performance. Constant range and azimuth resolutions (−6 dB) of 15 cm and 8 cm, respectively, have been obtained up to a range of 6 m, and results of further evaluations show that the proposed concept allows more accurate and reliable level reconstructions of surface profiles compared to the conventional approach with measurements at a single antenna position.

Evolution Of A Suite Of Smart Millimetre Wave Radar Systems For Situational Awareness And Automation In Mines

Abstract This paper defines the issues required for the development of successful visualisation sensors for use in open cut and underground mines. It examines the mine environment and considers both the reflectivity of the rock and attenuation effects of dust and water droplets. Millimetre wave technology, as an alternative to the more commonly used laser and sonar implementations, is selected due to its superior penetration through adverse atmospheric conditions. Of the available radar techniques, frequency modulated continuous wave (FMCW) is selected as being the most robust. The theoretical performance of a number of 94GHz FMCW millimetre wave radar systems is determined and these confirm the capability of these sensors in the mining environment. The paper describes implementations of FMCW radar sensors for simple ranging, two dimensional line scanning and three dimensional imaging that are based on a common ranging module and in the case of the 2D and 3D applications, a common swash-plate mirror scanner. Data obtained during field trials in mines is presented to justify the selection of this technology

Seeing through dust and water vapor: Millimeter wave radar sensors for mining applications

AbstractThis paper defines the issues required for the development of successful visualization sensors for use in open cut and underground mines. It examines the mine environment and considers both the reflectivity of the rock and attenuation effects of dust and water droplets. Millimeter wave technology, as an alternative to the more commonly used laser and sonar implementations, is selected due to its superior penetration through adverse atmospheric conditions. Of the available radar techniques, frequency modulated continuous wave (FMCW) is selected as being the most robust. The theoretical performance of a number of 77 and 94 GHz FMCW millimeter wave radar systems is determined and these confirm the capability of these sensors in the mining environment. Implementations of FMCW radar sensors for simple ranging and three‐dimensional surface profiling are discussed before data obtained during field trials in mines is presented to justify the selection of this technology. © 2007 Wiley Periodicals, Inc.

THE DEVELOPMENT OF SIGNAL PROCESSING SYSTEM ON URBAN TRANSIT APPLICATION USING 77 GHZ FMCW RADAR

Ranging sensors usually use the Frequency Modulated Continuous Wave (FMCW) in order to track certain fixed moving objects. The FMCW must work accurately in a real environment, taking in the presence of back round echoes, atmospheric noises and weather predicaments. False detection of a moving target other than the intended target can be dangerous for the passenger and the vehicle. A high accuracy rate must be achieved through constant improvement of the FMCW. This paper reports on the development of the signal processing system for urban transit using 77 Ghz FMCW radar sensors.