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2. Millimetre wave SAR for UAV operation

Author

Asia-Pacific Microwave Conference (25th : 2011 : Melbourne, Vic.), Essen, Helmut, Stanko, Stefan, Sommer, Rainer, Johannes, Winfried, Wahlen, Alfred, Wilcke, Jorn, and Hantscher, Sebastian

Published
2011

5. On the scattering mechanism of power lines at millimeter-waves

Author

Essen, Helmut, Boehmsdorff, Stephan, Biegel, Gregor, and Wahlen, Alfred

Subjects
Remote sensing -- Methods, Remote sensing -- Investigations, Power lines -- Measurement, Power lines -- Investigations, Company legal issue, Business, Earth sciences, Electronics and electrical industries
Abstract

The radar signature of power lines is of high importance in the design of systems for helicopter collision avoidance. Laboratory measurements have been reported recently, but field measurements at millimeter waves are missing. The contribution describes measurements done in ground-based configuration with a real aperture scanning-beam radar operating simultaneously at 35 and 94 GHz. By scanning, an aspect angle interval of 60[degrees] was covered, including the broadside aspect. The narrow beam width allowed to discriminate between different wires separated horizontally. While these measurements were done under a very shallow incidence angle, assisting measurements were done with the same radar mounted into an aircraft using synthetic aperture radar techniques. The results for shallow and steep incidence are compared and show the significant influence of this parameter on the signature of the power line. Additionally the measurement results are compared with those from model calculations. Index Terms--Millimeter waves, modeling, power lines, RCS, synthetic aperture radar.

Published
2002

6. Real-time radar imaging based on UAV platforms

Author

ESSEN, Helmut and HANTSCHER, Sebastian

Abstract

[ABSTRACT]A miniaturised millimetre wave UA V-Synthetic Aperture-radar, MRUDIO, was designed, built and tested onboard a microlite aircraft and an unmanned helicopter. The design was conducted at Fraunhofer-FHR and followed the FMCW principle, to get the highest possible average transmit power and thus the best range performance. A very flexible principle of operation, based upon multiplication of basic frequencies generated using a DDS oscillator, allows a very easy adaption of the band of operation between 35 GHz and 94 GHz. The experiments described here were conducted at an operating frequency of 94 GHz. An inertial system of high quality, based upon a fibre optic gyroscope maintained the necessary precision, to allow high resolution SAR imaging. The raw data are transmitted to the ground station using an analogue data link, where they are AID converted, preprocessed and finally undergo a real-time SAR-focusing algorithm. Additionally to the quicklook processing the data are stored to be able to apply further high quality SAR processing. The mm-wave system can also be incorporated into a UA V-SAR developed at !radar of Melaka (My) to serve applications with high sensitivity against small scale structures and changes at mm W-bands and better transmission through canopies of wood at lower frequencies. The paper describes the design principles and gives results from the flight tests.

Published
2012

7. Radar Technoligy For Heliostat Position Conrol

Author

Klimek, Jasmin, Sauerborn, Markus, Hoffschmidt, Bernhard, Sieger, Stefan, Biegel, Gregor, Essen, Helmut, Hilger, Patrick, and Göttsche, Joachim

Subjects
solar thermal power plant, synthetic aperture, millimetre wave radar, heliostat, position control, remote monitoring
Published
2012

15. High resolution W-band UAV SAR

Author

Essen, Helmut, primary, Johannes, Winfried, additional, Stanko, Stephan, additional, Sommer, Rainer, additional, Wahlen, Alfred, additional, and Wilcke, Joern, additional

Published
2012
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34. Metamorphic HEMT MMICs and Modules for Use in a High-Bandwidth 210 GHz Radar

Author

Tessmann, Axel, primary, Kallfass, Ingmar, additional, Leuther, Arnulf, additional, Massler, Hermann, additional, Kuri, Michael, additional, Riessle, Markus, additional, Zink, Martin, additional, Sommer, Rainer, additional, Wahlen, Alfred, additional, Essen, Helmut, additional, Hurm, Volker, additional, Schlechtweg, Michael, additional, and Ambacher, Oliver, additional

Published
2008
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35. A 3-D millimeterwave luggage scanner

Author

Haegelen, Manfred, primary, Stanko, Stefan, additional, Essen, Helmut, additional, Briese, Gunnar, additional, Schlechtweg, Michael, additional, and Tessmann, Axel, additional

Published
2008
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36. A high performance 220-GHz broadband experimental radar

Author

Essen, Helmut, primary, Stanko, Stefan, additional, Sommer, Rainer, additional, Wahlen, Alfred, additional, Brauns, Ralf, additional, Wilcke, Joern, additional, Johannes, Winfried, additional, Tessmann, Axel, additional, and Schlechtweg, Michael, additional

Published
2008
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48. Localisation of concealed worn items using a millimeter wave FMCW radar.

Author

Hantscher, Sebastian, Hagelen, Manfred, Lang, Stefan, Schlenther, Beverly, Essen, Helmut, and Tessmann, Axel

Abstract

In this paper, the setup of a rotating 94 GHz millimeter wave FMCW radar for passenger inspection on airports is presented. The radar frontend comprises 5 receive channels in order to look the person under test from different aspect angles. A special focus is on the calibration of the integrated VCO of the radar module. Its non-linearity has to be compensated precisely. Else, the phase of the intermediate frequency signal gets distorted which degrades the image resolution. Test measurements performing a 360 degree scan show the ability of the scanner to detect and localize dangerous metallic as well as non-metallic objects worn concealed under the cloths. [ABSTRACT FROM PUBLISHER]

Published
2011

49. Millimetre wave SAR for UAV operation.

Author

Essen, Helmut, Stanko, Stefan, Sommer, Rainer, Johannes, Winfried, Wahlen, Alfred, Wilcke, Jorn, and Hantscher, Sebastian

Abstract

Most recent developments in millimetre wave technology at W-band, especially the advance of medium power and low noise HEMT amplifiers, allow the set-up of miniaturized radars, operating with a wide RF bandwidth, achieving high range resolution. A highly miniaturized FM-CW radar at 94 GHz was developed and tested for SAR applications onboard small UAVs and within a sensor package to be used with a small airborne sensing aircraft. Advanced front-end technique was combined with off-the-shelf GPS and transmission equipment which is readily available. The main goal of the research project is to show, that new front-end technology in combination with achievable back-and components can lead to a SAR system, which is capable to serve a wide field of applications, as environmental monitoring, border control, agricultural applications and equally well can serve the needs of military reconnaissance applications. The paper describes the current state of the research project and gives the perspective of a later prototype production by a Fraunhofer Spin-off. [ABSTRACT FROM PUBLISHER]

Published
2011

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