Grégory Bonin

A Ka Band Imaging Radar: DRIVE on Board ONERA Motorglider

Following previous studies, a concept of low-cost imaging Ka-Band radar is presented in this paper. This radar is integrated into under-wings pods that are fixed on a STEMME S10VT motorglider. This radar concept combines real aperture in the cross-track direction, by the antennas geometrical aperture, and synthetic aperture in the along-track direction, realized with the aircraft motion. Radar front-end uses FMCW (for Frequency Modulated Continuous Wave) technique which allows to reduce the power emission to a few Watts. In addition, the use of the millimeter band induces antennas size reduction, and makes possible the radar integration into pods. Thus, radar particularities are a low- size, a low-weight and a low-cost basis, making this radar suitable for future integration on board small vehicles, such as UAV (Unmanned Aerial Vehicle). The radar definition and specifications will be exposed, together with the first results obtained on April 2006. Two ways of operation will be exposed: An application as vertical sounder, using cylindrical horn antennas, and an application as SAR radar, using rectangular antennas. The two cases will be illustrated by samples of results.

The ONERA RAMSES SAR: latest significant results and future developments

The last SAR campaigns of the French ONERA RAMSES system have been dedicated to various applications, military or civilian, including very-high resolution, FOPEN (Foliage penetration) in cooperation with the FOI, MTI, bistatic SAR and vegetation characterization. These different projects gave us the opportunity to improve our SAR processing procedure (very high resolution) and to develop new algorithms (bistatic scenario). In parallel, the ONERA team has developed and applied many techniques (polarimetric analysis, PolInSAR, wavelet analysis) which proved to be efficient in these different thematic context. The current aircraft platform, a Transall C160 will be decommissioned at the end of 2008. In order to maintain our activities, we are developing a new system family compatible with smaller aircrafts. The challenge is two fold : migrating the existing radars in a airplane four times smaller and maintaining our innovation capabilities with the development of new radar concepts. These paper presents the most recent results on SAR techniques and describes the status of the development of the RAMSES successors : the first, SETHI, dedicated to military applications and earth observation, the second, BUSARD more focused on UAV applications.

ONERA SAR facilities

This paper provides an overview of the airborne SAR systems developed by the French Aerospace Lab ONERA over the past five years. The first system, called SETHI, is presented in the first section. It has been developed according to the standard FAR25 applied to civil application. The main improvement compared to the previous ONERA airborne radar system RAMSES is that the antennas are located into two pods compatible with small aircrafts like the Falcon 20. This pod-based configuration allows the easy integration of any kind of payloads under the single certification of the pods by authorities. The second section describes the BUSARD concept, dedicated to UAV-like payloads. A special attention is set on its Ka-band radar payload. Finally, we describe the RAMSES NG project, with a new installation on board a Falcon 20 aircraft and we expose the latest X-band developments. The three systems are summarized on overview tables.

The New ONERA Multispectral Airborne SAR System

This paper provides an overview of the new airborne SAR system developed by the French Aerospace Lab ONERA over the last two years. This system, called SETHI, was developed according to the standard FAR25 applied to civil application. The main improvement compared to the previous ONERA airborne radar system RAMSES is that the antennas are located in two pods compatible with small aircrafts like the Falcon 20. This pod-based configuration allows the easy integration of any kind of payloads under the single certification of the pods by authorities. In the first section a quick introduction presents the aircraft configuration (cabin and pods) with an overview of SETHI development. The second section describes the SETHI concept with the installation on board the Falcon 20 cabin, the hardware development to control and command all ONERA racks, the pods with their control and command systems. The last section illustrates the validation campaign which took place in September 2007 at Ni circmes Garons Airport in France.

ONERA AESA sensors developments

Since a few years ONERA has been investing in new radar architecture concepts. CURACAO and Ramses NG are airborne radars based on AESA antennas, T/R-Modules and compact and modular microwave modules. This paper will describe these designs and first test results.