Markus Limbach

DLR-HR Compact Test Range facility

A Compact Test Range (CTR) facility shall extend the measurement capabilities at the Microwaves and Radar Institute of the German Aerospace Center (DLR) in Oberpfaffenhofen. Todays accuracy requirements in the RF-component characterization are decisive factors for the specification of a new measurement facility. Parts of a Compact Antenna Test Range (CATR) model 8074B, manufactured by March Microwave Systems B.V., have been purchased by the Institute in 2006. On the basis of these components, a compact test range in a new building named ‘HF-TechLab’ is currently under construction. It is planned to be operational at the end of 2009. An overview of the entire CTR facility is the objective of this paper.

Bistatic spaceborne-airborne experiment TerraSAR-X/F-SAR: data processing and results

Following an original proposal by the authors to the TerraSAR-X (TSX) scientific coordination board, a spaceborne-airborne bistatic experiment was successfully performed early November 2007. TSX was used as transmitter and DLRs new airborne radar system, F-SAR, as receiver; due to the capability of the latter to acquire data quasi-continuously, no echo window synchronisation is needed. Monostatic data were also recorded during the acquisition. This paper includes description and results of the spaceborne-airborne bistatic experiment, with special focus on data processing and image comparison. Given the acquisition scenario, with two-channel sampling and transmitter and receiver clocks operating independently, data processing must necessarily follow a three-step strategy: 1) channel balancing, 2) data synchronisation and 3) bistatic SAR processing. Since neither absolute range nor Doppler references are available in the bistatic data set, synchronisation is done with the help of calibration targets on ground and based on the analysis of the acquired data compared to expected data. Due to the variant nature of the bistatic acquisition and the required precision for the processing, data are processed using a bistatic backprojection approach.

F-SAR - recent upgrades and campaign activities

The F-SAR instrument represents DLRs advanced airborne SAR testbed for technology and remote sensing applications. The development of the instrument was triggered by a strong demand for data being simultaneously acquired at different wavelengths and polarizations as well as by the demand for very high range resolution. F-SAR is a modular development utilizing modern hardware and commercial of the shelf components. For the purpose of experiments and operational data acquisition campaigns the system is being installed on board a DLR Dornier DO228 research aircraft. This paper gives an overview of the instruments capabilities and performance, based on the multi-frequency and fully polarimetric imagery acquired during campaigns in the last two years. More specifically, campaigns in Greenland in 2015 (ARCTIC) and Gabon in 2016 (AfriSAR) are presented.