First Interferometric Trials with the Airborne Digital-Beamforming DBFSAR System

The Microwaves and Radar Institute of the German Aerospace Center (DLR) is known for its consistent work on the field of airborne Synthetic Aperture Radar and its application. Currently, the Institute is developing a new advanced airborne SAR system, the DBFSAR, which is planned to supplement its operational F-SAR system in near future. The development of DBFSAR was triggered by the various evolving digital beamforming (DBF) techniques for future space-borne SAR systems and the need for an airborne experimental platform for preparation of such missions. Additionally, there is a demand for very high resolution SAR imagery, which cannot anymore be fully satisfied with the existing F-SAR system. This paper should give an overview over the current status and performance of the DBFSAR system, including interferometirc results from test flights performed in spring 2017

Cavity Backed Capacitively Coupled Stacked Patch Element for Electrically Small P-Band Array

The Microwaves and Radar Institute at the German Aerospace Center operate an airborne multi-frequency, polarimetric, imaging SAR system. The F-SAR sensor is equipped with a variety of different antennas, based on patch technology. A new antenna element is developed for the P-Band frequency range from 400 to 470 MHz. Due to the requirements of the aircraft the size of the antenna array, and therefore of each single element, is reduced to a minimum. A cavity backed, capacitive coupled stacked patch element is designed and presented in this paper

Antenna Range Measurements for Airborne Remote Sensing Antennas

The DLR Compact Test Range (CTR) is a dual reflector compact range in an electromagnetically shielded chamber for antenna and Radar Cross Section (RCS) measurements under far-field conditions [1]. The quiet zone dimensions allow an evaluation of a volume under test, containing the antenna under test (AUT) in position on the original support structure and surface. Precise in-situ parameters offer extra information about the installed AUT characteristics. These properties are particularly substantial for the radiometric and the polarimetric correction of the propagating signals in imaging microwave sensors, such as Synthetic Aperture Radar (SAR) instruments. F-SAR [2] is a high-resolution multi-frequency fully polarimetric airborne SAR with interferometric capabilities that is developed and operated by the DLR Microwaves and Radar Institute. Spherical swept frequency antenna measurements with continuous moving axis and forward/reverse scanning on offset position AUTs impose specific demands on the analysis. Higher order modes that are present due to test setup and physical constraints are considered in the post-processing. Still, stray signals from the antenna carrying aircraft structure in the proximity contribute to the antenna pattern and remain unfiltered. The particular requirements and status of the applied measurement and processing techniques are described

New Cavity Backed Capacitively Coupled Stacked Patch Element for P-Band SAR Application

The Microwaves and Radar Institute at the German Aerospace Center operate an airborne multi-frequency, polarimetric, imaging SAR system. The F-SAR sensor is equipped with a variety of different antennas, based on patch technology. A new antenna element is developed for the P-Band frequency range from 400 to 470 MHz. Due to the requirements of the aircraft the size of the antenna array and therefore of each single element, is reduced to a minimum. A cavity backed, capacitively coupled stacked patch element is designed and presented in this paper

A 5 way lumped-elements Wilkinson power divider

This paper presents the design of a symmetrical unequal lumped-elements Wilkinson power divider with 5 output ports operating at center frequencyf_r=435 MHz, which will be used for the airborne DLR F-SAR system [1] to investigate multifrequency polarimetric SAR applications. Based on theoretical and simulated analysis an appropriate design has been developed regarding to the electrical system specifications like the high-power purposes. On the other hand, the mechanical layout is a major aspect for an airborne SAR system, hence it was very important to realize a very compact, cost efficiency and light weight design. A first in-house manufactured prototype was set up and the analysis of the measured parameters matches both the electrical and mechanical design goals very well, confirming the validity of the proposed design

DLR – F-SAR P-Band Antenna – Design, Measurements and Results

The airborne synthetic aperture radar system, operated by the Microwaves and Radar Institute, is now equipped with an operational P-band subsystem. Antenna design, measurements and first results are presented. Due to the airborne platform antenna elements with reduces physical dimensions were developed, composing an antenna group of 25 dual polarized elements. With two switchable power divider networks the antenna can support a nadir looking sounder mode as well as the standard side looking SAR mode. This paper shows antenna measurements inside the Institutes antenna measurement facility and in flight performance

New Airborne SAR Antenna at P-Band

New P-band antenna for airborne SAR. The BIOMASS frequency range 410 to 460 MHz is covered by a new antenna array. With two SAR modes and a DBF-SAR configuration the antenna gives new impulses to low frequency earth observation purposes

P-Band Antenna Array for Airborne SAR Application and DBF SAR Demonstration

The Microwaves and Radar Institute at the German Aerospace Center operate an airborne multi-frequency, polarimetric, imaging SAR system. The F-SAR sensor is equipped with a variety of different antennas, based on patch technology. A new antenna is developed for the P-Band frequency range from 400 to 470 MHz, covering the Biomass mission requirements. The size and weight of the antenna array, and therefore of each single element, is reduced to a minimum. A cavity backed, capacitive coupled stacked patch element is basis for the new PII-Band antenna array