Stefano Caizzone, Simon P. Hehenberger, Veenu Tripathi, Wahid Elmarissi, Institute of Communications and Navigation, German Aerospace Center (DLR), Germany

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Abstract:

Satellite navigation is a key element for safety-critical applications, such as aeronautics. In this context, both integrity and robustness need to be guaranteed. While at standardization level strong effort is being put in improved integrity models, there is still a lot of room for improvement in the quest for ensuring robustness, for instance against (intentional or not) jamming. On the other side, interference events are being reported more and more frequently, even and actually mostly in the vicinity of airports, hence posing an actual risk for aeronautics. The need for countermeasures grows therefore steadily. Multiantenna systems have been demonstrated in multiple fields to be a very effective way to contrast interferences, thanks to their capability of placing nulls in the direction of arrival of the interference, hence effectively suppressing its received power. While widely adopted in military aviation, their use in civil aviation has been till now limited, due to a combination of high cost, size and complexity, but also due to export rules (such as ITAR in US) prohibiting multi-antenna systems. Lately, these rules have been partly relaxed, so that small antenna arrays (with less than 4 elements for each band) can be used with no limitations both in US and EU. The present work shows the development of an ITAR-free antenna array, composed of 3 elements covering the L1/E1 band and 1 element for L5/E5a signals, hence compliant with future dual frequency multiconstellation (DFMC) usage. The antenna array is miniaturized so that it fully fits in an ARINC-743A footprint, such as the one used currently for single antenna installations. This feature is aiming at enabling adoption of the array for aircraft applications, due to the backward compatibility with the mechanical requirements and footprint. The conceptual suitability of miniaturized arrays for robust navigation has been shown in [1], highlighting limitations as well as capabilities of miniaturized arrays. The preliminary design of the array has then been shown in [2]. Since then, the array has been planned for flight on D-CODE, a Dornier DO-228 aircraft, part of DLR’s research fleet. In order to enable this flight campaign, several adaptions have been needed, resulting into an improved design, now including active electronics and calibration network as well as metallic adapters for installation on the plane. These improvements and the obtained performance will be shown in this paper. Moreover, both electromagnetic characterization and GNSS field tests will be shown, to validate its usability and suitability for robust navigation. Installed performance analysis once the antenna is mounted on the airplane will also be analyzed.