Multipath Suppression Capability and Indicators for Airborne Dual Frequency GNSS Antennas

Kurzfassung

Current satellite navigation systems are providing more and more dual frequency capabilities, enabling an unprecedented navigation accuracy and reduction of residual errors (e.g. from ionosphere). The aviation community has then started an effort to achieve new standardized minimum operational performance specifications (MOPS) for GNSS equipment, in order to allow for use of dual frequency multiconstellation (DFMC) systems in the future, with clear benefits in terms of obtainable navigation performance. In such scenario, residual errors due to the GNSS antenna become more and more relevant and actually need to be properly identified and bounded, both in the antenna specifications and, for instance, in the models for aircraft multipath. Previous work from the authors [1] has shown the methodology developed in order to accurately simulate the installed performance (both in terms of antenna pattern distortion and multipath) of commercial antennas mounted on commercial aircraft. The antennas are measured in an anechoic chamber and then imported into an electromagnetic simulation software, where they are used in combination with a proper airplane CAD model to simulate the real-life installation on the airplane. In this work, an analysis of the multipath performance obtainable by different antennas mounted on different aircraft (both single aisle and wide body) will be shown: such result will provide a good indication for the performance to be expected in real-life scenarios and will be also used to further validate (and ensure the general applicability of) the new proposed model for multipath, obtained from flight data and shown in a concurrent paper at the conference. Moreover, an indicator will be shown that is able to estimate the multipath suppression capability of the antennas: its applicability in the avionic context will be validate against the data obtained by the installed performance analysis and a proposal for its use in future antenna MOPS will be given.