Importance of the Antenna Model to Assess GNSS Multipath in Airport Environments

Abstract

For GNSS systems, the gain, phase and group-delay patterns of the receiver antenna have an impact on the pseudoranges, i.e. the apparent distances to the satellites estimated by the receiver. In the presence of multipath, this impact is difficult to assess because multipath and antenna effects are mixed. In this article, these sources of pseudo-range error are analyzed by means of simulations for an aircraft moving at the surface of an airport. For the simulations, we rely on a hybrid statisticaldeterministic GNSS multipath simulator combined with a receiver simulator. Various antenna models are tested, e.g. an ideal isotropic antenna and a realistic antenna mounted on an aircraft, with and without the phase and group-delay patterns.

GNSS Multipath Error Model for Aircraft Surface Navigation Based on Canonical Scenarios for Class F Airports

“…This way, each illuminated facet is seen as the origin of one multipath. The characteristics of the multipath are computed taking into account the antenna model which is detailed in [5] and [6].…”

“…The antenna model under FMRE does not render the frequency dependentbehavior of the antenna on the complete L1 C/A bandwidth (refer to [5]). In fact, the real antenna gain, phase and group delay are varying with the frequency but under the multipath simulator we only consider their value at the antenna central frequency i.e.…”

“…This electromagnetic model accounts for aircraft structure multipath as well as antenna gain, phase and group delay variations for all direction of arrival in the presence of the close fuselage. Details on this radiating antenna+aircraft model can be found in [5] and [6].…”