In-Situ Calibration of Antenna Arrays for Improved Spatial Signal Processing Using In-Space GNSS Signals

Receiving GNSS signals with an antenna array enables several additional applications. It allows for spatially adaptive processing such as beamforming and nulling, or measuring the phase differences between the elements of the antenna array to estimate the directions of arrival of impinging signals. In order to make the best use of these applications, it is necessary to know the radiation pattern of the antenna array. Classically, the pattern is measured ex-situ beforehand. However, since the surroundings at the site of operation change the reception characteristics of the antenna, a pattern measured in this way deviates from the actual one. In this paper we present an approach for in-situ calibration of an antenna array. The resulting reception pattern stores the delay differences between the antenna elements as a function of the direction of incidence. The superiority of an in-situ pattern over a classical pattern is demonstrated in this paper using a method for determining the attitude of the antenna array.