Moderately compact helix antennas with cutoff patterns for millimeter RTK positioning

Abstract

Helical antennas have been developed that feature a cutoff pattern and are suitable for practical positioning at millimeter level. The antennas are in the form of a tube with 3 cm in diameter and 40 cm in height. The antennas provide 20-dB suppression of the reflections from the earth surface, starting from low elevations. Open sky tests have demonstrated that the multipath contribution to the real-time positioning error falls below thermal noise. By smoothing the noise, these antennas achieve a positioning accuracy of 1 mm RMS in the vertical coordinate and 0.7 mm in the horizontal in almost real time.