Toyon Research Corporation has developed a geodetic-quality GPS antenna based on a multi-arm helix. The antenna covers both L1 and L2 bands, exhibits cross-polarization rejection of more than 20 dB at and above the horizon, requires neither a large ground plane nor a choke ring, and weighs less than 150 grams. The uncompensated phase center error, as measured by NOAA, is less than 5.5 mm at L1 and 3.3 mm at L2. With compensation for variation with elevation angle, the phase center error should be correctable to a fraction of a millimeter. This antenna covers the entire 1559-1611-MHz GNSS upper band. However, its bandwidth around L2 is 1203-1265 MHz, only about half of the 1164-1300-MHz GNSS lower band. Toyon proposes to redesign the low-band helical windings of the current antenna to cover the full lower GNSS band. These changes will have little or no impact on the antennas weight or RF characteristics. Toyon will deliver a field-ready prototype of the GNSS antenna at the end of the Phase I.
Benefit: Geodetic grade GPS antennas on the market today are expensive and typically need large, heavy ground planes or choke rings. Toyons proposed GNSS antenna offers many advantages. It is based on a proven L1- L2 GPS system that has met or exceeded the performance of both choke ring and 6-arm pinwheel antenna designs in severe multipath environments. Calibration testing by NOAA shows very small phase center errors that should be correctable to less than 1 mm. Toyon is offering to design and prototype an antenna that will perform as well as the best geodetic antennas on the market, but cost a fraction of their price and weigh an order of magnitude less.
Keywords: Gps, Gnss, Antenna, Phase Center, Choke Ring, Multipath, Cross Polarization.
