The GPS Block IIR and IIR-M Broadcast L-band Antenna Panel: Its Pattern and Performance

Abstract

The Global Positioning System (GPS) Block II Replenishment (IIR) space vehicle (SV) has made up at least one-half of the GPS constellation since 2006. This consists of the 12 original 'classic' IIR SVs and the eight 'modernized' IIR-M SVs. As a stepping-stone toward the IIR-M modernization, Lockheed Martin developed and deployed an updated version of the satellite antenna panel for the L-band broadcast signal. This is the signal used by the worldwide GPS user population. This paper describes both antenna panel versions, their broadcast signal patterns, the performance observed in factory testing, and their on-orbit performance. This is the initial publication of these antenna panel patterns. Ground and on-orbit measurements of both versions of the antenna show that all specification requirements are exceeded. They also reflect the increased antenna gain for the new IIR antenna. The L1 signal shows an increase of 1 dB in received power at edge of Earth, and L2 shows an increase of 2 dB in received power. All users, both terrestrial and on-orbit, benefit from this enhanced power profile.

Tri‐orthogonal polarization diversity reception for non‐geosynchronous satellite orbit ionospheric channels

“…Considering the Orbcomm system, for the gain profiles of waveforms transmitted with polarizations and at T, we place a shaped profile according to , where a 0.8 dBic gain is observed at broadside, or α =0°, which increases to a maximum of 3.7 dBic at 55° off‐nadir, or α = 55°. For the Iridium and GPS systems, we introduce ideal conical beam gain profiles at T which compensate additional free space path loss for non‐nadir path propagation . Transmit frequencies for the Iridium and GPS L1 systems are close together, straddling 1.6 GHz, and as such, receive antennas are typically packaged to cater for both as a patch‐style unit .…”

Potential impact of global navigation satellite services on total power H i intensity mapping surveys

“…Steigenberger et al 2017). Variations due to the beam pattern of the satellites are also neglected as the beam is designed as such that there is no more than a factor of two difference between transmissions at the zenith and the horizon (Montesano et al 2007;Marquis & Reigh 2015). There is also a GPS L3 service at 1381.05 MHz that is not modelled as this is an intermittent broadcast.…”

Characterization of On-Orbit GPS Transmit Antenna Patterns for Space Users

“…The 16 deg off-boresight angle mask corresponding to a height of ray path (HORP) altitude of approximately 1200 km; measurements below this mask were not processed due to perturbation from passing close to the limb of the Earth. Figures 10 and 11 show side-by-side comparisons between the GPS ACE reconstructed patterns and ground-based gain pattern measurements [5] for Block IIR and IIR-M, respectively. It is immediately apparent that GPS ACE reconstructed antenna patterns demonstrate excellent agreement with the antenna patterns measured by Lockheed Martin before launch, with both gross and fine-scale features common to both data sets.…”

“…Comparison of Block IIR-M ground measured antenna pattern (a)[5] to reconstructed antenna pattern from GPS ACE flight data (b) as heat maps out to 90 deg off boresight.…”