Track 1: Waveforms and Signal Processing

This paper describes an antenna system combining Global Navigation Satellite System (GNSS) with Iridium satellite communications and UHF 225-512 MHz communications on a handset to provide an integrated Communications Navigation (Comm/Nav) antenna. The GPS/GNSS/Iridium antenna is a folded Quadrifilar Helix Antenna (QHA) with novel features which improve frequency coverage compared to existing QHA designs. This QHA antenna can be co-located concentrically (co-axially) around a UHF monopole which increases the gain of the monopole by several dB over most of the UHF communications band 225 512 MHz. Co-locating the QHA and monopole also reduces the area needed on the transceiver. The GNSS frequencies covered by the QHA include modernized GPS (L1, L2, L5), GLONASS, Galileo, and Beidou (Compass), spanning from 1164 to 1300 MHz and 1559 to 1611 MHz. The Iridium communications transmit and receive band (1611-1626 MHz) is also covered. The primary design goal for the QHA was to maximize Right-Hand Circularly Polarized (RHCP) gain at all GNSS frequencies and Iridium at angles from zenith down to 10 degrees above the horizon. A QHA is well suited to this application since it provides excellent RHCP coverage at all azimuth and elevation angles, as well as low crosspolarization to reduce multipath. The antenna patterns and gain are affected by the transceiver handset box upon which the antenna is mounted; for purposes of demonstration, the antennas were optimized and tested on a conductive handset box which was 8" long x 4" wide by 1.5" thick; no other ground plane was used. The diameter of the QHAs ranged from 0.75" to 1.5", so that each could fit on top of a handset. A 10-inch long UHF monopole or sleeve was included co-axially through the center of each QHA.