Quadrifilar Helical Antennas (QFHA) are one of the best candidates to provide a high gain, shaped beam with excellent circular polarization axial ratio for satellite radio and mobile satellite phone system. One of the most compelling reasons to use these antennas for digital radio and mobile satellite system is their ability to shape the beam so as to provide mode gain in the regions where the satellite is between the horizons the zenith. Depending on the satellite constellation orbital design, a dip in the antenna gain pattern could be tolerated when the satellite is overhead, because the slant range is minimized.

The Antenna Products Division (APD) of Astra Microwave Products Limited (AMPL) developed deferent different models in L, S and C band with low cost and good characteristic.

The QFHA is vertical antenna, but it can be designed to be low profile, and perhaps retractable, especially for applications in the more compact hand-held mobile satellite systems. For the satellite radio systems, the antennas are primarily used on the roof of the vehicles. It is likely that these antennas will be preinstalled in future automobile models. For mobile satellite phones, however, the hand held units will be the most likely beneficiaries of these antennas. The mobile satellite phone systems for automobiles could also require a similar antenna mounting on the top of the vehicles.