A Small Printed Quadrifilar Helical Antenna for BGAN/GPS Applications

This paper presents an element of a 2×2element array antenna for Inmarsat BGAN/GPS applications. The element is an axial mode printed quadrifilar helical antenna that has been integrated with a compact feed network to provide sequential phase rotation for circular polarization (CP) radiation. The novel integrated lumpedelement feed network is designed to provide a balanced RF power to the four helix arms with a 90° sequential phase difference between them. The design maintains a low cross polarization, and accordingly, a high quality of RHCP up to ±66° over the transmit frequency band of 1616 MHz to 1626 MHz. The gain in this frequency range is higher than 3.5 dB with a return loss better than 11 dB and a perfect circular polarization performance (axial ratio ~0 dB). The proposed antenna has small size, light weight, low cost, almost hemispherical radiation pattern and excellent circular polarization that can become a good candidate in satellite L1band and BGAN satellite communications.