Optimization of a Miniaturized Printed Quadrifilar Helical Antenna for BGAN/GPS Applications

This paper presents the design of an element of a steerable 2×2 array antenna for GPS and BGAN applications. The element is a printed quadrifilar helical antenna which an integrated sequential phase shift rotation feed employed to enhance the circular polarization (CP) characteristics of the antenna. The integrated feed network is designed to provide a balanced RF signal to the four helical arms with a 90ᵒ sequential phase difference between them. The antenna maintains a low cross polarization up to ±60ᵒ, over transmit and receive frequency coverage from 1525 MHz to 1660 MHz, a return loss better than 11 dB with RHCP performance, and an axial ratio below 1.9 dB. The proposed antenna has a compact size, low cost and light-weight, with a relatively wide bandwidth, and almost-hemispherical radiation pattern with excellent right hand CP radiation that is suitable for L1-band GPS and BGAN satellite communications.