Compact GNSS Antennas

Compact GNSS Antennas

Global Navigation Satellite Systems (GNSS) are well established and applications are expected to increase in the foreseeable future. Applications include navigation and positioning for a very wide variety of vehciles, people and high-value commercial goods. However, systems such as GPS and Galileo operate at microwave frequencies around 1GHz where the microwave of signals is about 30cm. An antenna is an essential component in any GNSS system. To work efficiently the antenna size should be comparable with the wavelength. Typically, a conventional GNSS receive antenna might measure around half a wavelength (15cm) which is too large for many applications such as man-worn or electronic tagging systems. Smaller GPS antennas are available, but have reduced sensitivity. Also, as alternative GNSS systems such as Galileo become available there is a need to work with services operating on multiple frequencies from a single antenna.

For navigation systems suitable for the installation on either small vehicles or individual soldiers the challenges are to make an affordable antenna with a small physical size and high sensitivity. For antennas worn by humans, exploitation of 'smart' conducting ' textiles that can be integrated into clothing will be an advantage.

This proposal is for a project to investigte highly compact antennas for GNSS applications covering the 1176MHz (GPS L5/ Galileo E5a) to 1575MHz (L1/E1) frequency range. The project will be led by BAE Systems Advanced Technology Centre (ATC) who have over 50 years experience in antenna design, navigation techniques and electromagnetic (EM) simulation. ATC develops technologies for BAE Systems product units (Military Air, Maritime and Land Systems) and so is well placed to bring a military systems perspective, environmental qualification and exploitation route to the GNSS solution. MoD is currently funding ATC to design both wideband antennas and antennas manufactured using conducting textiles. ATC will be supported by Liverpool University (LU) who are one of the leading Universities in the UK for innovative research into novel antennas, electronics and measurement techniques. This proposal is for Phase 1 which will assess novel, highly compact antennas and techniques for manufacture. Recent research at LU has demonstrated a compact (50mm x 50mm x 2mm) antenna design which receives circular polarisation over the desired three frequency bands (1176, 1227 and 1575MHz) with low rejected power (VSWR<1.5). This design, which is described in this proposal and is subject to a patent application, achieves a performance close to that required by SBRI. However, Phase 1 will investigate further size reduction, use of alternative materials and sensitivity of the design to near by materials.
Following Phase 1, a prototype antenna will be built and demonstrated in Phase 2 which is outlined in this proposal.