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A simple method for designing and optimising a multiband printed quadrifilar helix antenna is presented. Using multiple arm techniques, a tri-band antenna working in L-band for GPS applications is realised with a good gain and a good circular polarisation. Measured results are presented to validate the concept.Introduction: The quadrifilar helix antenna (QHA) [1] and more recently the printed quadrifilar helical antenna (PQHA) [2] are usually used in low earth orbit (LEO) satellite communications, handsets of global positioning system receivers and satellite mobiles [3]. The distinguishing features of this antenna are its cardioid pattern, circular polarisation and logical size compared to other antennas. In particular, the cardioid pattern is the favourite pattern for LEO satellite antennas. With the development of GPS and satellite navigation systems, an antenna covering dual-frequency or even triple-frequency is required for more demanding applications. One of the current problems of conventional PQHA is that it is difficult to work at multi-frequency. Several techniques have been described in published work that would extend this antenna's capability to two frequency bands; each of these techniques has some limitations and advantages with respect to size and/or performance [4][5][6][7]. In this Letter, we investigate a novel design method based on multiple arm technique to obtain a multiband PQHA (MB-PQHA) [8]. As an example, a triple-frequency band PQHA is designed. We provide details of the proposed antenna design operating in L-band as well as the experimental results.

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