Dual-Band Spiral Printed Quadrifilar Helical Antenna Miniaturized by Surface and Inner Dielectric Loading

The design and implementation of a spiral-folded printed quadrifilar helical antenna (FPQHA) is presented for a global positioning system (GPS) $L1$ -/ $L2$ -band application. The proposed FPQHA can be miniaturized by inserting dielectric loading inside the helix, covering the radiation elements by the dielectric sealant and turning the radiation elements into the form of parallelogram spirals. The manufactured antenna’s radiation elements are printed on a hollow rod ceramic substrate with a diameter of 12 mm and a height of 24.7 mm. The measurement results of the proposed FPQHA mounting on unmanned platform fit very well with the simulations, which validates the design methods and suggests that the proposed FPQHA is suitable for GPS $L1$ -/ $L2$ -band applications.