Compact Printed Quadrifilar Helical Antenna With Iso-Flux-Shaped Pattern and High Cross-Polarization Discrimination

In this letter, a technique for the miniaturization of conventional printed quadrifilar helical antennas using simple sinusoidal profiles is described and supported by experimental results. The challenge is to reduce the size of the antenna while maintaining iso-flux radiation patterns and high cross-polarization discrimination. The miniaturization design approach simulation and measurement results are given in the case of a specific design of L-band telemetry link antenna for meteorological stratospheric balloon payloads, but the achieved results can be extended to any quadrifilar helical antenna with shaped pattern. Size reduction close to 50% is reached while preserving major radiation pattern characteristics and good axial-ratio performance over a wide angular range.