Input Impedance Characterization in Deployable Quadrifilar Helix Antennas

This paper presents an input impedance characterization method relying on measured data enabling a design for manufacture and assembly approach in the development of a deployable L-band Quadrifilar Helix Antenna (QHA). A dedicated TRL calibration circuit enables accurate impedance characterization at each port. Multiple measurements were performed to capture the variability of the input impedance due to deployment and manufacturing tolerances. A statistical analysis of the results provided the mean value and variance of the input impedance, used to design the feeding circuit. This method improves the robustness of deployable QHAs, reducing notably the risk of non-compliances in the return loss.