A Comprehensive Method for Quadrifilar Helix Antenna Miniaturization

A compact, miniatueized, wideband quadrifilar helix antenna (QHA) is presented in this article. The proposed QHA offers the dual benefit of a substantially reduced axial length over existing miniaturized designs and a reasonable operating bandwidth. First, by loading the hollow dielectric rod, folding the arms, employing different-width arms, and introducing a gap in the arms to realize antenna miniaturization. Second, adjusting the width and height of the gap to broad the impedance bandwidth. Moreover, a compact two-stage Wilkinson power divider is designed, which achieves sequential phase excitation of (Formula presented.), and (Formula presented.) for the helical arms by incorporating (Formula presented.) and (Formula presented.) phase delay lines in the transmission path. Finally, a compact and reasonable wideband QHA is simulated and fabricated. The measured results agree well with simulation. It is miniaturized ((Formula presented.) axial height) and wide impendance bandwidth (FBW=16%). Additionally, it exhibits a peak realized gain of 5.38 dB and excellent circularly polarized performance.