A Frequency-Reconfigurable Single-port Handset Antenna for GEO and LEO Satellite Communications

This paper presents a single-port handheld terminal antenna for geostationary orbit (GEO) satellite communication at S-band (1.98-2.01GHz, 2.17-2.2GHz) and low-earth orbit (LEO) satellite communication at L-band (1.518-1.525GHz, 1.668-1.675GHz) based on reconfigurable technique. The quadrifilar helix antenna (QHA) is designed with two sets of helices of different pitches integrated into a single structure. The lower QHA features a smaller pitch, while the upper QHA has a larger pitch. These helices are stacked and wound around the same dielectric support cylinder, forming a compact and efficient antenna configuration. The lower and upper helices are interconnected using PIN diodes, enabling reconfigurable operation of the proposed QHA. By controlling the on/off states of the radiating arms through the PIN diodes, the antenna can switch between GEO and LEO satellite communication modes seamlessly. The innovation lies in sharing the feed network for both the DC control signal of the PIN diodes and the RF signal, which effectively eliminates the need for additional DC bias lines, thereby minimizing the impact of the DC control circuit on the antenna's radiation performance. Additionally, a miniaturized broadband quad-phase power dividing network based on a multilayer structure of wide-edge coupled striplines is designed and implemented at the base of the QHA, which enables circular polarization at both bands. The measured results show that good impedance matching (S₁₁<-15dB) and axial ratio (AR<0.5dB) are obtained. Additionally the gain is greater than -3dBi within ±80° beam range at L-band and 1dBi within ±45° beam range at S-band, respectively. The proposed QHA is a good candidate for dual-mode satellite communications.