HF Ionospheric Sounding

High frequency (HF, 2-30 MHz) signals can be reflected by the ionosphere, typically at altitudes of around 250 km, enabling propagation well beyond the horizon to distances of 500-3000 km. This property makes HF systems powerful tools for remote sensing of the near-Earth environment and for monitoring large regions of the ionosphere.

Conventional ionospheric sounders and imagers provide valuable information, but they face limitations. Traditional approaches often only resolve dynamics along a single line of sight, which restricts their ability to capture the full velocity vector of plasma structures. They also encounter challenges when attempting to observe multiple fast-moving features simultaneously or to disentangle low-velocity structures from strong background signals.

To address these constraints, we are developing a relocatable, mobile, ionospheric sounding system. The design departs from conventional configurations by employing a large transmitting antenna array paired with a compact receiving array. This offers three key advantages:

1. Enhanced capability to resolve slow-moving ionospheric features even in the presence of strong clutter.
2. The ability to determine full vector motion, not just along a single viewing axis, across a wide spatial region.
3. Continuous “staring” observation of multiple regions of interest simultaneously, rather than sequential scanning.