The bi-stable deployable quadrifilar helix antenna passively reconfigures its radiation characteristics in terms of pattern and polarization. | Image courtesy of Reconfigurable & Active Structures ...

[Mark] had his eyes on the nice quadrifilar helical antenna used by the Vaisla R92 radiosonde’s GPS receiver, with the aim of repurposing them. He had a lot of components to remove while still ...

The antenna normally operates in a vertical configuration. It looks like it might be simple to make some version of this without anything exotic. Let us know if you try! Helical antennas aren’t ...