The idea was to send GPS data from the rocket to the ground station at 433 MHz using a Lo Ra transmitter - mainly to help locate it once it lands and also to provide in-flight telemetry.
I have a similar transceiver on the ground - but lack an appropriate antenna design. I have had it suggested that a Circular Polarised Antenna for the mobile ground station would beneficial, but I have no idea of what form this would take - either to buy or construct one from scratch.