I have an existing fiberglass rocket called Gizmo that is 5 inches in diameter. It is a short stubby rocket. I am procuring a two foot extension of the airframe. This will allow plenty of room for a radio payload. The rocket will split into two pieces at apogee. The upper section will have the nosecone/payload bay and the lower section will have the fins and the motor tube.
For an HF beacon, I envision having enough shock cord between the two sections for a half wave end fed antenna to be strapped to the cord. Say 33 feet for 20 meters. Since the antenna is coiled up in the rocket for assent the transmitter should be off. I may be able to use altimeter electronics to delay turning on the the transmitter until the rocket is at apogee. At apogee an ejection charge will fire to deploy the parachute and the antenna, Apogee may be a couple of thousand feet. The duration of the descent may only be a minute or so. It seems I could use a message like TEST DE N4KGL and be picked up by the Reverse Beacon Network.
At 20 meters the antenna would essentially be a vertical dipole up many wavelengths. It would be omnidirectional and would definitely be in the clear. I suspect the direct wave would be extended. I am not sure how much better it would be than a ground mounted antenna for DX. Perhaps I could have a reference beacon that is ground mounted beacon with a 5 KHz frequency offset.
I would also put a two meter fox transmitter in the rocket to help locate it should it leave the field. Hopefully I can get this going over the next couple of months. I will definitely will let the hams know if they want to try hearing it. It will be launched from the SEARS launch site in Samson, Alabama.
|A Gizmo Launch|
|The original beacon rocket trailing a 33 foot antenna wire. You may see the wire in the photo.|