P-158 DataVault II: Directional Antenna Construction

The DataVault Project that I am working on is intended to store data for a long period of time. Since the location of the DataVault could easily have been lost or forgotten over the years, the device will need some kind of radio beacon or transponder to allow it to be located.

I intend to use a simple long-range transmitter for this, with a directional antenna. The device would be programmed to emit a pulse from the transmitter at regular intervals, after a certain period of time has elapsed.

I have wired up an antenna that I built for a previous project to a transmitter and receiver, in order to evaluate the effectiveness of it’s direction finding abilities. The antenna is a Yagi, built for 433 MHZ.

This antenna did not function particularly well as a directional antenna in the previous project it was used in. I believe this was due to poor impedance matching between the antenna and the cable. I have shortened the cable as much as possible to try to alleviate this, hopefully it will have at least basic direction finding abilities now.