Who would have thought it, all that messing around with antennas finally paid off. Here is a the sync antenna we rigged up. Our receiver and transmitter need to synchronised, there are several ways to do that and for this job we are using radio sync, so we required an antenna. Initially we had the antenna standing on the ground, but this only gave us about 200m range, which wasn't enough. We searched around and found a big metal water pipe in a scrap pile and rigged it up with some wire to lift the antenna about 12 feet off the ground. We boosted our range to about 800m.