|If Wspr is a beacon mode
then I can't help but think a beacon should operate in all
directions. On four metres, traditionally, horizontal
antennas have been used, usually Yagi types. I don't think
there is much chance of this changing. So how to radiate a
360 degree horizontal signal? It would also be good to do
this with gain by preventing radiation skyward.
Back in 2010 I tried a turnstile. However, due to lack of activity I never really reached a conclusion as to its effectiveness, I did know though that it had no gain. I am always able to hear GB3BUX and I noted it uses a double turnstile. Reading around on the net I came across G8SEQ's page . It looked to be the answer to my needs.
Over the last thirty odd years I have built many different antennas. One thing that seems to be a constant is that prototypes often work better than the finished, sealed and aesthetically pleasing final version. So although it was built in a couple of hours and has coax dangling like ivy I wasn't too concerned that the lash up approach would be detrimental to its performance.
Happily on the very first transmission the signal was spotted by M0NKA (Thanks Chris!) I could hardly believe it. In the following two days of testing spots came in well from both North and South simultaneously. This did not happen (unsurprisingly) with my yagi antenna.
I am about to tidy up the antenna and create the final version. Here's hoping the final version works just as well.
I am still not convinced by this antenna. Perhaps the stations who spot my signal are doing most of the work with their higher gain yagi antennas?
Time will tell ...
Version 2 with phasing coax inside the tube. Neater, but the swr rose very slightly. Note the coiled matching and phasing section this might also have changed things. So much for being tidy.
The final version sited at 9m agl. The top elements are therefore at around 11m. It retained its docile characteristics.