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Saucer Vertical Performance on 30 Meters

saucer vertical performance

My flying saucer vertical performance turned out okay on 30 meters. On 80 meters, not so much. It tunes but is quite inefficient.

So, after all the design and construction, it was time for me to actually test saucer vertical performance. Remember, I have built a very short 8 foot antenna with a couple of resonators at the top. Two 24 foot radials stretch out from the base, lying on the ground.

Achieving resonance and a decent SWR match on 10.1 MHz was straightforward. My first dip at 9.8 MHz was attributable to the tuned radials. My second dip to encompass the 30 meter ham band was derived from the saucer resonator. On the right above, you can see the reactance curve hit zero at 10.1 MHz. Feed impedance is 31Ω  with an overall in-band SWR of 1.3:1.

Since the electrical length of an 8 foot pipe at this frequency is only 30° (versus 90º for a quarter-wave), I know this will be a weak antenna. My estimate is that the resonator brings the radiation resistance RRAD up from 2 Ω to around 6 Ω.

With total impedance of 31 Ω resistive, and accounting for a few ohms loss in the inductor and connections, I figure my ground loss resistance is around 20 Ω. Crunching the numbers, I get an efficiency of around 20%. This means I probably have 12 dB of lost signal to heat when I transmit. Overall, receive performance is about 2 S units down from a full size antenna.

But, it works. I can hear and work lots of CW and FT8 stations, mostly from within 3,000 kilometers, but a few Europeans as well.

Saucer Vertical Performance on 80 Meters

My 80 meter resonator gives me a pronounced dip on 3.85 MHz but not enough. SWR remains well above 5:1 and the antenna remains quite capacitive. Given that my 8 foot pipe is only 12º electrical on this band, I should not be surprised. Perhaps I need to do a better job winding the saucer coil.

I did notice some interaction when both saucer resonators were installed, but not much.

Overall, for receiving, my wideband magnetic loops seriously outperform the vertical on 80 meters, and are about par on 30 meters. If I chose to do so, I could use the vertical on 30 meters for regular operations. But one thing I have discovered is a lack of activity on 30 meters in my part of the world.

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