15-meter EME? Maybe!
As of two weeks ago, ES5TV has what is one of the largest 15 meter antennas in the world.
A 70m tower built by 4O3A supports eight 5-element, 15-meter Yagis configured as four pairs. The Yagis are Optibeam OB5-15′s separated by 12 meters horizontally. The heights of the antenna pairs are 64, 50, 36 and 22 meters.
From Tonno ES5TV:
“Modeling shows ca 16 dbd free space gain and almost 24 dbi gain at 4 degrees over real ground. Beamwidth is less than 30 degrees. Testing has been so far limited but the results confirm exactly the modelling results. Pattern measured with signal generator and SDR was almost identical to what the computer suggests and signal levels drop ca 12 db when antenna is 20 degrees off and already 20 db when 25 degrees off the correct direction. There is huge -50db+ null at 90 degrees confirmed with real measurements (!) and ca -20-30 db signal drop on the other directions.
First comparisons with my best antenna so far (4 high tribander stack) show ca 10 db advantage to US when pointed right. That is huge of course. At the same time east coast and west coast can’t be covered with one direction.
The stack will have phase switching capability which allows any pair of the 4 to be switched out of phase to change the radiation angle. Pre-configured steps are 4, 7, 10, 15, 30 degrees while maintaining most of the gain as all antennas are always connected. The phase switching is not yet connected but will be very interesting to see the results and to get some real insights into how the different angles play.
We briefly tried to hear the moonbounce when the moon was on horizon but did not succeed yet. But 15m was wide open and signals probably did not penetrate the ionosphere. I still hope to be able to complete some EME QSOs with the stack.”
Photos of the entire project from beginning to end can be seen here.
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Themocracy
Yeah, you guys and your beams :) Very cool John thanks for sharing.
I wish mine was comparable…!
[...] rêver, mais juste rêver. Je veux dire par là que ce n’est pas un objectif, juste un songe. AE5X nous présente la nouvelle antenne pour le 15 mètres de ES5TV. Elle a été conçue par 4O3A. Depuis deux semaines Tonno peut se targuer d’avoir une des [...]