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Originally Posted by Doug
But with static, and lets remember Radio Astronomy listens to static, not ET phoning home (sorry Seti  ). Any simple low gain antenna will be like looking at the sky through a piece of ground glass. You can see that there is light if the sun or moon is up, but have little idea of direction or anything else about that light. |
I think this is a very important point to realise before making any significant investment in this project.
How can you know the source of the noise you are receiving unless it can be verified by steering the antenna toward and away from the source?
The antenna design on the first page of this thread looks like a directional design, but its physical size looks to be very small for an antenna designed for 21MHz, and hence will have a small
capture area. This means a low efficiency at plucking signal from the air and you would find that a simple dipole will pick up much more signal, but then a dipole isnt steerable
Antennas with usable directionality and gain become much more managable at higher frequencies due to their smaller size.