John Markham skrev 2012-01-19 06:49:
On Jan 16, 10:56 pm, Ben / wrote:
Hello!

I'm planning to build a parabolic reflector using aluminium net.

The kind of net i found is just a weave of aluminium threads, no
connnection between the threads. Is this going to reduce the performance
of the reflector?

The net is built of 0.4 mm thread and the hole size is 1.5 * 1.5 mm.
I'm planning to use the reflector on the 23 cm band.

73
Ben / SM0KBW

If it helps, I recall a long-ago rule for perforated and mesh
satellite dishes. The hole diameter could be up to one-tenth
wavelength and the reflector surface would still appear solid to the
EM waves. I had a 3m mesh dish for 4 Ghz c-band TV. It consisted of
twelve unconnected panels.


Yes, those rules do trigger something in my brail too

I'd say try it.

From my imagination: If you were to set up a normal VSWR test with
your 23 cm gear and move a section of the mesh toward the antenna,
you'd know somewhat whether the mesh is a reflector or is RF-
transparent. Compare the VSWR change to a corresponding test using
solid material. Just a thought from my fertile brain (with no mention
of what kind of fertilizer).


Of course, you right, empirical is certainly a good way to decide if the
net is good enough. The secret fertilizer you use seems to work

73
Ben / SM0KBW