Re: Mesh size for 10GHz

Dom Baines M1KTA
 

Thanks all for collective info looks like a single layer of the larger mesh should be fine.

Anyway where did the 'rule of thumb' bit come from that is what taxes/puzzles me most ... Ive seen it several times but what is the underneath reasoning/calculation? How much loss might I expect in that direction?
72
Dom
M1KTA

On Saturday, 19 October 2019, 19:48:35 BST, KENT BRITAIN <WA5VJB@...> wrote:


30/4 would be more like 7-8 mm and the usual 'Rule-of-Thumb' is 1/10 wavelength or 3 mm.

Kent

On Saturday, October 19, 2019, 1:37:49 PM CDT, John E. Beech <john@...> wrote:


I don't think it will make any difference. The criterium for a mesh dish is that the mesh size must be smaller than a quarter wavelength at the frequency in use ie < 15 mm for 10 GHz.

de John G8SEQ

>  -------Original Message-------
>  From: Dom Baines M1KTA via Groups.Io <dombaines=yahoo.com@groups.io>
>  To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
>  Subject: [UKMicrowaves] Mesh size for 10GHz
>  Sent: Oct 19 '19 18:27

>  Was suggested ask here so here goes.

>  Bit of a rookie so might be a daft question:

>  If using a mesh reflector for a dish with size 2.5mm x 4.5mm does
>  this mean it will be fine in one plane but might be very lossy in the
>  other at 10Hz as 1/10th is c3.0mm. But by how much?
>  Should I cross the mesh so the centre (opposite prime focus) at least
>  has no opening larger than 2.5mm ?

>  Solid dish had some wind-age issues and moved (understatement) so got
>  to rethink.

>  72

>  Dom
>  M1KTA




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