[TowerTalk] Fwd: Fwd: Shielded shack

[Jim Lux]

On 9/29/13 9:14 PM, Roger (K8RI) on TT wrote:
> On 9/29/2013 8:36 PM, Hans Hammarquist wrote:
>> Yes Jim, the "single point" is not really a single point. In my case
>> it is a single, conducting panel that has feed-through coax connectors
>> and surge protections for all other wires coming through the panel. I
>> plan to use gas discharge for signaling and MOX for power (Done that
>> before with good result. Yes, it was tested with real lightnings.).
>> The panel will be connected all around its perimeter  to the shield.
>
> Metal window screen works well into the GHz range

For lower frequencies, you need thicker material for good shielding: the 
skin depth is bigger.

To be a good shield, it needs to be at least 5 skin depths thick (that 
makes the field on the "inside" exp(-5) that of the outside (about 40dB 
down)

> It'd be a bit more pricey than foil.  With foil, I'd use the heavier
> stuff. It more effective and not as fragile as the stuff we normally
> have in the kitchen.
>
> My shop / ham shack is completely lined with bonded barn metal.

Steel is a good shielding material: the high permeability makes the skin 
depth small.  It works well for the same reason that winding a choke on 
a powdered metal or ferrite core works well.