[TowerTalk] RF on stainless steel

Red RedHaines at centurytel.net
Mon Jun 12 16:02:35 EDT 2006

Any of the stainless steel alloys are suitable for grounding an antenna 
element to the boom to prevent arcing.  Moderately high impedance won't 
prevent them from limiting the voltage difference between the element 
and the boom to less than the voltage needed to initiate an arc or even 
a corona discharge.     Half the energy of a lightning strike is below 
one MHz and half is at higher frequency. 

However, the resistance of some stainless steel alloys, especially at 
the higher RF frequencies, may cause some loss when the objective is to 
carry part of the antenna current.  While skin effect won't prevent a SS 
strap from effectively grounding the element to the boom as far as 
lightning is concerned, it will cause some loss of 160 meter and 80 
meter signals (or higher).

Skin effect depends upon frequency and the permeability of the metal.  
Higher frequency limits the depth of current and increases resistance.  
Higher permeability also limits the depth of current and increases 

Some stainless steel alloys are non-magnetic and thus their skin effect 
is less pronounced than that of the magnetic alloys.

The skin effect is much more serious in conductors intended to limit 
lightning potential for the purposes of protecting equipment in the ham 
station, where an ideal is to approach zero impedance.  While any 
stainless steel strap may prevent arcing, some are definitely undesired 
in applications where their purpose is to protect equipment.

73 de WOØW

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