[R-390] Polyphaser Documents

[Sheldon Daitch]

Roy,

When we do concrete with rebar in and around active towers, we
try to do a lot of rebar bonding so the rebar is at ground potential.

Some of this grounding includes tack welding every rebar crossing
especially if the concrete is very close to any of the high power antenna
systems.  We also bring out at several points, ground ties from the rebar
inside the concrete to the regular grounding, for HF, generally ground
rods driven into the ground, or in the case of MW arrays, to the 120 to
240 ground radials around the base of each tower.

In general, we try to bond everything metal to ground.  This is particularly
important in a high power RF environment where any metal of significant
size not ground tends to float, and can be hot from an RF perspective.

This includes things most people never think of, such as placing flexible
braid across door hinges of metal door sets, so the doors do not
become RF hot and shock people when they touch an ungrounded
metal door.


73
sheldon

Roy Morgan wrote:
>> ..., I have been
>> reading the various technical notes offered at the Polyphaser site:
>>
>> http://www.polyphaser.com/technical_notes.aspx
>>     
>
> One of these documents, "Ufer and  Tower Grounding",  puzzled me:
> What does Ufer mean, I wondered.    The Polyphaser author made no  
> mention of what Ufer means.
>
> I found this explanation:
>
> Ufer Ground is an electrical earth grounding method named after  
> Herbert G. Ufer, who developed the technique during World War II in  
> Arizona. A synonymous term is "concrete encased ground electrode". It  
> is installed by connecting the ground wire to the steel reinforcement  
> bars in foundation concrete, or by embedding a length of wire in the  
> foundation near the bottom of the concrete.
>
> So, Now I have some idea.
>
> (And that document shows no cutoff of bottom lines I wondered about  
> earlier.)
>
> Roy
>
>
>