[HCARC] Grounding Straps For Safety Ground

[Kerry Sandstrom]

Gary,

I use copper braid because it is flexible and easier to use than solid 
copper wire.  As you probably recall, RF currents stay on the surface of a 
conductor and not the interior.  Braid has a lot more surface area than a 
solid copper wire.  I use braid for grounds as well as for wiring in RF 
things like antenna tuners and amplifiers.

I saw Jerry's post.  As he kind of said, as an apartment dweller he has to 
make compromises and his long wire with counterpoise and now the TAK antenna 
work OK for him.  Counterpoise is kind of a new word.  I never used to hear 
it.  Basically it seems to me that you have a bunch of metal that you use to 
establish a ground plane much as the 3-4 radials on a ground plane antenna 
establish a ground reference for the vertical radiator of a ground plane 
antenna.

Theren are other ways to do it.  Perhaps you've seen the trailing wire 
antennas used for VLF on the airborne command post and TACAMO aircraft. 
There are actually two wires of different lengths used.  The transmitter 
feeds the two wires through an impedance matching network (antenna tuner). 
The wires are quite different lengths.  It works.  It is also possible to 
end feed a half wave wire with open wire line and an impedance matching 
network.  Neither of these antennasd require an RF ground.

Jerry also says he uses the building ground for his DC ground.  I interpret 
that to mean he is using the building ground as the power safety ground 
which is appropriate.

So, to summarize, there are two separate grounds, a safety ground for the AC 
power and an RF ground for the antenna.  Many types of antennas such as 
ground planes, dipoles, Yagis, log -periodic dipole arrays, etc don't 
require an RF ground.  Other antennas such as verticals, invertede-L's, 
random long wires, etc require some kind of an RF ground.  An 8-ft ground 
rod is not an RF ground.  An RF ground is a field of conductors covering a 
large area.  You need a safety ground in your shack.  You don't need an RF 
ground in your shack (Note: this is convenient since it is difficult to get 
a good RF ground in your shack!).  You do need an RF ground at the feed 
point of some but not all antennas.  Antennas that "look like" a dipole 
usually don't need an RF ground.  Antennas that "look like" a vertical do. 
Be sure you understand what kind of antenna you are planning on using and if 
an RF ground is required by that antenna, be sure you have one.  Don't be 
fooled by antenna manufacturers who use unusual words to describe their 
antennas.

Have fun,

Kerry