I have my shack on the second floor, about 8 meters above ground. I am
going
to use a dipole antenna for 20M
Should I use the water pipe system as ground, or should I use a thick wire
on the housewall down to a ground rod?
I fear that the wire down to the ground rod may emit unwanted RF (have
read
that somewhere).

======================================

One of the advantages of a dipole antenna is that it doesn't need a ground
connection. There's nowhere to connect one.

The transmtter does need a ground and it usually obtains one from the
domestic 110-volt power socket.

But a much better ground can be obtained from the nearest domestic metal
water pipe or central heating system which eventually finds its way to the
incoming water main.

Two separate well-spaced ground connections, running in different directions
from the transmiter to different parts of the plumbing system are better
still. There is usually a threaded bolt with a wing nut at the rear of the
transmitter for connecting to ground wires.

A wire down the wall to a single ground rod makes a very poor ground. It is
worse than the connection to the 110-volt power socket. The rod is no
better than a shallow buried wire of about the same length. It is only of
use when there's nothing else available.

Grounding wires need be no larger than 16 or 12 gauge. Think in terms of
mechanical durability and reliability.

All wires in the vicinity of a transmitting antenna pick up and re-radiate
energy or transfer it somewhere else. It is of low level, usually
imperceptible and nothing to worry about.

Only when connected directly to an antenna to form part of the radiating
system will relatively large amounts of power find its way along wires to
where its not wanted. Something is usually seriously wrong if you should get
small harmless burns on the lips when using the microphone with a Tx power
of 100 watts or less.

There are a score of different ways in which things can happen. All are
curable. Most likely you will never be afflicted. No need to do anything
until something actually occurs.

It's very rare for earth wires to re-radiate anything that is harmful or
interferes with anything or is even detectable. Since 99 percent of
radiation comes from the antenna that's where most of the interference in or
around your house originates - if you should get any.
----
Reg