On 5/10/2013 9:29 AM, George Dubovsky wrote:
3. "RF ground system" is a perfectly good term and is accepted and
understood in the rf design community.
I strongly disagree -- it has led to HUGE misunderstandings and TERRIBLE
errors in the construction of equipment that are so widespread that they
are accepted as the only way to do it, and are a major cause of hum,
buzz, and RFI. It causes people to think that ground rods are a desired
part of an antenna system.
It also causes people to think that separate grounds for RF, audio, and
power are somehow a good idea. And it causes people to view a connection
to earth as a cure for all ills, including, but not limited to, RFI,
TVI, and antenna performance. And that the earth is somehow a sink into
which noise and RFI can be poured.
What REALLY matters to the RF design community is keeping track of where
the current flows, and that means ALL the current -- DC, audio, and RF
-- on every cable. Henry Ott says this quite poetically when he speaks
of "the half of the schematic hidden behind the ground symbol." Is the
reference PCB layer under microstrip complete, or is it broken for a
extra trace that wouldn't fit (or was forgotten) on the main layer?
Does the cable shield go directly to the shielding enclosure, or does it
go to a circuit trace to create a "Pin One Problem" YOU may not have
made these errors, but the vast majority of equipment is built with
these faults.
If you re-read my post, you will see that I wasn't objecting to the
connection of the common point of a radial system to a ground rod.
73, Jim K9YC
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