No1PC: RF and Station Ground References

A Collection of Essential RF and Station Ground and Protection Data

On this page are links to additional on-site and off-site references providing some theory, practical, and data results from a variety of electrical, broadcast and commercial radio experts.

Station Grounding References

It is amazing what we didn't know about grounding, and need to...

#1 - GROUND implies EARTH.

#2 - GROUND is NOT counterpoise or radials. There is a reason that specific dedicated radial wires are recommended vs. ground conduction (which sucks.)

#3 - STATION ground is NOT part of the RF/antenna system

#4 - GROUND is NOT the electrical/safety/green-wire of commercial/residential electrical systems - those are NOT designed to carry current or dissipate energy.

#5 - GROUND, or RF GROUND or STATION ground is intended to be THE zero- or lowest-impedance point ALL equipment should be tied toto reduce/eliminate potential difference (RF, AC, DC) between different station equipment and antennas.

#6 - EACH piece of equipment should be connected by a single discrete unique conductor to THE SINGLE RF/STATION ground point. NOT daisy-chained or looped between chassis/shield to other equipment. HOME RUNS folks!

#7 - THE ground point is incapable of and therefore NOT meant to dissipate or absorb a lightning strike. Lightning involves millions of volts and amps that cannot possibly be accommodated by any practical human-provided current-sink.

#8 - At best THE ground point and grounding equipment can provide a point to sink voltage differences between chassis, eliminate the differences of inter-chassis potentials and coupling, inhibit re-radiation of stray currents to other devices, and help keep AC/DC/RF currents off the AC-mains conductors and safety ground.

#9 - THE ground is NOT part of the RF/antenna system

#10 - Did you know typical earth ground resistance is above 200 ohms? That is most certainly NOT the zero-ohm impedance needed for proper radials/counterpoise for verticals.

The first three links below provide considerable text and helpful graphics. Each article contains essentially the same/similar information which also corresponds to some degree with what is in-practice, recommended and even necessary in "RF shops" from small to large broadcast and two-way installations.

Unfortunately the National Electrical Code, NFPA and other U.S. standards bodies do not have a spec or code requirement for RF installations, as RF is still fairly specialized and isolated (as it should be) from A.C.-mains power concerns.

The common thread through all of these is:

* the goal is to ensure any and all external/stray (not intentional as-in coax or twin-lead) RF is routed as directly as possible to EARTH. Not some long meandering inadequate 14 gauge electrical wire, or conduit looped through a power box.

* Power mains safety ground is NOT a good RF ground

* Your RF system should have its own stout, brute force, highly effective EARTH GROUND

* Each individual piece of RF station equipment, from power supplies to rotor control to antenna switch to receiver, transmitter and amplifier, tower(s) and antenna(s)/feedline should have their own individual dedicated ground wire running directly to the single unique RF ground rod/bus.

* The National Electrical Code, and where adopted, requires exterior antennas and structures to be grounded.

A few pictures of lightning damage.

How lightning protection systems work
NOT incompatible with required station/utility ground systems... so integrate.

Video about lightning protection systems
When he mentions ground rods... refer to Mike Holt's video below, and bond all of them together...

W. Reeve Article on NEC Implementation for Amateur Radio

SeaPac Presentation on NEC and Amateur Radio

Mike Holt's Video Collection
The Grounding... videos, especially resistance testing (below), are very telling!

Mike Holt's Ground Resistance Testing

Soil Resistance

Soil and Lightning

No1PC: Station Grounding Diagrams

W8JI - Station Grounding

N7DY - Station Grounding

MIL-STD-188-124B

KF6GDJ - Station Grounding

Commercial Telecom Paper

A very good paper on soil resistance - must read.

Motorola R56 at Repeater-Builder

Polyphaser - Solutions for Comm Sites

Grounding versus Counterpoise

NO1PC As-Built Single-Point Station Ground

 

 

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