Ground / Counterpoise

Grounding
the least understood topic
Amateur radio stations have three unique and separate grounding functions;
Electrical (Safety) Ground,
Station (RFI) Ground and
Antenna (Counterpoise) Ground.





Electrical Safety Ground
is a connection to chassis to prevent operator contact with dangerous voltage if electrical power supply insulation fails. This connection provides a return path to trip the circuit breaker.




Station RFI Ground
is a single point at which shack equipment ground lugs are connected together  through a very short, low impedance lead. so any RF that reach the station will be largely shunted to Earth.





Antenna (Counterpoise) Ground
is the other half of the antenna. Normally a wire, one-quarter wavelength long. It does not need to be straight. Placing radials in the sandy soil DEGRADEs effectiveness. A BALUN is needed to isolate to antenna ground from the station ground.




Why you need a good Counterpoise


A vertical quarter-wavelength antenna has two key components in radiation; the vertical and a ground plane are required and equally important. There are numerous articles on ground planes. In this case the radials the better you only get some relief on length again a quarter-wavelength is best. The idea of a good ground plane is to reflect the maximum of your radiated signal, and stop it being absorbed in the ground. It also reflects the received signal into your antenna and improves the low angle pattern for DX. You can't work them, if you can't hear them. Radials of any length are better than none, but ideally a quarter-wavelength. If space is a problem linear loading the ground wires is a backup plan, this works and is better than short radials. Most lots in The Villages are not large enough for this type of installation, but, with some creative thoughts, great things can be achieved. Review the following slides and determine the best layout for your property.

Guidance for your Ground Plane
•    Local soil resistance is high & more than a rod is required
•    Use 16 or more radials but 4 radials 1 foot above ground are better than 30 in the ground
•    Length is more important than Number
•    Cut to ¼ WL for lowest frequency
•    Radials can be “bent” around house if needed
•    Connect radial ends

 DIY Material
•    Copper, Galvanized or Aluminum
•    Cut slit in grass with edger
•    Connect at base of antenna vertical

 Purchased
•    Hidden Dog Fence vendor will charge $150 to $200 for 16 Radials
•    Ground Radial Plate Kit

One thing to  consider before you built a Flagpole

Due to the sandy soil conditions in The Villages it is next to impossible to get a "Typical" performance from in ground radials. If it is possible to have two radials one foot above ground (i.e. in the bushes) are better than 30 in the ground. If above ground is not possible you can see in the figure below an attic dipole will give the same DX results. If you must have a flagpole be sure to design a dedicated counterpoise as part of your flagpole design and placement.


Typical 100W T/R on 40 M shown above with four different antennas


Dipole is less than 20 Feet above ground level
Theory is a computer model perfect ground plane
Sea is a ¼ WL Vertical Antenna measured over Sea Water the best Ground Plane
Typical is a ¼ WL Vertical Antenna measured over ground better than our sandy soil

Antenna Height and Communications Effectiveness
By R Dean Straw. N6BV,  Gerald L. Hall. K1TD


DX openings are few above 15° Elevation, improvements can be realized by;
•    Increasing the height of the antenna
•    Raising the ground plane 1 to 5 Feet above ground
•    Use a Vertical Dipole or J-Pole that do not require Ground Plane, but are 2X, 3X taller
•    Put in 16 (or better 32) Radials if not an attic dipole will be a better DX antenna choice √

Solid Ground Connections are just as important as more radials
•    Bond mechanically and electrically
•    Use anti-corrosion paste
•    Keep dry

For more information on RF Ground Systems Click Here