An amazing article on ground and radio frequencies

The Ground Connection

  Here is an article that will be of great service to you, both in terms   of safety against electrocution and in terms of balancing the   operation of antennas with respect to the ground plane.  
  It has not escaped your notice that professional electricians have this   unfortunate tendency to establish a ground connection (economically) by   simply fixing a ground rod one meter or 1.50 m long in the ground,   preferably as close to the wall as possible.
  Gross error! Never install a ground rod in a   backfill area. That is, in the area that surrounds the periphery of the   construction and hides the foundations.

Indeed, the backfill includes all construction waste (pieces   of broken breeze blocks, broken bricks, pebbles, stony soil, and all   other debris that contractors want to get rid of).
  You will therefore easily understand that a single ground rod planted in a   backfill area is absolutely to be avoided because in such terrain (hostile to   this ground connection due to its poor natural conductivity), the ground connection   is practically of no help, as it presents a resistance   much too high (measured with an E.D.F. electronic ohmmeter).  
 
  For radio transmitting and receiving installations, this can   even lead to HF current returns, poorly radiated by the   antennas, so be careful, because this lost energy quickly turns   into heat and can seriously damage your equipment.  

  So, to avoid all these pitfalls that await us, what should we   consider to create a ground connection worthy of the name and producing all   the effects we are looking for?  

        

 
• It is necessary to move away from this backfill area and by means of a small trench of 40 X 40 cm dug perpendicularly to the wall of your station, you must go and find the good topsoil, the one that has not suffered from the construction of your property or dwelling.  
 
• Once this good topsoil is discovered, you dig another trench (at the end of the first one). It can be 1x1 m and cubic or rectangular in shape if you want to put a larger plate.  
 
• You prepare these two trenches by sprinkling them with several packets of coarse salt (sold by the kg).  
 
•   You obtain twisted copper wire with a diameter of 10 mm,   not sheathed in plastic, it must be bare.  
 
•   You buy (or find in your personal stock) a plate   called 'Ground Terminal Block' which you will fix to the wall with two screws on   anchors and you install it as close to the ground as possible, where the   yellow and green cable must penetrate to reach your radio station. This   terminal block is easily identifiable because it consists of two terminals in   steatite (or white porcelain) with fixing bolts and a jumper   metal short-circuit, to put the ground connection in service, or   out of service.  
•   Extend your thick, bare copper wire into the trench   leading to the good topsoil layer. But be careful: do not   lay the cable straight; it must be laid in a zig-zag pattern, as this   will help improve conductivity with respect to the ground.
•   Install the metal plate of 1 m X 1 m or even larger, at the bottom of the trench, on the spread salt. It can be a plate of already rusted steel sheet, which must not be cleaned. It should be 10 to 15 mm thick. Thicker will not hurt, and larger neither, 1 x 2 m, quite the contrary ...
•   Fixing the copper cable to the plate. One can easily find in some large hardware stores fixing systems designed for this purpose. Simply drill a hole of adequate diameter in the thick sheet (having taken care to clean this sheet just at the point where the copper cable is attached). Assemble everything and tighten securely. Coat this fixing with silicone grease to preserve the contact from moisture, so that conduction is always perfect and the contact resistance as low as possible. At the limit, a good solder joint will do perfectly.  
 
• Sprinkle coarse salt again on top of the metal plate (steel - copper - bronze - never aluminum) and cover it with the topsoil extracted from the burial hole, taking care not to let any impurities such as pebbles, etc., pass through.  
 
•   Flood the location of the metal plate hole with water so that the coarse salt produces its corrosion effect, and only stop watering when the water overflows from the hole.  
 
• - fill the trench that allowed you to get out of the backfill area, with good topsoil and also flood it with your hose to also facilitate the corrosion of the copper cable there.
  NOTE: This copper cable, if you maintain good relations with the E.D.F. (French national electricity provider) services, can be provided to you by employees, coming from dismantling high-voltage lines. This is worth considering, as it is cheaper and sometimes free!!!  
•   All that remains is to fix the copper cable coming out of the trench to the ground terminal block. Solder an appropriate lug with tin and screw it onto the bottom terminal.  
 
• - your external ground connection is installed; however, I will give you a little tip that will allow you, in summer and during the dry season, to keep your ground connection properly moistened. With a crowbar, make a small hole right in the middle of the trench where the metal plate is buried.
  Slide in a 1.50 m PVC pipe with the end cut at an angle. Insert the neck of a transparent plastic water bottle into it, remove the bottom with a cutter, and fill it with water regularly. Your ground connection will always be in perfect working order. During severe droughts, remove the bottle that serves as a funnel and put the hose in it. When water comes out of the hole, you stop and repeat this operation whenever necessary.  
 
• - installation of the ground connection inside the radio station:
  • - use a yellow and green copper cable specifically intended for the installation of internal ground connection circuits. The diameter will be 10 to 15 mm. Bring it behind your equipment.
  • - fix a ground terminal block to the wall and place the end of the stripped yellow and green cable on it. Using a system of semi-rigid copper wire jumpers of 8 to 10/10th, connect all the wire clamping terminals together.
    
  • - with flexible yellow and green copper cable of 4/6 mm diameter, connect each device to the terminal block of your radio station according to the ""star"" system. Do not connect the devices to each other. They will be connected via the ground connection and the ""star"" system.
  • - that's it, your station works wonderfully, no more RF feedback that stings your fingertips, no more QRM (interference) on TV or broadcast listeners. Why??? Because you knew how to install an excellent ground connection, clearly superior to those usually installed by professionals, who only seek to save time, but quality and efficiency are certainly not their primary objectives.
  • - When you have the opportunity, have the resistance of your ground connection measured by E.D.F. employees voluntarily and with their new device, which is no longer the old magneto ohmmeter, but a state-of-the-art tellurometer. If it is between 1 and 5 Ω, it is practically perfect; if it measures between 6 and 10 Ω, it is average; if it shows a resistance greater than 10 Ω, it needs to be improved (redig a trench and put in a new metal plate connected to the first one). In any case, you must achieve the lowest possible resistance. E.D.F. accepts resistances of 30 Ω for grounding the neutral conductors of their installations.