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Deep Earth ground

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Deep Earth ground

I forget who suggested it, but today I ran a radial from the ground rod under the Procaster, about 120 feet and attached it to my well. The well pipe is something like 300 - 400  feet deep. When the house was built in 2006 the contractor told me that the well had to go either 394' or 494' to hit water. Our well has never run dry and we have no water softener or water filter on it, but many people have told us that it is the best water that they have ever tasted. I agree. Our property is about 150-200 ft. above the street and above the Brandywine which runs parallel to our street. It has made a significant improvement to the Procaster's reach.  It may be subjective but from driving around I'd say it's about a 5-10% improvement. I have not re-tuned the antenna yet but I'd expect that will help a little more. 

As An Experiment

It could be that the long radial by itself is increasing your range.  How about disconnecting the radial from the well and noting if anything changes.

Neil

 

Deep Earth ground

Neil, That might be part of it but last week I installed an additional 5 radials about 100' long (I already had (20) 30-foot long radials) and while I noticed a very slight improvement from those 5 new radials not nearly as much improvement with this one. I'd consider disconnecting it from the well except that I soldered it on and don't want to have to re-do that.

Jim

Jim Henry HBR Radio 1610, serving Honey Brook, PA. and NW Chester County.

To Jim

What a great accomplishment

putting all of those wires down.

Brooce, Part 15 Hartford

NOISE AND STATIC RADIO

Buried R-F Grounds for Monopoles

Following are some comments relating to the use of buried r-f grounds consisting of conductors used with some Part 15 AM monopole transmit antenna systems.  They are based on years of studying antenna engineering textbooks and other published technical papers, and user experience.  Documentation of such comments can be provided on request.

EARTH CURRENTS

The function of a buried r-f ground used with a transmit monopole is to provide a path of low resistance for the r-f currents induced in the earth by radiation from the monopole to return to the system source (the transmitter).  The r-f current flowing along the monopole is the sum of the r-f current gathered by the buried conductors and connected to the r-f ground terminal of the transmitter.  The sum of the r-f current flowing on all of the unburied conductors of a monopole antenna system are responsible for all of the useful r-f radiation from that antenna system. 

This is the reason why the net r-f resistance of those buried conductors should be as close to zero ohms as possible/practical.

For maximum radiation efficiency of a vertical monopole using buried conductors, all of those earth currents existing within 1/2 wavelength* of the base of the monopole need to be collected by the buried conductors. Earth currents existing beyond that radius do not contribute to the useful e-m fields first radiated by that monopole.

For these reasons it is important that the physical common point of those buried conductors is located directly under the base of the monopole, itself.  If it is offset from this, then the r-f currents flowing in the earth within 1/2 wavelength of the base of the monople must travel a longer path through the (lossy) earth to reach those conductors.  This reduces the radiation efficiency of that antenna system.

SKIN EFFECT

Radio waves propagating along the surface of the earth penetrate the earth to a limited extent based on their frequency, and the conductivity and dielectric constant of the earth.  For average soil and the upper frequencies of the MW broadcast band, radio waves penetrate the earth such that at a depth of ~ 30 feet, they are reduced to a value only 37% of that existing at the surface of the earth -- and less than that at greater depths.

CONCLUSION

The use of a long, buried, vertical conductor such as a deep well pipe located remotely from the base of a transmit monopole may not be as effective an r-f ground as first might be assumed. 

  *about 298 feet at 1650 kHz

TY

Rich,

Thanks for the info.

Jim

Jim Henry HBR Radio 1610, serving Honey Brook, PA. and NW Chester County.

"For average soil and the

"For average soil and the upper frequencies of the MW broadcast band, radio waves penetrate the earth such that at a depth of ~ 30 feet, they are reduced to a value only 37% of that existing at the surface of the earth -- and less than that at greater depths."

Is that saying the deeper the radials system, the less efficient??.. My understanding has been just the opposite. - (not that I would ever attempt to bury radials 30ft deep)

Rich Powers Part15, Take 2..

Depth of Buried Radials

"Is that saying the deeper the radials system, the less efficient? ... "

Yes, because skin effect forces maximum r-f earth currents to travel nearest to the surface of the earth, and reduces them at greater depths.

The critical factor here is not the amount of earth that surrounds the buried conductors, but the amount of r-f current that the earth has at the operating frequency, in the physical environment adjacent to those conductors.

 

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