Skip to main content
9 votes
Accepted

How can Ground Penetrating Radar work?

There is a special adaptation of the Friis equation, called the Radar Equation, that describes the range of a radar system. Here is a basic version that calculates the maximum range of a radar system: ...
Glenn W9IQ's user avatar
  • 18.6k
9 votes

Does geology affect radio signals?

Other Effects are there any other geological properties that can affect radio waves? Yes, there are other effects. Basically, every material affects the propagation of radio waves. Absorption That ...
Marcus Müller's user avatar
7 votes
Accepted

Not-too-distant saltwater ground

With the canal 60 feet away it's not of much help. The objective with a monopole antenna is not just to have any ground connection, but to have a low-loss ground plane under the base of the antenna. ...
Phil Frost - W8II's user avatar
6 votes

How Does the Performance of Elevated Radials Differ from That of Buried Radials?

The number of horizontal radial wires used in an elevated "counterpoise" can be far fewer than the 120 buried wires used by most AM broadcasters, and the even fewer numbers of buried wires often used ...
Richard Fry's user avatar
  • 2,922
5 votes

How thick should counterpoise wires be?

The purpose of the counterpoise is to provide an efficient means of conducting the return RF current of the antenna. In the absence of an efficient counterpoise, the current will return through the ...
Glenn W9IQ's user avatar
  • 18.6k
5 votes

Ground radials: Electrical difference between 14 gauge and 18 gauge? Lifespan difference?

Larger wire will have less resistance. However, the resistance of the radials in either case is negligible compared to the soil resistance, so I wouldn't worry about it. Longevity would be my concern....
Phil Frost - W8II's user avatar
5 votes
Accepted

How do I interpret the FCC ground conductivity map files?

Here are the fields for AM_conductivity_m3.seq_.txt and AM_conductivity_m3hw.seq_.txt files: 4001 21.5750 158.2760 21.5840 158.1900 2.00 5000.00 Fields, ...
user3486184's user avatar
  • 1,957
4 votes

Passively reducing ground loss?

It is well-established that a wire reflector --on or just above the ground-- directly under a dipole can do just that. I don't have a reference, but at a field day that I was present at years ago, a ...
Mike Waters's user avatar
  • 8,071
3 votes

Can I use electrical ground / earth as my RF ground?

"RF ground" usually means "something that is at the same potential as the soil". This is important because if you have a wire (such as your feedline, for example) which is not at ...
Phil Frost - W8II's user avatar
3 votes
Accepted

How thick should counterpoise wires be?

With only three radials, the wire you use is probably not very relevant. Although a smaller wire has a higher resistance and thus loss, with only three radials directly on the ground your losses will ...
Phil Frost - W8II's user avatar
3 votes

Does iron ore in the ground affect my signal?

Well, I operate daily from an old copper mine - where the main mineral is iron! The comment about iron oxide are not correct. In places such as here, and where the OP mentions, the ground is highly ...
John Rowlands's user avatar
2 votes

Does iron ore in the ground affect my signal?

I did find a reference in MCRP 6-22D, Marine Corp Antenna Handbook page 1-10. It talks specifically to ground wave. “At high frequencies, 3 to 30 MHz, the ground’s conductivity is extremely ...
Andrew Harman's user avatar
2 votes

Counterpoise/ground/radial options for an Inverted L

Here is another answer on this site about buried vs. elevated radials.
Richard Fry's user avatar
  • 2,922
2 votes

How thick should counterpoise wires be?

Can you elevate the radials? Two or three properly installed elevated radials can be just as effective as 120 on the ground! By properly installed, I mean that they should be roughly 10 feet high and ...
Mike Waters's user avatar
  • 8,071
2 votes

Passively reducing ground loss?

Below is the result of a NEC4.2 comparison of a 75m, center-fed dipole at 10m elevation above 15 mS/m Earth, with and without a reflector on the surface of the earth directly under it. The gain ...
Richard Fry's user avatar
  • 2,922
2 votes

Passively reducing ground loss?

Random long wires - probably will help. Especially if they're aligned with the dipole above them. Space blankets might not have a thick enough metal layer to be effective at HF, (though I know ...
tomnexus's user avatar
  • 11.4k
1 vote

How do I interpret the FCC ground conductivity map files?

The figures on that map are approximate. They represent estimated ground conductivity in millimhos per meter. And it varies with (among other things) how wet or dry the soil is. I live near a line ...
Mike Waters's user avatar
  • 8,071
1 vote

High-resolution GIS datasets of groundwave conductivity of the United States, besides the FCC?

You could get the data from e.g. the Sentinel-1 or possible the TerraSAR-X satellite missions, and look for the ground characteristics (much like for moisture estimation) that are beneficial to ground ...
Marcus Müller's user avatar
1 vote
Accepted

Counterpoise/ground/radial options for an Inverted L

Either elevated radials, or radials lying on the ground or buried just below the surface can work just fine. The difference usually comes down to what's more convenient to install. I would not ...
Phil Frost - W8II's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible