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Mineral content in the ground varies from one place to another. I've visited places where the ground & waters were an orange-red shade from the high iron content; not good for trees either.

This post on eHam.net, seems to indicate there may be propagation issues with high iron-ore content in the soil/environs

The iron content of the under lying iron deposits were not conducive for good communications. Many dead spots. The local iron deposits are on the high ground. I experienced hf and vhf deficiencies.

The same was echoed elsewhere (pdf) about RF propagation in the Adirondack Upland, and also in the context of WWII Market Garden, and the WWII Philippines campaigns.

Anyway, say in the future I want to operate from a location where the ground is rich in iron ore.

  • Does iron ore in the ground affect my signal?
  • Assuming a fixed location, what can I do to mitigate the effect?
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    $\begingroup$ That's an interesting set of links. I suppose it's conceivable that the mineral content would cause RF damping of some sort. I can certainly understand why you might have problems with iron ore content in high ground when you're operating below it, as it could absorb or diffuse your signal rather than reflecting it as a hill ought to. I'll have to read into this some more tomorrow. $\endgroup$
    – Dan KD2EE
    Oct 30 '13 at 2:28
  • $\begingroup$ Similar to ham.stackexchange.com/questions/7711/… $\endgroup$
    – SDsolar
    Jun 6 '17 at 23:30
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    $\begingroup$ I would think that non-conductive iron ore would have a similar effect to powdered ferrite used to make choke toroids. I'm not sure, but I believe grain size and density affect frequency response and volume affects saturation levels. $\endgroup$
    – user10489
    Apr 14 '19 at 12:10
  • $\begingroup$ Please specify the types of antennas you are using. Hf what distance (ground or sky wave) and vhf with or without a ground plane. Usually the reflection is from the surface. If you have a good ground plane on a vert it’s not about the soil so much. If a long wire how are your SWR readings? $\endgroup$
    – Andrew Harman
    Dec 14 '19 at 17:16
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If anything, living in an area with high metal deposits near to the ground will improve your conditions by improving the conductivity of your ground. That said, unless it's very near to the surface and high concentration, I doubt you'd notice any difference.

Note that when we model the ground as an ideal ground plane, anything underground has no impact on the signal at all - it is shielded. Of course our real ground isn't perfect, but metal deposits can only improve that, if they have any effect at all.

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    $\begingroup$ Iron in the ground would be in the form of iron Oxide, which is an insulator. Water in the ground has the dominant effect on conductivity. $\endgroup$
    – tomnexus
    Mar 14 '15 at 13:38
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Probably not much effect from iron in the ground.

HF communications are very sensitive to the ionosphere and other natural effects. Predictions are difficult, and only give a probability, never a guarantee. Real data are thin on the ground, and you know that the plural of anecdote is not data.

HF propagation happens mostly in the air, and by reflection off the ionosphere. The ground only gets involved at the antenna, and possibly if you are using ground wave propagation. Ground wave is more an MF thing, AM radio etc, above a few MHz it is only good for a few km.

The radiation pattern and efficiency of an antenna are affected by the ground constants, and the low-angle radiation, so important for long range HF, is particularly sensitive. No matter how far the signal will travel, the only ground that counts is the patch around each antenna. The size of the patch varies, but it's generally only some wavelengths in radius. In reasonable ground, all the RF conduction happens in the first few metres, so don't worry about what is being mined far below.

The two ground parameters, conductivity and permittivity, vary widely between locations, but in general, the "richer" the soil, the "better" the ground. So fertile farmland is much better than a desert. This effect is well studied.

The richness of the ground depends on its water content, the geological type of rock etc, and the minerals. Most ground is of course silicon dioxide, sand, which is an insulator. The size of the grains, and the other minerals, are what change its performance.

Iron oxide is not conductive, so along with the SiO2, AlO2 etc, would make up the inert part of the ground. Salts and water dominate that conductive parts of the ground.

To study this further, try to investigate the effect of various minerals on the ground permittivity and conductivity. This is where the hard data lies. Stories about good and bad reception, or even careful measurements of "how good the signals are", have too many confounding factors, and are not going to lead to useful conclusions.

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    $\begingroup$ Also, the NEC2 software includes a ground modeling program where you can experiment with different values for conductivity and permittivity. Also, NEC2 (or, maybe this is NEC4) has features to model the effect of ground that has definite changes a given distance from the antenna (such as an antenna on the ground near the salt-water ocean). $\endgroup$
    – K7PEH
    Mar 14 '15 at 15:04
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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 acidic. Consequently, iron is in the FE2+ (ferric) state, not the FE3+ (ferrous/rust) state. This may or may not affect conductivity. You will have to consult a number of detailed academic papers on that, probably none of which are in the context of RF operations.

When one comes across 'red water' (pH above 4, and so iron in the precipitatable, Fe3+ state), then you know you are likely in an area with lots of different types of mineralisation. Picking out the role of each, and when geological layering and water in and through these is present, is a task that quickly leads to madness!

Are you better off with highly conductive ground under your antenna? Yes!

Parys Mountain, a Kuroko-type mineral deposit

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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 important, especially above 10 MHz where the dielectric constant or conductivity of the Earth’s surface determines how much signal absorption occurs. In general, the signal is strongest at the lower frequencies when the surface over which it travels has a high dielectric constant and conductivity.” I don’t see a case in LOS or sky wave.

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I live in the same type of area. At the bottom of a Canon and I think the iron ore is above me in the hills or I am in the middle of it, but I have terrible propagation on 11M and it even spreads out to 15M and 10M. But 11M is far the worse. At times, I can go days with nothing but static, and don't be telling me about the flip flop of the seasons. I am retired and my radio is on from 5 am to 9pm 365 days a year. I know all about the changing times. This is something else.

I think the next thing to look at is one of two things, the geomagnetic storm influence on the iron, and now I am wondering about the churning magma under the Yellowstone Super Volcano. I hear it is becoming more active and closer to the surface this year, and so is my propagation getting worse.

Just my 2 cents worth. But if you do not live in one of these areas, please stop muddying the waters with your guesses. ;)

I have since found some evidence of the Iron Ore culprit here in my little canyon. I have made a short video of what mine looks like and these rocks are laying around here on the ground anywhere there is alluvial gravel on the surface. I suspect they came out of layers above my location. Hopefully, this will add some insight to the problem, and in passing, my propagation has never gotten any better, since last posting.

https://www.youtube.com/watch?v=lge6WRF8BXM

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  • $\begingroup$ Some years ago I busted a local myth about propagation on VHF between two towns. Many were saying that there must be "some kind of ferrite" in the ground because signal in that direction was very poor... I pulled up the area in Roger's program Radio Mobile, and it turns out that there were some hills that were so gentle you really didn't see them from the road, but RM painted them red (intercepting signal) and the town behind was shadowed. $\endgroup$
    – user103218
    Dec 16 '19 at 15:08
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With respect to the issue of iron ore creating propagation problems, I have noticed the same problem where I live, which has high concentration of iron ore, for cell phone signals and sirus XM satellite reception in my car.

My theory is that, iron being a good conductor, better than air, if the ore is located between the transmitter and receiver, some portion of the signal takes the path of better conductivity, the iron ore, and less signal strength is received at the receiver.

So, assuming the validity of that hypothesis, what to do? Well, I got a signal amplifier for the house. For the car we just tolerate it.

How about driving an iron rod into the ground to pick up the diverted portion of the signal?

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    $\begingroup$ This is just not correct. Minerals in the ground don't affect cell signals. AM radio, slightly, but not as much as the water content of the ground. $\endgroup$
    – tomnexus
    Mar 14 '15 at 13:35
  • $\begingroup$ To someone who doesn't know anything about the topic, the answer sounds better than your comment- although it still is poor proof, it has a hypothesis and much more evidence. $\endgroup$
    – Skyler 440
    Mar 16 '15 at 20:22

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