New detecting method?

[WM6]

Chris, this is done 50 years ago for prospecting. For induction balance and to suppress GND signal from soil surface, ferrite rods are not exactly perpendicular.

Hi mikebg, those are aldest model, newest are some different:

"Transmitter and receiver dipole orientations of the EM38-DD and DUALEM-1S (instruments are oriented parallel to the surface). The loops of wire form a solenoid and a dipole is created when current passes through the wire. The EM38-DD (top) has its transmitter and receiver dipoles oriented in horizontal–horizontal (H–H) and vertical–vertical (V–V) modes. The DUALEM-1S (bottom) also uses a V–V and a vertical–horizontal (V–H) mode for the dipoles in its transmitter and receiver."

The 4 most common types of EMI instruments, are the EM38, EM31, EM34 and EM39. Although they all operate the same, they vary in the depth to which they read within the soil profile. All operate in both the vertical and horizontal mode (this determines the depth to which they read). A summary of this is given below:

EM38 - vertical mode (1.5m) horizontal mode (0.7m)
EM31 - vertical mode (6.0m) horizontal mode (3.0m)
EM34 - 6.0m to 60.0m
EM39 - used for logging down boreholes.

These depths are only indicative, as the depth of penetration of the electrical signal will be determined by the uniformity, or non-uniformity, of the soil. If the soil is very conductive near the surface then the signal will be dissipated and will not read to a greater depth.

[Geo]

Hi Geo.
Forgive my English, I have different translators, none technical.
To new idea the best magnetic aerial is needed to Tx, for good irradiating the area. Best if only the entire energy went to one's grave as the magnetic component, Tx Energy radiated by the area is completely unnecessary and harmful.
I am looking for something better than the ferrite vertical antenna in my memory and good books. I want energy fields 10 - 100 miliwat of the radiation. And ferrite will already be then too weak.
He is staying to bury to the earth frame antenna. Other idea of the antenna, can stick 2 probes to the earth, and made Tx in the B class push-pull. GND connect with 3rd probe.
A few attempts I will make in spring.
Best regards Chris.

Hi Chris.
The idea of the probes to the ground is not good if you want to use the detector as mobile detector and not as "constant".
For vertical antenna a simple spiral antenna is a good solution. I worked with a similar one

Regards

[mikebg]

Hi Geo.
It looks like a mini two-box.
And I think the 2 antennas with a vertical magnetic polarity, the land
component preferably disperses component magnetic field the electromagnetic field.
Maybe someone is thinking of something better than the ferites
antenna.
Vy 73 Chris

Chris, this is done 50 years ago for prospecting. For induction balance and to suppress GND signal from soil surface, ferrite rods are not exactly perpendicular.

[Seden]

Ground Antenna

WM6,

You may be right as so far I have never made one, just read about the Amatuer's experiences.

Well then it's top loaded vertical with MANY ground radials and a large capacity hat. Yeah it can be done in the field with some guy wires,maybe buy the portible antenna setup the military uses that are sold to Amatuer Ops for field day operation.

Randy-WD6ELU

[WM6]

seems to work out well and you can resonate and impedance match a ground antenna by the way.

Randy, those "impedance match" work with resistive component of soil. Nothing to do with resonance of antenna (Q are practically nonexistent). This is only additional antenna load that maybe help to not burn TX output transistor.

[Seden]

Ground probes = more effective

JP,

In the reports I've read from the Amatuer Op's in Europe operating at 73K.C.'s, a ground rod as short as 18" seems to work out well and you can resonate and impedance match a ground antenna by the way. A Google search using 73khz amatuer band will get you lot's of hits.

For a permanent home setup I much prefer the 8' copper rods used for grounding home electrical systems to give me more cross sectional area which decreases the resistance obviously and less susceptible to variations in soil conductivity via drying out in the summer heat.

Works for me.

Randy

[WM6]

When it comes to the gold gun sold whith a transmiter the electronics designer prefered sending the signal direct into the earth using probes.

g-sani, antenna have to be in resonance to be effective. By such design with two to TX wired probe, you never reach resonance and antenna efficiency is very very low (except in way to burn transmitter).

Properly grounded and resonate tunned antenna on ULF/VLF band is at the same time ground and air antenna and with way better propagation, because we are speaking here about wave reflection and not about eddy current induction.

[J_Player]

... the ground antenna is the best of all. This is something I will be working with as well. In my books on VLF, a top loaded vertical with a big capacity hat would be 2nd best but you still have to supply lots of ground radials for it to be efficient. I have been talking to another Amatuer Radio Operator on 1853.5 KC for 25 years using Single Sideband so I know from first hand experience what makes a good LF antenna.

The ground antenna does not work as good at the upper end where I work(L.F.). Ground Antennas work good below 50KC. Make sure you space your ground rods as far from pole to pole as you plan to walk around.

Randy

Hi Randy,
If a person wanted to build a ground antenna to operate at 30 KHz, what actual hardware materials and sizes do you recommend he should he use for this antenna?

Would the apparatus for a treasure hunter's portable field antenna be significantly different than what you would recommend for a permanent installation used in communications?

Best wishes,
J_P

[g-sani]

..Other idea of the antenna, can stick 2 probes to the earth, and made Tx in the B class push-pull. GND connect with 3rd probe.
A few attempts I will make in spring.
Best regards Chris.

I believe thats more comfortable for the treasure hunter.
And from one point of view is more practical even for the electronics engineer while having a major problem solved.
When it comes to the gold gun sold whith a transmiter the electronics designer prefered sending the signal direct into the earth using probes.

[Seden]

Ground Antenna

Chris,

You are correct, the ground antenna is the best of all. This is something I will be working with as well. In my books on VLF, a top loaded vertical with a big capacity hat would be 2nd best but you still have to supply lots of ground radials for it to be efficient. I have been talking to another Amatuer Radio Operator on 1853.5 KC for 25 years using Single Sideband so I know from first hand experience what makes a good LF antenna.

The ground antenna does not work as good at the upper end where I work(L.F.). Ground Antennas work good below 50KC. Make sure you space your ground rods as far from pole to pole as you plan to walk around.

Randy

[Krzysztof]

Hi Geo.
Forgive my English, I have different translators, none technical.
To new idea the best magnetic aerial is needed to Tx, for good irradiating the area. Best if only the entire energy went to one's grave as the magnetic component, Tx Energy radiated by the area is completely unnecessary and harmful.
I am looking for something better than the ferrite vertical antenna in my memory and good books. I want energy fields 10 - 100 miliwat of the radiation. And ferrite will already be then too weak.
He is staying to bury to the earth frame antenna. Other idea of the antenna, can stick 2 probes to the earth, and made Tx in the B class push-pull. GND connect with 3rd probe.
A few attempts I will make in spring.
Best regards Chris.

[g-sani]

You do not know this old rocker? Probably you are too young.

Yes I think it was a biggest dowser ever, look at the penultimate verse.

Yes,I think he must have been lucky at least once discovering treasure so he knows how sweet it is.

[Geo]

Geo, are you tried to put your ferrite antenna in RFI protective housing made from can of beer (one side open) and connected to ground of oscillator?

Hi WM6,
No... i did not tried to make anything with ferrite. The only that i did was a replacing of ferrite with a simple bigger coil, with the same problems....

Regards

[Geo]

Hi Geo.
It issues me, that secret sticks (lie) in (to) in antenna with vertical magnetic polarization.
So as vertical feryt, we search something better.
And f max< 32kHz.
Vy73 Chris.

I don't understand what you are saying about!!!

[WM6]

Nice poetry WM6 but I never herad of Willy Shake.
Was it a treasure hunter as well?
Not a dowser anyway!

You do not know this old rocker? Probably you are too young.

Yes I think it was a biggest dowser ever, look at the penultimate verse.