ΑΜ radio detector

[WM6]

I will build a 500-800 mw transmitter and I would like to ask which is the most suitable antenna for the portable transmitter. 7-8 meters of wire wrapped in pvc pipe is ok?

It is best to use multiturn circular loop antenna.

Circular loop antennas can be easy angled to best wave propagation for your need.

Simplest way is to take plan for coil from BFO detector and use it as antenna (say about 20cm in diameter).

You ca use TX part circuit of adequate (to desired frequency) BFO detectors as Transmitter as well.

For local use full enough TX power.




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[taxma1981]

can the signal of the transmitter with this antenna pass to the ground 3-4 meters? And how far will it go approximately? I ask why I want to cover an area 600-800 meters distance and depth 3-4....My amplifier it is 800 mw

[Mike(Mont)]

Depends on soil type. Conductive ground is not good. Loose, dry sand not good. Saltwater very bad, graphite probably the worst. As for dry sand they recommend digging down until you get to some moisture before inserting the ground probes.

[abdou2014]

Why you need TX moving?

If you use VLF (say 33kHz alike GG AL718 ) or MW or LW,
TX should be put at fixed position and RX only is moving.
In case of MW and LW, you can use existing radio transmitter
station - no need to build your own one.

If both, TX and RX, are moving, then we talk about radar (GPR),
but radar construction ask about UHF frequencies (in MHz and
even GHz band). No such radar construction is possible in VLF,
LW or MW frequency band due to long wavelength for worthwhile
antenna construction.


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Thank you for help , my receiver receives the LW radio transmitter in all directions, how can I get a zero angle ???

[WM6]

my receiver receives the LW radio transmitter in all directions,

how can I get a zero angle ???

Depend on daytime or year season LW cam be most problematic
for radio detecting use. It can reach you from different direction.

LW can travel along Earth surface, diffract on mountains and reflect
from ionosphere. Seems your position is fired by used TX frequency
from different directions. This changes during Daytime and year season.
You need to wait for best propagation or use some SW transmitter instead LW.

Probably you can get, not total zero, but some stable minimum direction. If so,
use it. If nothing help, go for SW TX.

And don't expect 800m detecting distance, in no case, Maybe, if you divide it by 100.
3m of depth on bigger metallic deposit, this is possible and real distances are about
10m at best, if your design works as it should and in ideal conditions.




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[Jeg]

can the signal of the transmitter with this antenna pass to the ground 3-4 meters? And how far will it go approximately? I ask why I want to cover an area 600-800 meters distance and depth 3-4....My amplifier it is 800 mw

As a Transmitter you can easily use a Tesla coil grounded through a copper rod. Current oscillations move through the earth interacting with any metal in their way. Simple blocking oscillators can do the work. Look for example Kacher Brovina oscillator.

[taxma1981]

the problem is that I want to have the transmitter portable

[reza vir]

I will tell you a story from a machine that found gold in 1990.
I was told that there was a radio receiver on the ground somewhere ,another man with a small transmitter was walking opposite the receiver at a distance of 100-200 meter,
maybe there are two transmitters I'm not sure....the transmitter moves around the receiver and as the time passes it approaches the receiver,when something is found directly in the receiver and transmitter then the signal is reduced and a red light is on....in this way a box of gold was found, can a technician tell us a few words about this method?
https://ibb.co/SR5hzvh

Treasure in its surroundings
There are many different frequencies
All frequencies that are at the same angle are merged
Here we have a new frequency that hits the treasure
The output of that variable
And it can not be properly picked up with a radio receiver
You have a lot of trouble finding
With respect

[taxma1981]

effort counts, changes will be made along the way

[WM6]

List of fixed SW beacon transmitters:

http://www.dl8wx.de/BAKE_KW.htm

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[WM6]

Her you have schematic MW AM transmitter.
You can receive reflected signal by regular MW portable radio.

https://drive.google.com/file/d/12Yjb3Vw2Dr0Qa4AUOGLJELPkQlfi7KyV/view

[taxma1981]

Thanks 👍

is there a case for the transmitter and receiver to be used for cave detection?

[WM6]

Thanks ��

is there a case for the transmitter and receiver to be used for cave detection?

Signal differences in this case are to small to be useful, as well no useful reflection.

Except, if in those cave a large metallic deposit are set.

So not useful for empty caves, but with large metallic deposits in cave will go.


But you can try such SW TX RX configuration as portable two box design, this could be useful for hole detecting.
Critical is nulling (direct TX to RX signal zeroing) such two box design.




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[taxma1981]

I have started the construction of the transmitter, I finally say to make a loop antenna, I think it will be the best for my case. It should change its orientation every time I look;

[humhum]

Hi Taxma , for find Cave You can use Resonant frequency of CO2 and H with Calculator of LRLMAN .