Ham Radio Forum

I am trying to help stop rhino poaching and am trying to get this idea into operation:
A metal detector is placed on or in the rhino horn that has a transmitter attached so that when a metal saw is close to the horn a message is sent electronically to game rangers. The horn has another transmitter that keeps transmitting whilst the horn is being taken away in a poacher helicopter.
NOW here is the problem: The poachers could put a Faraday Cage around the horn when they have it in the aircraft. Is there any way to make a Faraday Cage transmit the signal from the transmitting device in the horn (or perhaps the aircraft could act as a transmitting antenna)?
Thanks

That is an interesting problem and creative potential solution. However, some questions immediately come to mind (not stated here in any particular relational order):

1) Couldn't a single transmitter serve both to alert game rangers about the proximity of a metal saw-blade and to provide a tracking signal during transit?

2) If poachers knew in advance that such an anti-poaching method was being employed, couldn't they cut rhino horns using a non-metallic saw of some type that wouldn't trigger the alarm?

3) If they didn't know, isn't it unlikely that they would have the technical knowledge to employ a Faraday Cage or be equipped to use one?

4) Wouldn't it be difficult to hide a tracking transmitter sufficiently well that poachers wouldn't see it and simply destroy or otherwise disable it?

As to your question about making a Faraday Cage transmit a tracking signal, that wouldn't be practical. A very small amount of RF energy leaks from any Faraday Cage, even a cage with no openings made from solid silver or some other good conductor. The percentage of energy that leaks depends on the conductivity of the cage wall material, its thickness, the cage dimensions, the sizes of any openings, their positions relative to the internal transmitting antenna, the frequency of the RF energy, and other factors. However, if poachers simply put horns into most any closed metal box the amount of energy that would leak from a small battery-powered transmitter inside would be far to small to be useful for position tracking.

The body of a helicopter could serve as a transmitting antenna if RF energy of an appropriate frequency was properly coupled into it. However,

1) Helicopters are physically too large and wrongly-shaped to function as efficient transmitting antennas at the frequencies commonly employed for wildlife location-tracking by means of small transmitters.

2) The energy that would escape a metal box serving as a Faraday Cage would be far too weak to provide a useful tracking signal even if it was efficiently coupled to the body of a helicopter.

Thanks for the info. What about generating a magnetic field from inside a Faraday cage? Detection of magnetic fields is used in geophysics. Could one generate a pulse magnetic field from inside a Faraday cage that could be used for tracking?

There is no way to produce a magnetic field inside a rhino horn that would be strong enough to allow position tracking over the required distances. Furthermore, even if that could be done the magnetic field would interfere with helicopter navigation equipment.