Home |
Search |
Today's Posts |
#1
|
|||
|
|||
metal dector for barbed wire fences
rec.radio.amateur.antenna
metal dector for barbed wire fences Anybody here have any suggestions for possible ways to detect fence wire, mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix? Typical mounting would be on a tractor or trailer, so the detector would need a sense of direction, ie looking outward not inward. Minimum range would be around one foot with 4 feet probably optimum. Typical retail metal detectors have a short range and need a metal free environment, leaving the methods they use somewhat doubtful. Evidently, there are detectors with seperate heads/coils and 1-5 foot ranges but, once again, require a metal free environment. One possible area would utilize rf antenna's, one transmiting and the other recieving a reflection from the wire(s). A parabolic or corner reflector type antenna maybe if not for the high frequency - two 12 inch antenna's would be about max size and that's in the gigaherts range, which might be a problem. Any suggestions along this line will be appreciated. Hul |
#2
|
|||
|
|||
metal dector for barbed wire fences
If there is a free end accessible you might try feeding some rf into it
and then following along with a receiver to detect the underground portions. This may or may not require strong attentuation at the receiver antenna -- using a short loop or something across the input. If there is one level. chances are you may find others underneath with a little digging unless there are accessible ends to them whereas tracking the RF would work just as well. Just a wild and maybe not so crazy idea of how I'd try for a quick cheap fix. Irv VE6BP "Hul Tytus" wrote in message ... rec.radio.amateur.antenna metal dector for barbed wire fences Anybody here have any suggestions for possible ways to detect fence wire, mostly 1, 2 or 3 levels of barbed wire but also some 8 inch square matrix? Typical mounting would be on a tractor or trailer, so the detector would need a sense of direction, ie looking outward not inward. Minimum range would be around one foot with 4 feet probably optimum. Typical retail metal detectors have a short range and need a metal free environment, leaving the methods they use somewhat doubtful. Evidently, there are detectors with seperate heads/coils and 1-5 foot ranges but, once again, require a metal free environment. One possible area would utilize rf antenna's, one transmiting and the other recieving a reflection from the wire(s). A parabolic or corner reflector type antenna maybe if not for the high frequency - two 12 inch antenna's would be about max size and that's in the gigaherts range, which might be a problem. Any suggestions along this line will be appreciated. Hul |
#3
|
|||
|
|||
metal dector for barbed wire fences
"Irv Finkleman" wrote in message ... If there is a free end accessible you might try feeding some rf into it and then following along with a receiver to detect the underground portions. This may or may not require strong attentuation at the receiver antenna -- using a short loop or something across the input. If there is one level. chances are you may find others underneath with a little digging unless there are accessible ends to them whereas tracking the RF would work just as well. Just a wild and maybe not so crazy idea of how I'd try for a quick cheap fix. Irv VE6BP Good idea. RF tracking works very well for buried cables and should work for fence wire. I used it some years ago when we were adding antennas to an existing field and needed to know exactly where to dig only by hand. The device is in two pieces, one of which couples RF onto a cable by induction (from up to several feet away); the other piece is a receiver which detects the re-radiation from the cable up to several feet away. The transmit unit and the receive unit need to be separated about fifty feet apart or more for this to work. Otherwise, you will get direct coupling through the air and not via the conductor you're tracking. The receiver sensitivity was adjustable on the one I used. I rented our unit from a surveyors' supply house. Rent, try, buy. good luck. "Sal" |
#4
|
|||
|
|||
metal dector for barbed wire fences
Might be worth trying a standard electric fence generator. These put in a
pulse of a few 10,s of kv( as far as I know) Probably pick it up as a 'click" on a standard AM/FM reciever. These blokes could maybe suggest a better antenna. Just make sure you if you need a leak you dont use the fence post!!!!!. "Sal M. O'Nella" wrote in message ... "Irv Finkleman" wrote in message ... If there is a free end accessible you might try feeding some rf into it and then following along with a receiver to detect the underground portions. This may or may not require strong attentuation at the receiver antenna -- using a short loop or something across the input. If there is one level. chances are you may find others underneath with a little digging unless there are accessible ends to them whereas tracking the RF would work just as well. Just a wild and maybe not so crazy idea of how I'd try for a quick cheap fix. Irv VE6BP Good idea. RF tracking works very well for buried cables and should work for fence wire. I used it some years ago when we were adding antennas to an existing field and needed to know exactly where to dig only by hand. The device is in two pieces, one of which couples RF onto a cable by induction (from up to several feet away); the other piece is a receiver which detects the re-radiation from the cable up to several feet away. The transmit unit and the receive unit need to be separated about fifty feet apart or more for this to work. Otherwise, you will get direct coupling through the air and not via the conductor you're tracking. The receiver sensitivity was adjustable on the one I used. I rented our unit from a surveyors' supply house. Rent, try, buy. good luck. "Sal" |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|