radio fence and RF sheilding

I'm working on installing a radio fence buried-wire electronic fence for my puppy. I wish to only cover my backyard, which is quite sizeable.

The instructions proclaim the only method which will work is to double-run the wire ... so the fence wire can enter and exit the house at the same point, without crossing the door way. this is good if I were made of money and wanted to waste all that wire. Instead, I was hoping to find an alternative method.

I have some double-shielded coaxial cable (10 base-t thin net), which I tried splicing into the fence wire, where it crosses the door. This attentuates the signal, but the colar still receives it when directly over the cable.

According to the manuf. the freq is 10khz.

Is there any way I can shield the fence wire, so I don't have to make a double run of wire? The instructions proclaim that burying the wire in a metal pipe will not stop the signal and may be used where digging is likely to occur ... so this must be the same reason the shielded cable doesn't work either.

How much range does the collar have? Doorway is around 36", so guessing that to pass through, you would be within 18". Maybe the shieled cable will work if widen the opening for the doorway...

Since this is a place to build electronic gadgets... Perhaps there some circuit to disable the fence when the puppy approaches the door.

I assume it's talking about copper pipe, you could always try mild steel it might attenuate the magnetic field more effectivly.

I have some black iron water pipe, I'll give that a try ... the length of coax I tried was about 8 feet

the field strength is set to "8.5" which is just an abritrary number that works out to having the warning zone (beeping and vibrate) approx 30" from the fence and the hot zone (shock) at about 18"

i'm pretty clueless when it comes to RF ... I know a tiny bit about microwave band thanks to several large wifi projects, and that's about it.

why doesn't the braided shielding of the cable keep the signal contained, what about the faraday effect or whatever it's called?

If nothing else works, try using longer coax, as long as your house if needed.

I'm not sure how 10khz reacts with coax, especially if the coax is rated for UHF.

<I'm working on installing a radio fence
<... I wish to only cover my backyard, which is quite <sizeable.
<According to the manuf. the freq is 10khz.

< Is there any way I can shield the fence wire, so I don't <have to make a double run of wire?
< The instructions proclaim that burying the wire in a
< metal pipe will not stop the signal and may be used
< where digging is likely to occur ... so this must be the
< same reason the shielded cable doesn't work either.
...................................................................................
The wavelength of the 10 khz field is
Wavelength = v/f = 3*10^8/1*10^4 = 30,000 meter.
this means that the electric field at 10 khz practically constant over
the perimeter of a 100 meter yard.

1 or 2 meter of PERFECT shielding of the wire at the doorway
can NOT eliminate the 10 khz field produced by the rest of the unsheilded wire loop
around the yard. THe unsheilded wire easily radiates across the door too.

Threading the entire length of the 10khz fence wire thru a GROUNDED conductive pipe would vastly weaken the effects of the 10 khz electric field

In that case the wire + pipe forms a crude coaxial cable
that would have an extremely weak 10 khz electric field.
The collar would probably not operate.


hawk2eye

justDIY said:

The instructions proclaim the only method which will work is to double-run the wire ... so the fence wire can enter and exit the house at the same point, without crossing the door way.

Click to expand...

I guess I'm dense. What does this mean? Does it mean folding the wire back on itself and passing the 10kHz signal current through it? Wouldn't this create a self-canceling field? Maybe the residual field is just strong enough for the receiver to pick up at the desired short range. If this is the case, it seems to me that a complete loop around the yard would create a field that is much too strong, because there will be no cancellation.

ok, reading closer, the double loop, the wires must be spaced at least 3 ft apart, to prevent the field canclation Ron mentions

here's the website of suggested layouts:
**broken link removed**

the manuf webiste, which is down at the moment:
https://www.petsafe.com

Before you go thru all that read up on the drawbacks of those types of pet restraints. A good many pets will get daringly tough and adjust to the shock knowing it's momentary in exchange for them crossing the line to freedom. It's been done plenty.

hawk2eye said:

The wavelength of the 10 khz field is
Wavelength = v/f = 3*10^8/1*10^4 = 30,000 meter.
this means that the electric field at 10 khz practically constant over
the perimeter of a 100 meter yard.

1 or 2 meter of PERFECT shielding of the wire at the doorway
can NOT eliminate the 10 khz field produced by the rest of the unsheilded wire loop
around the yard. THe unsheilded wire easily radiates across the door too.
hawk2eye

Click to expand...

But that would mean that the dog would get shocked all over the entire yard. The range is only a couple feet or something like that.

HiTech said:

Before you go thru all that read up on the drawbacks of those types of pet restraints. A good many pets will get daringly tough and adjust to the shock knowing it's momentary in exchange for them crossing the line to freedom. It's been done plenty.

Click to expand...

i think the instanaces of failure in these systems are due to negligence on behalf of the owner. the shock is not the restraint ... pain is not the deterrent ... people that buy a system with that thinking will most likely be disappointed in its effectiveness, the animal as you point out, will quickly learn the pain is only temporary, after which, they'll freely cross the barrier.

the shock is a training tool, a physical cue to the animal it is doing something contrary to its masters instruction. dogs have very few goals, and pleasing the master is one of their highest priorities. once the animal has accepted your boundries as absolute, the collar is not even required. I have several friends who have achieved this level of success with their animals.

You know a dog can be trained without negative reinforcement, just takes a little more time and effort, but you get a better behaved animal. Mine could have escaped the backyard easy, but never even tried. Gone to bed with the front door wide open, sometimes he'd be sleeping in the carport (might have wandered, doubt it though). Use to get a lot of warnings about walking such a huge dog without a leash (no fines though). You have to spend time everyday with them. The underground fence will work fine when he's out taking a leak, but if you leave him alone for hours...

I simply make sure my dog has plenty of affectionate play and attention, both water and food in his bowls, a soft bed, some toys, and chewies..... he hasn't left the yard yet.

can a moderator please lock this thread, it stopped being useful about half way back