VLF transmitter & antenna

[Roger Sterling]

Hi folks,

To say that I am a neophyte would be an understatement, so any advice would be appreciated. I am wanting to know if it would be even possible to build a VLF transmitter and antenna to broadcast just a simple pulse to a receiver about 100-150ft away or are these things available for purchase somewhere. I am willing to spend a couple hundred bucks.

Cheers!

 

[davenn]

welcome Roger

yes it is, what freq did you have in mind ? what are the local laws in your country concerning the use of transmitters?

cheers
Dave

 

[Roger Sterling]

Dave:

I am located in the U.S. and my understanding is that at the VLF frequency and the short range I have in mind that it is legal. The application is an already existing underground electronic perimeter fence that my father has installed to contain his very small dog. The collar the dog wears sprays a burst of citronella when he gets to close to the buried VLF wire antenna when attempting to escape from the yard.

The issue is that he also is also doing a lot of barking to which the neighbors are none too happy and that multiple professionals have not been able to correct. The dog is a toy terrier who only weighs a few pounds and rather than have him wear two collars my thought would be that we could utilize the citronella collar he already wears to remotely give him a a correction to help bark train him. Ideally it would be something that my dad could just press a button to send the signal to the receiver collar when he hears the dog barking. So to answer your question, I believe the VLF transmitter is sending a 7Khz or 10Khz frequency through the underground copper wire antenna. This VLF radio signal activates the receiver on the dog collar which sprays the citronella when the dog gets to within 5 feet of the underground line. I will try to find out for sure but any preliminary advice would be appreciated. Thanks!

 

[davenn]

ok,
damn, thats low, never done any transmitting that low, only receiving of atmospherics. most of my RF work is at the other end of the spectrum in the microwave bands

Dave

 

[Roger Sterling]

Does that mean I am probably out of luck?

 

[davenn]

it may be worth talking to the company that supplies the existing system and see if there was a way to modify / add another transmitter that you could use for your purpose

its worth a try

Dave

 

[MattyMatt]

I would honestly agree with Dave on this one...

There may also be a way to "piggy back" using a different frequency, like put a receiver on to the existing transmitter.... sorry if that doesn't make a lot of sense. What I envision, is basically attaching a higher frequency reciever to the current box that transmits on VLF, you can probably get away with a few different frequencies, and maybe improved range.

... sorry, its getting late for me.