surface wave antenna

[msucog]

i've got an oddball question: what would an antenna need to consist of to receive surface waves? and how far away could that antenna receive a signal (is there an equation that relates antenna properties, wave properties and medium properties)? also, would a vertically fixed antenna be able to receive directly from the way the antenna is pointing (so assuming long thin antenna is pointing straight up, could it receive from straight up)?

in particular, i'm curious about very low frequency (1-50Hz) surface waves travelling through the ground and being "received" by relatively long, thin (those are relative terms by the way) cylindrical concrete structures in the ground (from the ground surface doing straight down). the scenario i picture is sort of like your car antenna in the air except pointing down in to the ground. any thoughts or references would be greatly appreciated. and no, this doesn't really have to do with radio or communication but i'm certain the principles are similar. i'm using the surface waves to tell me about the medium the waves are travelling through...but in a slightly different way than is currently being used in geophysical surveys.

 

[VEBill]

There's some basic information about RF surface waves on wiki (just a starting point).

http://en.wikipedia.org/wiki/Groundwave

Given that the AM Broadcast Band at night is a classic example, you can probably answer many of your own questions about surface waves.

There are hobbiests receiving audio frequency range RF signals and detecting all sorts of interesting natural events as well as a few man-made signals.

Again, wiki is a reasonable place to start for this sort of topic.

http://en.wikipedia.org/wiki/VLF

Looks like you be looking for an old abandoned vertical mine shaft...

 

[Higgler]

Antenna's don't really exist in those frequency ranges. Look up submarine through the earth communications whereby waves in the earth's crust propagate waves. Frequencies are much higher than 50 hz though.

Antennas in the kilohertz to low megahertz are used for ground penetrating radar.

If you could be more specific on your needs, maybe you'd get a partial direction to go.

kch

 

[msucog]

thanks for the links. i will take a look. we use surface waves in geophysical surveys. in particular, using refraction microtremor (ReMi) utilizes Rayleigh waves to evaluate the soil/rock profiles. the lower the frequency geophone used, the deeper you can see. with 1Hz phones, you can see several hundred feet deep. with 14Hz phones, you can see 100-200feet pretty easily. and i'm not dealing with communication waves...i'm dealing with either source generated (sledge hammer on ground) or background noise (say from a highway thousands of feet away).

ve1bll is sort of hitting around the issue i'm looking in to but not quite. i'm trying to explain some odd (but good looking) data i've obtained on a site. what i describe in my first post is my best guess to rationalize why the data might be able to be "good". as far as all the details, i can't really elaborate about them at this time. the data shouldn't work as far as i am aware but it definitely seems to be working. while i'm trying to find where my data may be wrong, i'd also like to be able to estimate certain things just in case my data is legit. as i said before, my scenerio seems to me to be very similar to an antenna in the wind...except,upside down in the ground. so if i know about how the antenna properties and medium properties effect the reception of the waves, i might be able to explain why my model is working.

thanks for the help based on what limited information i can provide. and i'll try to provide more details once i'm able to better explain them.

 

[msucog]

i believe the vlf link may have put me on something

http://en.wikipedia.org/wiki/Extremely_low_frequency

 

[MacGyverS2000]

Did you just find Jimmy Hoffa's body? ;-)

Dan - Owner

http://www.Hi-TecDesigns.com

 

[VEBill]

Receiving ELF is going to be MUCH easier than radiating it efficiently.

And the word 'efficiently' is not being used here as in 'oh well, not that important', but as in 'my xmit antenna is melting and the system still doesn't work'.