• Get involved.
    We want your input!
    Apply for Membership and join the conversations about everything related to broadcasting.

    After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
    If you use a disposable or false email address, your registration will be rejected.

    After your membership is approved, please take a minute to tell us a little bit about yourself.
    https://www.radiodiscussions.com/forums/introduce-yourself.1088/

    Thanks in advance and have fun!
    RadioDiscussions Administrators

Predicting FM coverage

L

Larry the radio guy

We know that FM station signals do not stop at the horizon but actually extend maybe as much as 20% beyond. There used to be a general formula that I have long since forgotten that made an estimate of how far such signals would go. Does anyone remember it? Its seems that it started with multiplying the height of the antenna by some number and then dividing that answer by a set number or something like that. Anybody remember it? Thanks
 
Larry the radio guy said:
We know that FM station signals do not stop at the horizon but actually extend maybe as much as 20% beyond. There used to be a general formula that I have long since forgotten that made an estimate of how far such signals would go. Does anyone remember it? Its seems that it started with multiplying the height of the antenna by some number and then dividing that answer by a set number or something like that. Anybody remember it? Thanks
Click to expand...

https://www.fcc.gov/media/radio/fm-and-tv-propagation-curves
 
Works fine for me in Firefox, Safari, and Opera. It does not work in Tor Browser. Didn't investigate to see whether that's related to the Tor connection or the browser itself.
 
Yes I know about the FCC curves

Thanks for the responses so far. Yes, I know and use the FCC contour calculator but that's not what I'm seeking. I'm looking for a formula that was distributed years ago that predicted how far a useable signal would travel over the horizon. I found it to be quite reliable when driving. Thanks
 
Larry the radio guy said:
Thanks for the responses so far. Yes, I know and use the FCC contour calculator but that's not what I'm seeking. I'm looking for a formula that was distributed years ago that predicted how far a useable signal would travel over the horizon. I found it to be quite reliable when driving. Thanks
Click to expand...

I've understood the radio horizon to be about 4/3 the line of sight horizon, but then one has to factor in the effect of elevation of the transmit antenna and the elevation of the receive antenna.

This might be a start:

https://www.everythingrf.com/rf-calculators/line-of-sight-calculator

or try:

http://www.calculatoredge.com/electronics/lineofsight.htm
 
Status
This thread has been closed due to inactivity. You can create a new thread to discuss this topic.
Back
Top Bottom