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# Frequency Bands and distance

## Frequency Bands and distance

(OP)
I am trying to figure out/locate the distances that the bands S, C,X,Ku, etc... can operate using LOS. I also need what frequencies S,C,X,Ku etc... correspond too.
Thanks...Tom

### RE: Frequency Bands and distance

There is no hard distance limit on any particular band.

One rule-of-thumb formula for pathloss is:
Pathloss(dB)= 32.45 + 20*log(MHz) + 20*log(km)

This assumes simple 'free space' propagation and ignores the atmospheric effects.  It can be seen that pathloss goes up with frequency, but so does practical antenna gain.

Consideration of maximum distance needs to include a complete end-to-end analysis including antennas, power, atmospheric losses (eg. water), coding gain, bandwidth, receiver, etc.

Obviously, once you hit an obstacle (like the horizon), then you're no longer LOS.

In answer to your other question about the alphabet soup of bands, here is just one chart:
http://www.geo-orbit.org/sizepgs/spectrumchartp.html

### RE: Frequency Bands and distance

To add to what VE1BLL stated here are some links for  atomspheric attenuation effects, which can alter the free space attenuation.  Also rain can effect some frequecies
Checkout:
http://www.rfcafe.com/references/electrical/atm_absorption.htm
http://web.haystack.mit.edu/haystack/files/AtmAtt.pdf
http://sina.sharif.ac.ir/~barkeshli/antennas/review/9510_031.htm
http://satjournal.tcom.ohiou.edu/issue02/pdf/paper_asoka1.pdf

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