Radio wave propagation question

[Citizen]

Regarding radio wave propagation, I know LOS is most important, and to get true LOS, antenna height is king.  Power output is secondary but still is important.  That said, something unusual happened a few years back that I have not been able to explain, and which challenges the above dogma.

 

My wife and I spent a few days at Petit Jean Mountain in Arkansas.  We stayed in a cabin at the State Park.  On one afternoon, I wanted to go hiking, but my wife wanted to stay back in the cabin and make a few calls to relatives.  So I took a FRS/GMRS HT with me, and left one with her in the cabin, which was on top of a bluff area.  I proceeded on a trail into a deep forested canyon and down to a river to view a waterfall.

 

The strange thing is, and is the bases of my question, is that I was able to talk to her via the HT radios the entire time I was gone.  It was basically crystal clear communications.  But in no way on earth (literally) was it LOS.  LOS would have had to go through solid rock and then a very thick forest. 

 

So the question is; how were the radio waves able to get through all that blockage?  I don’t think reflection could have propagated so far down a canyon as to get to the bottom (probably a few hundred of feet, not so much, but you can see in the picture how much rock the signal would have to get through, and then I was under a forest canopy).

 

What do you think?

 

...

[kidphc]

That is the thing with propagation studies. You can get reflections, knife edge propagation, localized ducting. Any number of things could have occurred. Which make it better or worse.

 

Funny enough even the type of foliage can aid or hinder propagation.

 

Have you headed back up there since? Was the weather different?

 

 

 

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[berkinet]

Also, Fresnel zone effect: http://radiomobile.pe1mew.nl/?Calculations:Propagation_calculation:Fresnel_zones

 

BTW, At UHF frequencies, once you have LOS, power makes little additional difference.  The higher you go in frequency, the more true that becomes.

[kidphc]

Also, Fresnel zone effect: http://radiomobile.pe1mew.nl/?Calculations:Propagation_calculation:Fresnel_zones

 

BTW, At UHF frequencies, once you have LOS, power makes little additional difference. The higher you go in frequency, the more true that becomes.

Intesting read... would of thought there would have been more picket fencing from multi pathing. But it seams you basically are going to get crystal clear or nada due to phasing.

 

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[JLeikhim]

You might want to use some of the features in Google Earth to draw the paths using the line feature and then viewing the elevations.

[gman1971]

This site will create a radio coverage map for any location, of your choosing. No guesswork.

 

Radio Mobile online.

 

G.