Explain this propagation

is this something that was measured or this is a calculation? Line of sight for vhf at 1000 ft is approximately 40nm and at 1500 ft its 50nm (most pilots know these numbers). Line of sight is exactly what it says, a straight line calculation. "Radio Horizon" is how far a direct radio signal can travel across the earth and is somewhat longer than line of sight. So with 50nm being about 57 miles, that 65 mile point is perfectly reasonable.

Then there are things like tropospheric ducting where a radio wave gets "stuck" between two layers in the atmosphere and can travel hundreds or thousands of miles before it breaks out and someone can make contact. That is most common on uhf/vhf.

 

AND I said this before, RF is unpredictable and can't be always explain.

One possibility is that there is an NVIS effect going on caused by the second peak, even in mobile applications.

 

The more it bounces around the weaker it gets to..

 

As Ridgeline said it sounds a lot like NVIS propagation if you were on CB. That distance is pretty typical for that. It is not something you can rely one, as he also said RF is unpredictable.

Anyone telling you their station is 'so powerful' they can talk to anyone anywhere in the US (or elsewhere) anytime they want is full of it, especially on CB/ 10 meters. Any experienced ham can verify that.

 

Thanks for the demo, Rabbi. It's a great example of how mysterious RF can be sometimes, and that makes the hobby all-the-more interesting! The caveat for a novice is to not let the exception be the rule in regards to bragging rights. After all, this achievement was done on 4 Watts, if I correctly interpret what "barefoot" means.

 

You have to remember that Rabbi isn't using a cb radio, so the word "barefoot" is misleading.