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.
So even though those mountain peaks are 500 feet higher than me does this seem reasonable for my signal to travel over those Peaks? By the way this was measured after the fact. I had no idea what the terrain conditions were until after the conversation took place on the airwaves and we made a note of our physical locations. We both started out at the same location and I was stationary the entire time and we maintained contact the majority of his trip until he reached that final mile marker at which point we lost contact as he was dropping down the side of a mountain. My altitude was around 1,500 ft and there's three mountain peaks over 2000 feet that were in between me and the other Mobile station.
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.
It was barely scratching my receiver the last 45 miles. As his altitude increased, it seemed his signal got stronger.
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.
It was not done at 4 Watts. It was done without amplifiers. It was the first time in the 14 years I've lived in the area that any radio has transmitted from a distance lower than mile marker 232 to the location I was sitting.
