Originally Posted by Matthew Hawkins
Under ideal conditions, say you have one of those big old out door antennas like our grandparents had, and it was 30ft off the ground, what would be the maximum distance a tower could reach it with no obstructions? Talking about a full power main station like a CBS from a big city.
Probably a couple of hundred miles...you did say *ideal* conditions. I'm thinking of tropospheric propagation. Don't depend on it, though. Rare. Usually that infrequent type of propagation is more like 100 miles.
From what I understand the theoretical(?) distance is 70 miles due to the curvature of the earth (line of sight).
Lots of unknows... Age of coax cable? Length of coax cable? Preamp? Number of splitters involved? Last time antenna connections were checked for oxidation/corrosion? Is the desired station transmitting on a UHF or VHF frequency (most of the big old antennas like our grandparents used were VHF antennas). And then you get into the real technical stuff that is beyond me.
Realistically, I'd be happy with 50 miles as long as no nearby trees or buildings were between me and the transmitter. Also, look at a topo map to be sure there are no hills or mountains that could be putting you in the shadow of the signal, in other words blocking your line of sight between your antenna and the transmitter. I've got one station that is a hair over 50 miles from me that I have given up on due to a hill about halfway between me and that transmitter (20-25 miles distant). My antenna setup is far from optimal...actually it is really close to the ground. But, I can receive a mid-UHF station with my Antennas Direct DB8e consistently with it at about 40 miles. At 30' I figure it would perform much better.
But, again, I think the theoretical distance is 70 miles...or less.
I'm sure some of the antenna experts will give you some good information here, they're very knowledgeable.
Best wishes. It sounds like you've got a project!