Originally Posted by DEEPFRINGEGUY
A-tech was talking about the Yagi style that we're using and the site mentions that if you have a horizontal stack, like you do, that the vertical and horizontal beamwidth is more narrow than a single 91XG, for instance; in theory making them more sensitive to tilt-angle.
Back when I was designing my new rig, I went out to this site and checked my location.http://weltwireless.home.att.net/tec...alculator.html
I'm not sure if I selected the options correctly, but it came back and said that for my latitude and longitude, I should tilt downward 2 or 3 degrees for optimum signal. It seemed be able to factor in the curvature of the earth, etc. Is this all a bunch of hoowey?
I'm not sure exactly what that page is referring to. Looks like it might be wireless internet or something similar where the distances are usually short. In that situation with a high gain antenna on one end, like one of those 2.4 GHz dishes, tilting could be very important.
I tried plugging in numbers more typical for fringe area TV reception. I pretended I was out in the Sacramento Valley looking to receive Walnut Grove over flat terrain at long distances like 50 or 60 miles, using 2000' for the transmit antennas and 20-30' for the receive antenna. I get tilt angles less than 1 degree. Even two 91XGs are not that narrow. I find I need to move my antennas +/- 5 degrees to see any real change. Also I don't believe that horizontal stacking affects the vertical beamwidth. One needs to stack vertically for that.
Here's something that may be of interest, a distance to the horizon calculator:http://newton.ex.ac.uk/research/qsys...ysics/horizon/
For a TV station with an antenna at 2000', the distance to the horizon is 55 miles. If your TV antenna is at 33' (10m) your distance to the horizon is 7 miles. If you add those together, that 2000' antenna appears to be sitting on the horizon at 62 miles. You can see how important it is for fringe area reception to not have any hills in the way.
I believe the best thing you can do is to get your antenna above the local ground clutter, mostly buildings and trees, and that will maximize the signal and minimize multipath problems. Much higher than that probably won't do much good unless you get high enough to peak over some distant hill or building.
The best situation of course for fringe reception is live on top of a hill. I've often said that KSBW 8 is one of the strongest analog stations here even though it is 116 miles distant. But with their antenna at 3437' and my antenna at 2640', the summed distance to the horizon is 135 miles so they're not below the horizon here! Only any intervening low ridges would cause a problem.