Bob, this is a business proposal Joel is doing, not a Sunday experiment. With no estimate of performance there is no case, and I think the basic info looks bad for your suggestion of just bouncing off the tower. We haven't gotten anywhere close to an analysis of Joel's model yet because these numbers (mine anyway) are just rough-order-of-magnitude estimates. The water tower (assuming it's a cylinder - worse if a sphere) is dispersive, so that "reflector" would look kinda like extending the path by about 10-15 miles. However, there would be SOME signal in the right direction where there is none (ie, blockage) in the direct line of sight. Hams usually can just use more power and swamp out loss with a 100 or more watt transmitter and not be too worried about some holes in the coverage pattern or fades on a bad day. > -----Original Message----- > From: tcwug-list-admin at tcwug.org [mailto:tcwug-list-admin at tcwug.org]On > Behalf Of Bob Gilbertson > > > Well, my point wasn't to do an exhaustive engineering analysis, just > point out what may be an overlooked solution. > Putting stuff on the tower may be difficult with permits, > permission, rent > and liability if something flies off in a wind. > Securing permits to erect a 200' tower may be interesting > also, which was > another option he mentioned. > > Given the distance involved and the antenna gain stated it > seems possible. > Kinda depends on what kind of link reliability they require too. > > Just suggesting to try the easy stuff first. > > Bob > > Chuck Cole wrote: > > > >>-----Original Message----- > >>From: tcwug-list-admin at tcwug.org > [mailto:tcwug-list-admin at tcwug.org]On > >>Behalf Of Bob Gilbertson > >> > >>Depending on the angles involved to the tower, and the tower > >>shape you may > >>be able to just bounce the signal off the tower itself. > >>Wouldn't take much > >>to try it. 21 dB over isotropic is aiming quite a bit of > >>signal in the > >>desired direction. Same concentrating effect is seen on the > >>receive side. > >>If you're driving, say, 100mW into the antenna this would > >>give about 10 Watts > >>ERP, which is a robust signal at 2.4 Ghz. > > > > > > > > Those numbers don't go together to make a path estimate. > ERP doesn't affect > > actual watts per square meter field strength at the tower: > it's only saying > > that a bigger transmitter on a dipole would do the same as > the 100mW on a > > parabolic. The tower is probably cylindrical which is > dispersive and thus a > > lossy reflector at best, and its vertical angle isn't good > for a bounce > > either. The receiving antenna's area is the only > concentrating effect > > there: square meters for an incoming wavefront of some > watts per square > > meter power density, so the result is some microwatts down > the coax pipe. > > > > > > Might work, but looks feeble. > > > > > > Chuck >