Guy Olinger K2AV wrote: > Counting FCP segments 1 through 5. 33 feet per segment. Directions > used are for illustration only. > > 1: center to 33 feet east > 2: 33 feet east back to center > 3: center to 33 feet west > 4: 33 feet west back to center > 5: center to 33 feet east and end insulator.
Your analysis IMHO doesn't take into account coupling between the two conductors in the open wire line. I would characterize the above as a 33 foot radial in series with two 33 foot shorted stubs. A 33 foot shorted stub made of 600 ohm line is equivalent to about 20 microhenries of inductance. Two of those add up to 40 microhenries. This is close to the 55 microhenry loading coil you mentioned. Using a shorted stub of OWL to implement an inductor is an implementation decision. It seems less lossy because it doesn't get hot; the heat is spread out over a large area. But you still have the copper losses of a considerable length of wire which add up to a similar amount of loss that a big coil would have. You're probably right that it's cheaper than a coil, at least if you buy it new. Again, nothing wrong with doing this; I'm sure it works, but there is nothing magic going on here. It sounds like a nice ham-proof implementation of short elevated radials, which can be tricky to install the usual way. I don't see how any of this improves bandwidth except to the extent it adds loss to the system. There is a known relationship between antenna size, bandwidth and efficiency. Networks on the ground don't fundamentally affect this. Replacing an inductor with a shorted stub is always detrimental to bandwidth because the inductance of the shorted stub is proportional to frequency, instead of constant like the inductor. Rick N6RK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
