Thanks Kevin-you are right---my "noticed downtilt "meant to say "noticed uptilt" as the terraine inland from this site increased in HASL .
Thanks again Kevin Regards Bradley Glen --- Kevin Custer <[EMAIL PROTECTED]> wrote: > Hold on there Bradley... > > An antenna that is built for a higher frequency than > what you are > inputting will exhibit downtilt in its original > orientation. > > Kevin > > bradley glen wrote: > > Hi All > > > > I agree with Kevin and have used this in the > > commercial field where the anteena was originallt > cut > > higher than was to be used. > > > > I mounted the antenna upside-down and had good > > results-with some noticed downtilt which was good > for > > the application .On the same token keep in mind > that > > most of the efficiency of the collinear design > lies at > > the first radiating element - reduced radiation as > one > > extends to the end of the antenna. > > > > Good luck > > Regards > > Bradley glen zs5swt /zs5wt > > > > --- Chuck Kelsey <[EMAIL PROTECTED]> wrote: > > > > > >> Thanks for saving me all the typing ;-) > >> > >> Chuck > >> WB2EDV > >> > >> > >> > >> Kevin Custer wrote: > >> > >>> I think what Chuck was getting at was the > >>> > >> 'automatic' beamtilt of a > >> > >>> vertical omni collinear (usually fiberglass) > when > >>> > >> it is run outside of > >> > >>> its specified bandwidth. As a function of the > >>> > >> element length in a > >> > >>> coaxial collinear as compared to the applied > >>> > >> frequency, the vertical > >> > >>> beam pattern will change with applied frequency. > > >>> > >> If a coaxial collinear > >> > >>> is fed with a signal that is exactly on its > design > >>> > >> frequency, the > >> > >>> vertical beam pattern will be centered about the > >>> > >> antenna, and the > >> > >>> antenna will be at its highest radiating > >>> > >> efficiency. If a coaxial > >> > >>> collinear is fed with a signal that is 2% lower > >>> > >> than its design, the > >> > >>> antenna will exhibit a vertical beam downtilt of > >>> > >> approximately 3 degrees > >> > >>> and suffer approximately 10% loss in overall > gain. > >>> > >> If a signal that is > >> > >>> 2% higher than the antenna design is fed into a > >>> > >> coaxial collinear, > >> > >>> vertical beam uptilt of approximately 3 degrees > >>> > >> will occur, and again a > >> > >>> loss of overall gain. > >>> > >>> These instances are not the case with binary or > >>> > >> corporate fed dipole > >> > >>> arrays, as the phasing harness predominantly > >>> > >> controls the vertical beam > >> > >>> pattern. Beam Tilt and efficiency doesn't change > >>> > >> very much with applied > >> > >>> frequency, and is one reason that the exposed > >>> > >> dipole array is a better > >> > >>> choice where wide band operation is required. > >>> > >>> Kevin Custer > >>> > >>> skipp025 wrote: > >>> > >>>> Kind of loaded question/statement/answer > really. > >>>> > >> All > >> > >>>> antennas have both horizontal and vertical > >>>> > >> beamwidth. > >> > >>>> Depending on what you think is beam-tilt... one > >>>> > >> could > >> > >>>> and some do say all antennas have a beam tilt > and > >>>> > >> or > >> > >>>> a beam width. Others combine the description... > > >>>> > >>>> In the more commercial world of antennas, we > now > >>>> > >> see > >> > >>>> vertical omni repeater site antennas with > >>>> > >> adjustable > >> > >>>> beam tilt. > >>>> > >>>> But I'm not sure if I'd say they have to be > made > >>>> > >> with > >> > >>>> fiberglass radomes (covers). There's more than > >>>> > >> one method > >> > >>>> used by the various mfgrs to adjust the beam > tilt > >>>> > >> - beam > >> > >>>> width. For the most part we only see some > models > >>>> > >> with > >> > >>>> adjustable setting in some vertical omni models > >>>> > >> with > >> > >>>> composite radomes. > >>>> > >>>> ... and you pay serious money for the > adjustable > >>>> > >> beam > >> > >>>> tilt models. If you pay attention to the > specs, > >>>> > >> you'll > >> > >>>> see values for the horizontal, vertitcal beam > >>>> > >> width and > >> > >>>> where needed, the/any adjustable beam tilt > >>>> > >> values. > >> > >>>> Your results will probably vary... > >>>> > === message truncated === __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
