Hi Guys and Girls. Is there a location where I can get more info on the theory of collinear antenna's. They are used allot here in OZ at least over the past 30+ years that I have been in the game. I have read info on phasing multiple dipoles. TIA Brett
----- Original Message ----- From: "bradley glen" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com> Sent: Sunday, April 09, 2006 6:37 PM Subject: Re: [Repeater-Builder] down tilt > 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... >> >> >> >> cheers, >> >> skipp >> >> >> >> >> >> >> >> >> >> >> Yahoo! Groups Links >> >> >> [EMAIL PROTECTED] >> >> >> >> >> >> > > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > > > > > > Yahoo! Groups Links > > > > > > > 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/
