Thanks Roger Looking at the suggestions it seems to me that if you do the calculations the antennas could be designed at 100 OHM feed impedance.
Taking into account that you use 75 throughout the harness-antennas =100 Ohm Z . If anyone can comment further on the harness as I am going on assumed givens as I do not have one to confirm this. Regards Brad ZS5WT --- "Rogers, Ron" <[EMAIL PROTECTED]> wrote: > Yep folks, these are commonly referred to as > "Phasing Harnesses" just like > we use in the contest circles to stack multiple > antennas and phase them so > the feed point impedance still "sees" 50 ohms at > the design frequency. > > Ron Rogers > -WB8ERB- > > -----Original Message----- > From: Steve Grantham [mailto:[EMAIL PROTECTED] > Sent: Thursday, April 15, 2004 3:14 PM > To: [email protected] > Subject: Re: [Repeater-Builder] Decibel repeater > antenna question-unbalanced > radiating loops > > > I think you will find that the feed point is 50-Ohms > when feeding one of > these single unbalanced dipole elements. The > harness is for making the > multiple elements on the array look like one element > to the transmission > line. Look at their (DB's) folded unipole antenna > for low band. It's a > ground-plane antenna with a similar radiating > element that's fed with 50-Ohm > line. The difference is that it's got radials on it > instead of a mirrored > counterpoise. There may be other subtle > differences, but... > > Steve, aa5sg > > ----- Original Message ----- > From: Paul Guello <mailto:[EMAIL PROTECTED]> > To: [email protected] > <mailto:[email protected]> > Sent: Thursday, April 15, 2004 1:19 PM > Subject: Re: [Repeater-Builder] Decibel repeater > antenna question-unbalanced > radiating loops > > There are not any baluns on these antennas. If I > remember right, they use > 75 ohm coax on each bay (odd multiples of quarter > wave length) and 35 ohm > coax on the feed (again odd multiples) to match the > impedance to 50 ohms. > This info was on the group a while back, somebody > must still have it. > > Paul, kb9wlc > > > > Mathew Quaife < [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> > wrote: > > Would a close up pic of a DB304 work for your needs, > or I have the DB420 > there as well. > > Mathew > > > bradley glen <[EMAIL PROTECTED]> wrote: > > Hi > > I have been studying the db stacked array and the > bayed array seems to use unbalanced dipoles as the > radiators .I have tried to find a close up view of a > single dipole so I can confirm my ideas. > > If anyone has some good tech info on these antennas > I > would appreciate the info. > > It would make sense to " by-pass " the need of > baluns > for each dipole -cost and balun loss????? > > Regards > > Brad > ZS5WT Repeater Owner > [EMAIL PROTECTED] > > > > > > > __________________________________ > Do you Yahoo!? > Yahoo! Tax Center - File online by April 15th > http://taxes.yahoo.com/filing.html > > > > > > Yahoo! Groups Links > > > > > > > > > _____ > > Do you Yahoo!? > Yahoo! Tax Center - File online by April 15th > <http://taxes.yahoo.com/filing.html> > > > > > > > > > > _____ > > Do you Yahoo!? > Yahoo! Tax Center - File online by April 15th > <http://taxes.yahoo.com/filing.html> > > > > > > > > > > > > > > _____ > > Yahoo! Groups Links > > > * To visit your group on the web, go to: > http://groups.yahoo.com/group/Repeater-Builder/ > <http://groups.yahoo.com/group/Repeater-Builder/> > > > * To unsubscribe from this group, send an email to: > [EMAIL PROTECTED] > <mailto:[EMAIL PROTECTED]> > > > > * Your use of Yahoo! Groups is subject to the Yahoo! > Terms of Service > <http://docs.yahoo.com/info/terms/> . > > > __________________________________ Do you Yahoo!? Yahoo! Tax Center - File online by April 15th http://taxes.yahoo.com/filing.html 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/
