Point taken. 1/4 wave antennas are not truly isotropic. The vertical
seperation can be much less if gain antennas are used however, and gain
antennas give better coverage further out, which is usually a benefiet.
Wade - KR7K
----- Original Message -----
From: "Tony King - W4ZT" <[EMAIL PROTECTED]>
To: <Repeater-Builder@yahoogroups.com>
Sent: Monday, October 04, 2004 6:40 AM
Subject: Re: [Repeater-Builder] Does the R100 need duplexer if using two
anetnnas?
>
>
> >At 09:57 AM 10/2/04, Wade - KR7K wrote:
> >
> > >As long as you are using 1 antenna system for TX and another antenna
system
> > >for RX then that will work without a duplexer, if you follow a few
> > >guidelines. First, you have to use gain antennas (not 1/4 waves
verticals).
> > >Unity gain, omni-directional antennas (like 1/4 wave verticals) radiate
in
> > >all directions equally and you cannot effectively isolate one from the
> > >other.
>
> Actually, the 1/4 wave ground plane antenna doesn't radiate in all
> directions equally. Instead it has quite a hole in the pattern directly
> above the vertical radiator and they work quite when they're stacked one
> above the other, vertically, using the top antenna for receive and
mounting
> it upside down. Separation should be as much as you can stand but at least
> 30 feet. They've been used on repeaters for years. I've run several
> repeaters without a duplexer using 1/4 wave ground planes myself.
>
> 73, Tony W4ZT
>
> >Provided you have 2 antennas with some gain, I would recommend at
> > >least 9dBi, you will need enough tower or mast to vertically seperate
the
> > >antennas by 10 or 15 feet. If you are using yagi type antennas, the
same
> > >rules apply.
> > >
> > >Good luck
> > >
> > >Wade - KR7K
> > >
> > >
> > >----- Original Message -----
> > >From: "Dakota Summerhawk" <[EMAIL PROTECTED]>
> > >To: <Repeater-Builder@yahoogroups.com>
> > >Sent: Friday, October 01, 2004 5:50 PM
> > >Subject: [Repeater-Builder] Does the R100 need duplexer if using two
> > >anetnnas?
> > >
> > >
> > > >
> > > >
> > > > I have a UHF R100 and need to know if I need a duplexer if I am
going to
> > > > be using two antennas. Can someone help?
> > > > Thanks
> > > > Dakota
>
>
>
>
>
>
> 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/
