[aprssig] Scaling APRS antenna
nc8q-1 at gelm.net
Mon Sep 27 11:52:21 CDT 2004
----- Original Message -----
From: "Glenn Little WB4UIV" <glennmaillist at bellsouth.net>
To: <vk4tec at tech-software.net>; "TAPR APRS Mailing List"
<aprssig at lists.tapr.org>
Sent: Saturday, September 18, 2004 6:46 PM
Subject: RE: [aprssig] Scaling APRS antenna
> You can just change the element lengths, but, the pattern will not be as
> If you can accept the SWR, just leave it as it is since you cannot change
> the spacing of the elements and get everything at the correct spacing.
> Without changing the spacing between the elements, even if you did get the
> element length correct, you would have unexpected lobes and less gain than
IMHO, not necessarily. It might increase the gain. It might increase the
bandwidth without decreasing the gain. There was an article about a
certain commercial 11 element 2 meter antenna that worked better after
removing 3 specific elements. Typically, antennas are advertised by the
number of elements and not by boom length. It is boom length that
determines the (maximum) gain of a Yagi-Uda antenna. As long as there
are the minimum number of 'necessary' elements, there will be maximum
Does anyone remember the 2 and 20 meter Yagi-Uda antenna observations
of a Mr. Greenbaum(?) in the early 1970s?
> At 05:48 PM 09/18/04, Andrew Rich wrote:
> >Thats the thing the elements and boom are stailness steel and welded.
> >-----Original Message-----
> >From: Glenn Little WB4UIV [mailto:glennmaillist at bellsouth.net]
> >Sent: Sunday, 19 September 2004 5:17 AM
> >To: vk4tec at tech-software.net; TAPR APRS Mailing List
> >Subject: Re: [aprssig] Scaling APRS antenna
> >You will need to change the spacing as well as the element lengths.
> >This web site has some data and pointers to other web sites:
> >There is a pointer to technical info on Cushcraft antennas. Some of the
> >manuals give dimensions.
> >Hope this helps
> >At 08:36 PM 09/17/04, you wrote:
> > >Hi,
> > >
> > >I picked up a beam stainless steel 400-420 MHz
> > >
> > >How can I work out how much to cut off to bring it up to 438 MHz ?
> > >
> > >Cheers
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