Thanks for the plots Bob. The 2m havewave appears to do well on 70cm above 30 degrees, and fairly poor below that elevation. The 70cm 1/4 wave appears to suffer from no real nulls except at the very high elevations. It is about 5 DB down from the 2m 1/4 wave, but is also much more usable on the below 30 degree passes.
So, would a dualband that is 1/4 wave on each band cover things pretty well? It appears like it would. 73s John AA5JG On Thu, Sep 15, 2011 at 12:07 PM, Bob Bruninga <bruni...@usna.edu> wrote: > Peter, > I donno. The only 1/4 19.5" antenna I ever used I just drilled into the > roof above the dome light and installed an NMO mount and simple whip. For > conversion of an existing mount, if it is a 5/8's wave vertical (most > mobiles are) then there is a matching network in the base. > > The little tiny micro whips are ideal, but most of them now are being made > as "dual band" which then destroys their 7 dBi gain above the horizon. > > No easy answers here. > Bob > > -----Original Message----- > From: Ng, Peter [mailto:peter...@bccdc.ca] > Sent: Thursday, September 15, 2011 12:47 PM > To: 'Bob Bruninga '; AMSAT-BB > Subject: RE: [amsat-bb] Re: Good mobile antennas to use > > <snip> > But this is not what a 19.5" whip does. The 1/4 (3/4) wave 19.5" whip does > not have gain on the horizon (so it is rarely used for terrestrial mobile) > but its pattern is ideal for satellite work on high passes. It does NOT > then have a null in its pattern that causes the "crappy" contacts, and it > does have plenty of gain above about 25 degrees.... and it is a smooth > pattern.... not like the multi lobes of a standard mobile gain antenna. > </snip> > > Hi Bob, > > This is off topic and didn't want to start something on the list... :), but > can I convert my current magmount gain antenna simply by replacing the whip > or is the "gain" stuff in the magmount itself? If so, would any thin steel > rod do? I'd really like to give this a try! > > 73's Peter VE7NGP > > _______________________________________________ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
