[Antennas] SWR on Mobile antenna

[Chris Boone]

What kind of ground system do you have on this setup?? A tripod is NOT a
suitable ground plane for a 80/75m antenna...you need a radials.....4 60ft
long above ground will do..without the proper ground system, you have an
unbalanced antenna system, a HIGH ground loss and thus a low radiation
impedance...resulting in the 3:1 SWR....fix the ground side and your antenna
will tune better. LOW freq antennas require a ground plane or radials...and
you obviously don't have that in your current setup...the lower you go in
freq, the more critical it becomes...(this would not be a problem on say 10m
where the tripod itself would be a decent length to act as a ground plane on
10m...but on 80? You need length my man!)

Chris
WB5ITT

-----Original Message-----
From: antennas-bounces at mailman.qth.net
[mailto:antennas-bounces at mailman.qth.net] On Behalf Of Mark
Sent: Sunday, June 21, 2009 12:06 AM
To: Antenna Mailing List :>
Subject: [Antennas] SWR on Mobile antenna

Hi
     I have a mobile antenna. It is similar to a ham stick but from a
different manufacture. I am trying to adjust it for best resonance around
3.6 MHz to around 3.9 MHz. What bothers me is that the best SWR I can get is
a three to one. At the 3.9 region it is about seven to eight. I have it
mounted on a tripod for portable use. What is the best SWR I can reasonably
expect from such an arrangement?
     Thank you for your help.

God bless,
Mark