[TowerTalk] Expected VSWR of antenna near the ground

[john at kk9a.com]

I usually pull my antennas straight up the tower.   It is easy for me climb
up with a MFJ analyzer and make an accurate assessment before bolting the
antenna in place.  If I wish to make an adjustment it is easy to drop it
down adjust it and try it again. 

 

John KK9A

 

From: K7LXC at aol.com [mailto:K7LXC at aol.com] 
Sent: Monday, September 28, 2015 4:15 PM
To: towertalk at contesting.com; john at kk9a.com
Subject: Re: [TowerTalk] Expected VSWR of antenna near the ground

 

>  It is a waste of time checking an antenna near the ground. About the only
thing you can determine is if the coax is connected. You need to pull it
up at least 30' high.

 

    Yes, 30' high is a truer picture of the antenna resonance (which is
probably the number of greatest interest) but I ALWAYS put an antenna
analyzer on an antenna on the ground. What I'm looking for is that it looks
like an antenna; that is, it has a dip somewhere. No dip? Something's wrong.


 

    A dip shows that it acts like an antenna. Where is resonates is
typically below the band due to added ground capacity but that's what you'd
expect. So if it resonates below the band, it looks like an antenna and
resonates around where it should. 

 

    Actual resonance is shown when it's up in the air but it's never an
empty test to do it when it's on the ground. 

 

Cheers,

Steve    K7LXC

TOWER TECH