Author: Hans Hammarquist via TowerTalk <towertalk@contesting.com>
Date: Wed, 1 Jun 2016 16:45:31 -0400
It seems to me that Steve's, G3TXQ and Dan's, AC6LA diagrams coincide pretty well. You find the lowest frequency at about 1/4 wave and max frequency at about 1/2 above ground. What I don't understand
It's clearly not as simple as a "capacitance to ground" effect. The cyclic nature of the resonant frequency vs height, plus the fact that it is more pronounced over better-conducting ground, suggests
It seems to me that Steve's, G3TXQ and Dan's, AC6LA diagrams coincide pretty well. You find the lowest frequency at about 1/4 wave and max frequency at about 1/2 above ground. What I don't understand
The cyclic nature of the resonant frequency vs height, plus the fact that it is more pronounced over better-conducting ground, suggests to me that is related to the "interference" effect outlined in
You guys are way above my head :-) I had no idea the resonant freq goes up and down as the antenna travels on its way up. I thought it just went up on a steep curve till about 15 feet then gradually
It can be tough to provide a simple explanation of a complicated issue, but I tried about a week ago in this thread. :) It is FAR more than capacitance to ground, although that's a component. The com
It can be tough to provide a simple explanation of a complicated issue, but I tried about a week ago in this thread. :) It is FAR more than capacitance to ground, although that's a component. The com
Towertalk is definitely educational! I was also not aware of the way the resonant frequency changed at low heights. I still see no point in checking the SWR of an antenna near the ground. You can use
Actually, measuring SWR (or resonant frequency) might be useful close to the ground to make sure it's assembled right with the right traps, etc. The trick is you need to compare the resonant frequen
The folks from SteppIR mention just such a check in their DB18 assembly manual. It was reassuring to see it resonate somewhere on all bands before I went through the effort to get it onto the tower.
On 6/1/16 9:02 PM, Paul Braiman wrote: The folks from SteppIR mention just such a check in their DB18 assembly manual. It was reassuring to see it resonate somewhere on all bands before I went throug
Here are the resonant frequencies I measured of a 10m half-wave dipole on a telescopic push-up mast at various heights above ground in my back yard: 5ft 29.359MHz 10ft 30.499MHz 15ft 30.889MHz 20ft 3