Author: Tony Reynolds" <kb8jvh@reydata.com (Tony Reynolds)
Date: Sun, 10 Feb 2002 12:29:41 -0500
Hi, and thanks for reading. I'm working on modeling a shortend vertical for 160 I want to build. The model can be downloaded from: http://www.reydata.com/160kb8jvh.ez if you wish to take a look. I'm
You ALWAYS want to use some sort of "hat" at the top of a vertical. If you make the capacitance of the hat large compared to the distributed capacitance in the vertical, the current will be uniform
Tony Tom W8JI's comments are good, and my 2 cents is that your modeling is "in the ballpark" concerning bandwidth, feedpoint Z and increased loading inductance as it is placed higher on the structure
Tony I'll coat-tail on Tom's comments. I've gone through somewhat the same exercise you are. I now use a vertical 40 ft tall with a cage structure. That is, the vertical section is three #17 wires in
Author: Tony Reynolds" <kb8jvh@reydata.com (Tony Reynolds)
Date: Mon, 11 Feb 2002 18:11:31 -0500
Wow!!!! What a group of knowledgeable folks. I thank each and everyone of you for your input. I certainly have learned alot about verticals. It's back to the keyboard for more design work. I've got 6
Hi Tony, Most of the bandwidth in a loaded system (like a short vertical) comes from keeping reactance low, so system Q is low. Remember in a series resonant circuit, less reactance means lower Q. (
Hi Tom, Very good info! I had already modeled a thicker vertical element and was surprised at how little difference it made. The series resonate theory is coming back, to many years out of school. If
Interesting thread ... (and I AM a supporter of modeling) Yet, isn't there a "watch out for" when using large differences of conductor diameters ? (like a 6" vertical and #14 top loading as to the r
Yes, this is a situation to avoid. For a short vertical like the one under discussion, the easiest way to avoid the problem is to model the larger vertical section using 3 or 4 wires the same size a
Yep, that's the main reason Roy included average gain in the windows version, so you could watch for errors. You do have to carefully look for weird results. Turns out average gain works especially
There was an article some years ago in QST I believe that gave some efficiency numbers of top hat loaded low band verticals with different top hat loading configurations. I seem to recall that a coup
The reduction in efficiency is a direct result of the reduction in radiation resistance due to the sloping top hat wires. With lossless ground, there is no reduction in efficiency. I have an inverted
Hi Phil.........Avoid the interfering waves loss of sloping topload wires by adding a topload above your beam. I added a 20 ft aluminum pipe with 80 ft of copper wire in series & zig-zagged the wire
Author: Tony Reynolds" <kb8jvh@reydata.com (Tony Reynolds)
Date: Wed, 13 Feb 2002 18:22:41 -0500
Hi Jerry, 2 new models I built can be downloaded from: http://www.reydata.com/160jvhhorzhat.ez http://www.reydata.com/160jvhslopehat.ez Both are of a 48 foot tall vertical element resonated with 4- 5
No, although it would be much better if the outer ends were connected...especially if the wires had to slope down. That would allow use of shorter wires in the tophat. It should also make a good 80