[600MRG] 600MRG Digest, Vol 72, Issue 14

[Roger Graves]

Ken,

1) For in-ground radials “resonant” does not really apply.

2) No deleterious effect. Generally speaking, more short radials are better than not adding more.

3) Most of us are not so lucky to have a big empty field to put our verticals in. Bent radials are better than no radials.
There are guidelines for length/number of radials, but I will give a few of my impressions.
a) making radials longer than the vertical height of the vertical is not anywhere near as helpful as getting them out to that distance, so more than 66 ft is probably not going to be worth the effort, even for 630 mtrs, with a 55 ft  vertical. With a trap vertical, your 20 mtr height is about 16 ft.

b) Add radials until the ends are separated by 0.05 wavelength. For example, if you have 1/4 wave long radials (.25 WL), the circle circumference is about 1.5 WL, so you would need 30 radials to get to that. Beyond that number there is not much benefit. So, for 20 mtrs, 30 16 ft long radials, etc. If you can get 30 66 ft long radials that would be probably be the best you can do for a 55 ft vertical. I suspect you are thinking something more limited. Given you have 4 now, doubling to 8 would make a difference I should think. To improve on that you need to go to 16, then 32.

c) connect the ends together, this will help on the low bands.

d) For 160 and 630 you will need top loading, like an inverted L or a T. In this case, I would suggest making sure you have one radial as long as each top wire directly underneath it to form the other side of the capacitor. My 630 mtr antenna, in my city lot, is a 30 ft vertical wire, then a 130 ft (somewhat) horizontal wire running around the fence line with a ground wire underneath it, plus as many short radials as I have had the energy to bury in the lawn.

Just some thoughts for you to consider. Others may have different views.

Good Luck and Have fun!

Roger


On Apr 23, 2017, at 10:00 AM, 600mrg-request at w7ekb.com wrote:

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> Today's Topics:
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>   1. Verticals and radials.... (Kenneth G. Gordon)
> 
> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
> Subject: [600MRG] Verticals and radials....
> Date: April 22, 2017 at 7:37:54 PM PDT
> To: 600MRG at w7ekb.com
> 
> 
> I am finally going to add at least 20 radials to the HF all-band 55' vertical I have been using 
> for a number of years.
> 
> /(Sarcasm on).At the present time, I have only 4 ea 66' long radials laid on the ground. The 
> antenna is not very efficient (/sarcasm off.)
> 
> The vertical is what amounts to 1/2 of a W3DZZ all-band trap dipole (one trap in each side), 
> set vertically. It exhibits a 2:1 or less SWR on 80, 40, 20, 15 and 10 meters, and I use it with 
> a coupler on 60, 30 17, and 12 meters also.
> 
> So, my questions:
> 
> 1) Do I need to make all the radials resonant at some ham band, or does it really matter?
> 
> 2) What deleterious effects will there be if the radials are shorter than a resonant length?
> 
> My yard is not "round", the antenna is NOT in the center of the yard, my house is "in the 
> way" over at least 1/3 of the radius around the vertical, and I have read somewhere that if 
> one wishes one's vertical to operate at peak efficiency, one should "copper plate" the 
> ground under and around it....but how far "out"?
> 
> Enquiring minds need to know.
> 
> Oh. One more thing: I also use it on 160 by using a base-loading coil, and have planned to 
> use it on 630 meters with another loading coil.
> 
> Advice? Suggestions?
> 
> Ken W7EKB
> 
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