[PPRAANet] Ham Radio Tech: Ground Screens–the “Magic Carpet”?

[John Bloodgood]

I have used mesh/screen before. It can work really well.

Ward addresses one of the most common misperceptions about radials for verticals – that they have to be resonant or cut for a certain band. I have seen many people make four radials four 80 meters, four for 40 meters, four more for 20 meters, and four more at 10 meters.  There is no need to do this.  Generally, just make them ¼ wavelength of the lowest frequency you intend to operate on.  If you can’t make them that long, then make them as long as you can.

Ward says you need at least 16 radials… well, 16 is about where you hit a level of diminishing returns for verticals on 80 meters and higher frequency bands.  If you can only do 12, you will be fine.  I would say 8 is about as low as you want to go, though I have used 4 quite successfully.

To reduce tangling of radials, I have a small aluminum sheet metal plate with 5 thumbscrews & wingnuts. My radials are in groups of 4 crimped to a terminal lug – breaking into small groups means less tangling and you can “comb” it out easily with your fingers. I have 4 such groups for 16 radials. The wire is a very flexible automotive wire and does not have to be very heavy gauge – the current per radial will be pretty low for 100 Watt rigs. The 5th thumbscrew & wingnut is for feed point attachment to the coax.

A helper to get the radials correct is I have a piece of paracord that is cut to the correct distance between the ends of the radial wires.  For example, if your radials are 35 ft long for 40 meters, the spread will be about 13 ft 8 in.  Having a piece of paracord or wire that length allows me to easily and quickly get the radials pretty evenly spread.

When using mesh, a couple things to keep in mind.  First, sharp points. There can be a lot of little pointy things to stab, slash and tear your skin and clothing. You probably want to wear leather work gloves.  The other then is degrees of coverage. Let’s say you have a 2 ft wide roll of wire fencing and you lay it out in a big X.  That will leave about a 47 ft gap out at the ends of a 35 ft long radial.  That has some effect on the radiation pattern. It may not make a huge difference , but the more degrees of coverage you can get, the more even the pattern will be. Like regular wire radials, no need to go bonkers though, 4 directions will work well, 8 may work better.  What the point of diminishing returns is, I can’t say – it may be 4, it may be 8, Ward indicates around 6.  Again, it doesn’t have to be very heavy gauge stuff.  I haven’t played with the size of the grid to see if 1/4 inch, 1 inch, 2 inch, or 4 inch grid spacing has any noticeable effect.

Just my personal observations, your mileage may vary.




John Bloodgood, KD0SFY

From: Derek Brown<mailto:DBrown719 at outlook.com>
Sent: Friday, September 15, 2023 8:53 AM
To: PPRAANet at mailman.qth.net<mailto:ppraanet at mailman.qth.net>
Subject: [PPRAANet] Ham Radio Tech: Ground Screens–the “Magic Carpet”?

Good article / easily digestible. I've recently come across folks doing this just below the surface on permanent installs as well. On a normal POTA I'm going to still use my deployable wire radial field. If I were camping somewhere for a week or back yard experimenting I'd like to try this.

https://www.onallbands.com/ham-radio-tech-ground-screens-the-magic-carpet/

Derek / K0ATV


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