Ask Michael, KB9VBR: How is the Window Screen Ground Network doing?
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- Опубліковано 14 лип 2024
- A viewer asks: How is the window screen ground plane working out for you. Joe, Travis, and I give an update on the vertical antenna hack that's been sweeping portable operations by storm.
Watch the original window screen video: • Window screen antenna ...
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#Hamradio #AmateurRadio #POTA #ParksOnTheAir #PortableHamRadio #yourquestionsanswered #windowscreen #groundplane #verticalantenna - Наука та технологія
Michael, you are getting famous with the window screen radial idea. I can't wait to try it.
I use to work as an EMI Test and Measurement Engineer for 35 years. I help build a 30m test facility and the outside antenna had what I called chicken wire under the receiving antenna
but much larger than what you show. We ground the outside edges in several places and it allowed us after several test measurements (Site Attenuation) to meet the requirements for a OATS (Outside Area Test Site)
Bronze screen is used a lot on sail boats to provide the ground plane for marine HF radios. 73
I like Mike's REALISTIC VHF/UHF scanner on the shelf behind him. It looks like the PRO-48, one of which I have running on a shelf next to me as I watch this!
That's my old rock box I picked up at a hamfest several months ago. Now I'm on a quest to fill it up with crystals for our local 2 meter repeaters and local analog fire/paging frequencies.
My success so far: Works GREAT on 40m, tunes right up. But when I've switched over to 20m (using the power pole patch cord also debuted by Michael KB9VBR) I struggle to get great swr. Up around 2:1 or just over. Odd given that I'm using the 213 inch whip. But, I'll admit that I need to do more tests. [update, 7.1.23] After spending a week in a vrbo in WI and playing with this configuration, I'm quite happy. Many many thanks to Michael's work and youtube channel for such great suggestions. This is now my favorite WRC configuration.
This past weekend I was boondocking in the Adirondacks of New York State. I setup my brand new 213 inch whip and Sporty Forty coil with screen. At first I used the ground wire from the base to the screen and my G90 did not like that at all. It gave me warnings when trying to tune. Removed ground wire and had a great day. After watching this video I realized I did select aluminum screen with the black coating. I will try to clean a spot of the screen to make a good contact with the ground wire. So I am up in the air if the ground wire is needed but I will be back out this weekend to hopefully activate my first park. Thanks for the videos. KD2UTJ.
Now this gets one thinking. Emergency blankets, aluminum foil, etc…..
So I have been using the window screen antenna arrangement for several weeks now. It works great! Doing multiple park activations has been so much easier. No tangled wires, no fuss. Obviously the rolled up screens take up a bit more physical space, but they are very light and can be slung under your pack like a bedroll. I use two, side by side. I have also lined the edges of the screens with gorilla tape to prevent fraying and poking of the fingers. Maybe(?) the best part is that your antenna footprint is confined to a ~80"x80" space. Very handy in higher traffic areas and much more visible to passers-by than thin wires in the grass. If there is a difference between the screens and a mess of wire radials, I can't tell. I am thinking about changing how I put them on the ground and try to detect any directionality. What if I laid the two down like a landing strip with the antenna on one end? Gonna have to try at some point. Look up NC1F on QRZ for a couple of pictures.
I’d like to learn what you discover if you put the screens end to end.
@@lawrencethompson465 UPDATE: I did a 5 park run yesterday and decided to stop at the Battleship North Carolina (K-6831) on my way home to try out the idea of placing the screens end-to-end under the antenna. I laid the window screens out in a long rectangle ~36”x160”. The screens were laid down such that the long axis ran from ~280 degrees to 100 degrees. The tripod and whip were the WRC “mega” tripod and the WRC 213” whip and were placed at the far east end of the window screen “runway.” Hopefully this would create a situation where some directionality or gain would be achieved in favor of contacts to the west with some loss of same to the north and south. Short answer is, I did not notice any difference.
I have had the good fortune to operate from the radio rooms of the battleship on several occasions. Until the generators for the original transmitters get re-installed (they have been refurbished), we use modern radios on the ship (ICOM 756 Pro 3, and Elecraft K3) along with the original cables, trunking, and vertical antenna of the ship itself. Our local club is very active in volunteering on the battleship and were instrumental in restoring and servicing the ship’s original radio equipment. The point is, I have a good store of contact data from using some fantastic vertical antennas mounted 100 feet in the air over a 729 foot long, 108 foot wide, solid steel ground plane.
If I compare the contact maps of those made from the battleship itself from the ones made by the window screens in the parking lot and those made with this “runway” pattern of the window screens in the same spot in the parking lot, the contact pattern does not seem to significantly change between the three. If there is a noticeable difference as an operator, it seems like I get more close-in contacts operating off the ship than I do on the ground. I’m sure antenna height makes all the difference in that case.
If my null hypothesis was that the “runway” arrangement of the window screens would make no difference in directionality, as measured by contact patterns, then I seem to have failed to find sufficient evidence for H1. That is to say, I found insufficient evidence to say that the “runway” arrangement changes anything. Shorter answer… It did not work. Maybe if you used FT8 or WSPR, you would be able to tease out some sort of difference. My test was a very simple one and not terribly sophisticated. But, in this one circumstance, in this one instance, I did not see the directionality that I had hoped to see. Perhaps others, could try something a bit more sophisticated and get a more telling result one way or the other. Visit my QRZ page and scroll to the bottom to see the contact maps and pictures.
@@NC1F_Matt great write up here and on your QRZ page. Very informative. Thanks!
KQ4IQB
Just saw your reply. Thank you very much for your helpful and interesting reply. Very much appreciate your time in doing so. Also saw your QRZ page. Lots of fascinating and historical information. Likewise appreciate your info on KJ6ER, Greg’s antenna experiments. His emails are chock full of good material plus they work.
if you’re setting up an 80m or 160m dipole, make it a fan dipole for additional bandwidth.
as for the screen edge, clamp (little nuts and bolt) two yard sticks on each of the cut ends. rolling it up would be the length of the yard sticks and it’ll keep the screen straight.
I tried out the window screen idea when you posted your first video on using screens for a ground plane. It is the black coated style. I had pretty poor results. I could hear ok but struggled to get out and struggled to get below 3:1 SWR. I didn't know I needed to sand down to bare metal and your suggestion could (should!) be a game changer. I haven't had a chance to test it yet but I'm so hoping doing that will make the screen mesh idea work and lower my SWR. Fingers crossed, thanks for the tip!
I made one and stapled a couple of 1"x1" to each end and then stapled a pieces of velcro so it stays down, and rolls up (the velcro keeps it rolled).
I've been using window screen since your first video and love it. Works perfectly, much smaller footprint, and much faster to set up than radial wires. Mine too are fraying on some edges. I'm trying to think of a way to reinforce it, but at the price, I could consider it a consumable to replace every x number of months.
Try this on the window screen to save your fingers: In advance, lay it out on on a flat surface and weigh it down to keep it from curling up, then put down an outline of your intended size using silicone sealant. Let it set completely then trim it to size. Put down another bead along the edges to cover the sharp edges and again let it set up completely. Now you have a flexible screen grid that can be rolled and unrolled without needing to pack Band-Aids!
I'm going to have to give that a try sometime.
I used it in my backyard on 20 and got good DX. England, Lithuania, Croatia, Bulgaria, Russia. I am using a 1/4 wave vertical with a stake into the ground. I also used a piece of hardware cloth that I had laying around (careful cause it pokes). I switched to radials using 18ga speaker wire (6 radials) and the SWR improved. The radials are easier to deploy.
I used the platinum coil with aluminum screen on 80m. it tuned to a 1.2 with about 5 or 6 clicks up from bottom. I made a few contacts in other states using js8call. Did stay long, was about midnight 1 am, but I was able to make contacts. still needs more testing. but worked
I’ve put grommets in the corners and one in the centre of my stainless steel window screen. One of the main reasons for the grommets was due to my screen being poly coated. I singed the coating by the grommet holes with a lighter before installing the grommets to get better conductivity to my antenna ground.
Sounds like an interesting concept for a ground plane. If you want a longer lasting grid for a near-permanent or permanent grid, a section of cattle panel might work well. It is a fairly stout wire gauge.
While we're testing chicken wire vs window screen, how about things like a roll of fence row, or a hog confinement panel?
Using 22 gauge wire I use 4 bundles of 5 2 meter lengths wire on alligator clips… to attach to my ground stake 1/4 “ bolts.. quick 20 meter counter poise for my vertical. Easy set up to spread out a great pattern
I've have been using the window screen as in your video on my WRC but for 80m I found that I needed 2 rolls of screen to get a good match.
Refrigerator condenser coil works well. A little more of a hassle to transport around though.
Michael and Joe should do a tour. Seriously, do Huntsville, Xenia and Hamcation. Your bit would be better than any of the forums.
I have talked about using s ground screen for years, and have gotten NOTHING but NEGATIVE reactions that are at times are just short of Physical violence. After seeing your first video my XYL( a ham as well) has now said I can install a vertical with a window screen under it. I will be installing a 6BTV on the roof( only good option) with 100 feet of 60 inch wide window screen under it. The roof ridges form a wide " H " ( >---< ) pattern. If there is good performance from the screen I will seal it to the roof with brush grade roof seal.
A ground screen would be a good option for putting a vertical on the roof. I don't know why so many people doubt its effectiveness, broadcast stations have been doing the same thing for years and it works off the same principle as using your vehicle as a ground plane. I do think that 100 feet of screen may be overkill, though and you should be able to get excellent low band performance with a smaller number. Check out the original Robert Sherwood article that was the basis for my experiments, it has information you will find useful: ia903006.us.archive.org/12/items/hamradiomag/ham_radio_magazine/Ham%20Radio%20Magazine%201977/05%20May%201977.pdf
@@KB9VBRAntennas It's not that they doubt the effectiveness of the screen, it's more of they think anything I talk about will not work. Yet wait a while and you see them using and doing things they told me that doesn't work. So I left the local club about 15 years ago.
Threw some stainless screen in the truck today to try..but just had the sporty 40 and whip mounted to my truck..so didnt try it...yet. ..soonly however. 73, Mike W2GR
I'm so looking forward to trying this, thanks! Do you guys think the configuration of the screen, and how much you use, might make a difference? My obsessive self immediately thinks of arranging lengths of screen in a pattern of 3, 6, or even 8 lengths of screen radiating out from the centre. But would that even make a difference? Or is the fact that there's a lot of wire in even a single length of screen enough to make such considerations moot? Cheers!
Would a 16 x 4 Cattle panel be good for home base use, or cut into 4 foot long sections for portable use.
Good stuff. And Joe looks good with a beard. He should keep it. U-rah-rah
Try using a framed window screen maybe? It would be smaller, but no rough edges.
It's my guess if you double the length of the screen (attach 2 screens length wise for both sides. That should help with 75 and 80 meters as long as the antenna is capable of the lower bands.
I agree, I'd also double the number of screens for the lower bands.
Would it be possible to put the Aluminum Duct Tape along the edges to keep it from fraying?
I believe I have seen VK3YE using aluminum foil as a ground plane, that would work as well, he put tape around the edges I seem to recall, al ve3gam
I’ve been following this window screen series of videos. Will be interested to see what it does on 80 meters and wonder how size of the screen impacts performance. I have ordered a roll of screen that is 200” in length, just over 16 ft and 47” wide. Thoughts?
The screen will work on 80m, Dave KZ9V, has used it along with a 67 foot piece of wire as an 80m 1/4 wave vertical. The Sherwood article suggests that for the lower bands, more screen is better. ia903006.us.archive.org/12/items/hamradiomag/ham_radio_magazine/Ham%20Radio%20Magazine%201977/05%20May%201977.pdf
I would think screen would be better compared to chicken wire as there would be much more area for skin effect with window screen.
test many screens for 1 lambda space around antenna (10x10m for 28mhz)
What about safety blankets ? They are just a very thin metallic sheet, right ? 73 de SV4RIN
If you can achieve good electrical conductivity from the ground side of the antenna to the blanket or other material, then it should work.
I think I heard one of you suggest going “full Mythbuster” on this. So will chainlink be tested?😂😂😂😂😂
How large is the screen?
The screen I'm using is 36x84 inches. Here's the original video I referenced that gives all the details: ua-cam.com/video/UadUg5H8KO8/v-deo.html
Anyone around NW Georgia that does pota?
I bought one it works great 👍 thanks Michael for all the videos Sal KM4PPV!