It's an old concept. I went to the US Army electronic countermeasures (ECM) school over 40 years ago. We played with powerful radio jammers. Up to 2.5kw into a vertical or a long periodic array. We had to put out the counterpoise before putting up the antenna. It had a hole in the middle for the antenna mast to be centered in. It was a mesh that felt like a strong yet flexible plastic but it also contained a metal center. Most likely copper. The number two rule was not to stand inside the counterpoise when we were transmitting. Number one rule was not to touch the antenna when transmitting.
I had been toying with the idea of some sort of mesh as a ground plane for years. Kind of limited for opportunities to experiment. Nice to see I was not crazy to think it was a good idea
Dolomite, ground up it is used in fish tank filters. Interesting trivia. I purchased the metallic fabric and will attempt to use my Chameleon MPAS2 with the 17 foot whip again. I had poor results with radials in front of my QTH, so bad I put that antenna up where I cant find it. You have demonstrated that it can work. I have poor soil in NC. 73
For non-resonant antennas, the feed point impedance is just about anything other than 50 ohms. And it would vary all around the Smith chart based on frequency. This impedance variation also applies to the grounding point of a monopole vertical. In other words, at a frequency where the antenna happens to be very high impedance, the ground currents may be extraordinarily low (with commensurately very high voltage). So a capacitive plate (as used in this video) would presumably do great in those particular circumstances. At other (e.g. lower) frequencies, the antenna may approach a dead short, and you'd better lay-out a zillion radials, or be halfway into the sea. An example you'd already know: I think it's well known that an End Fed Half-Wave antenna, being high impedance and requiring a high-ratio transformer, they can get away with a very minimal grounding solution, because there's hardly any current at the feed point, self-evidently applicable to both the driven element and ground. This is merely conceptual, but might help to reduce the mystery. A very wise man once said, "RF wouldn't be so mysterious if it were purple."
we have doing some serous reasearch and gathering data on window screen as a ground plane. We are not ready to publish just yet, but look for it in QST sometime this year N6JAI
So Michael in the 40-meter band you had 3.8 SWR I'm curious that you do the experiment with two window screen and get better results in this band Thanks for sharing / 73 CR7BDO
I didn't check the SWR for the 80m band, but I'm guessing it would be just as bad. Adding another screen would add more capacitance and most likely lower the SWR for 40m.
I love the MPAS 2.0, I have the CAP HAT. Works great on 20,17,15,12 and 10m, 40 isn't the best but I can still get around Europe with 100 Watts. On 20m I've got to Australia a couple of times, but not usually on at the right time for Australia. I thought about putting a external tuner at the antenna but then I realise that I'd only be doing that for 80,40m and the antenna is never going to be great on 80 and 40 and SWR is reasonable on the other bands so it would be a waste. I have the MPAS 2.0 set up on the front lawn and use it in the sitting room to scan the bands when too lazy to go to the shack, it works pretty well but I would like something better for 40m. Perhaps even a 5BTV but for portable ops the MPAS 2.0 is really great.
Thanks for the video. I immediately bought a 36 X 84 aluminum screen to give this a try. I am new to portable and would like to start doing POTA. I tried to tune my WRC Mini TIA with the antenna sitting directly on the screen, hoping that the 3 points of contact the aluminum tripod had with the screen would be sufficient. Unfortunately, it was a no-go. I wasn't able to tune any band to less than 6 SWR. Using
Setting the legs of the TIA base will provide enough continuity for the screen to work as a ground plane. If you are getting a consistent 6:1 SWR, I’d check your coax cable connections. In my experience, an SWR at that level usually is related to poor or broken connection.
The coax checked out fine. Same coax I used when I installed the radials and got consistently low SWR. I appreciate your speedy response, and enjoy your videos. I also have one of your copper j-poles.@@KB9VBRAntennas
Another thought, is the screen you are using bright aluminum or is it the black stuff? If the screen is dark colored, you will need to scrape off a bit of the coating in order for the antenna to make electrical contact. You may also need a short jumper from that contact point on the screen to the base of the antenna.
@@KB9VBRAntennas it is bright aluminum. I am going to make a jumper to see if that resolves the problem. I appreciate your continued thoughts on this problem and will let you know if the jumper works.
I just had an interesting development. I moved the screen and antenna 15 feet. Now it tunes beautifully! I cannot see anything different in the environment around the antenna, but there was obviously something interfering with tuning. @@KB9VBRAntennas
Thanks for the history on the rock. What are you using for loging? I have not been on the air since 82-83, setup a new shack about 2-3 years ago but still have not keyed up. I feel like a novice after being off for years, boy how things changed. lol
This looks very interesting but one additional thing I'd be interested in is have you tried a multimeter to measure the resistance across the ends along the mat?. I like the idea of the large area/large capacitance coupling to earth but I'm not sure about how resistivity/lossy the fine steel mesh of the screen might be (would be interesting to look at it with a thermal camera on TX). Sometimes "good" results with easy tuning can be indicated when things are lossy rather than efficient. Sometimes high Q very peaky & fiddly tuning indicate better performance.
The metal screen material we used is aluminum, and I have measured the end-to-end resistance with an ohm meter. The 80-inch aluminum screen resistance is zero. KZ9V
I looked into this with interest when I saw the video come out about using screening or mesh with a vertical antenna. I was toying with the idea of putting mesh in my attic and mounting a verical on the roof. I am not sure how this will work, but for the cost of the screen, it might be worth it.
I believe I received a few comments from others that said using a screen with their attic antennas did work. Screen is cheap so you aren't out much by trying.
The weekend QSO action was rough indeed. I tried the screen idea with a ground mounted Yaesu ATAS 120A. I experienced no luck with the automatic tuning via the FT891. The ATAS likes traditional radial wires. I'm hoping to see more results. Good or bad. This is a brilliant idea. I'll test this with the WRC next. Thanks! 73
That's interesting. I'd think that the ATAS would be receptive to this as its designed to be mounted on a vehicle. But not having one, I don't have the means to test it. Let me know how it works on the WRC for you.
Has the window screen been tried with a multi band fixed vertical? Cover the screen with ivy vines (camouflage) and I think it would work and less hassle laying out zillion radials and hopping the lawn mower doesn’t get tangled up in radials.
Yes the screen will work with a fixed vertical antenna. In that case, with permanent mounting, I'd use a more substantial screen, like hardware cloth that has welded holes, and use 60 - 120 square feet of material to improve low band performance.
What was the antenna used in the first video on Mesh screen w/ David? Can you recommend an antenna for mesh on 6m? as here in my home state CO, can't get a good signal using mesh screen on 6m, although works fine on lower bands such as 15m & 40m. Just on 10 watt w/ X6100. Thanks 73!!!
The aluminum screen ground plane works great on 6-meters. My guess is you just haven't been lucky enough to be using it during one of the rare 6-meter band openings. 6-meters is very unpredictable here in Wisconsin. KZ9V
You got me today at +43 on FT8 (20m - w9fff). INSANE. I am on a 4:1 with some amount of wire in the attic and was using 30 watts. Were you using the Screen Ground Counterpoise today?!
Unfortunately no. I was at home fine tuning my FT8 setup. I recently picked up a Digirig Mobile interface and I was at home getting my settings dialed in. FT-891, 30 watts, end fed random wire antenna is what you heard. I’ll make a note to send you a card and sticker.
Good morning from Central Florida, and I tried your configuration, it only worked half way...I am using a fire stick set up in the middle of my living room...it worked in that before it wasn't calibrating and I got it down to swr 2.1 and I tried to get to 1.1 and no such luck, it went back up in the red and since then I can't get back to the 2.1 ..PS I am a CBer and not a hamster
I'm using a 36x86 piece of bright aluminum window screen. The actual dimensions aren't terribly important. But we have found in the previous video that adding more screen does help with performance.
Not plastic, but bright aluminum window screen. I use a 36x84 inch piece. Here's the original video with all the details: ua-cam.com/video/UadUg5H8KO8/v-deo.html
Yes. Ground mounted radial networks depend on surface area to work. You can use a few long radials or many short radials with similar results. A screen maximizes the surface area in a smaller space, providing equivalent results.
With a screen-mesh area of 10 to 20 times what you have, you might have a counterpoise that would be an improvement over several radials. I strongly doubt the size you used makes any difference at HF.
You are most likely correct as the article I referenced came to the same conclusion. We were looking for equivalent performance with a faster setup for portable operation. I think we achieved that.
Possibly. In using the smaller screens, I have not noticed any appreciable directivity with them. But as you start adding more and more, you can steer the signal a little bit.
Possibly. I checked on a map and the long dimension of the screen was oriented from Southwest to Northeast. At my latitude, Vermont is due east and Alabama is due south. Would that mean that the bulk of my contacts were broadside of the screen?
Our club has a BB7V. It was donated by a ham that was thinning out his collection. The antenna works well enough, I've set it up and used it for a few special events and field day and made plenty of contacts with it. It's advertised as a no ground radial antenna and that's how we deployed it, but I think it would work better with a radial network. The only thing I don't like about it was the twist-lock assembly of the antenna sections. We converted our to screws and hose clamps which is more secure.
Have you had any issues with collapsing the BB7V..I have a section that won't collapse..Diamond fixed it once and now a second time...want me to return it again. Paul K1YOU
I referred back to the log for this activation and made a total of 38 contacts. 9 were on 40m and 29 on 20 meters. As I recall, band conditions were not very good that day and 40 meter performance was lacking. It was also mid-day which hampered 40 meters a bit. On a technical level, it does work, the window screen provides a good counterpoise for the antenna. But as for practicality? It's still a non resonant antenna vertical antenna with a 5:1 transformer, so expect some sort of losses on the lower bands.
You bring up an interesting point. While the gold standard is NATO phonetics on the airwaves, quite often amateur operators will slip into another version of the phonetic alphabet to either help break a pileup or to get the information through in tough conditions. For example: if conditions are bad, I have a very hard time discerning between Alpha and Oscar, especially if the station has an accent. But if they use America or Ocean when I ask for a repeat, I will instantly make the distinction and correctly copy their callsign. It's good to know that alternate versions of phonetic alphabets exist and to use them when the need arises.
According to the article that I cite in my video, the gains are marginal until you reach about 60 square feet of screen. Then after that point, adding more screen makes a big difference, especially on the lower bands. For reference, one 36x84 inch window screen is about 21 square feet.
It's an old concept. I went to the US Army electronic countermeasures (ECM) school over 40 years ago. We played with powerful radio jammers. Up to 2.5kw into a vertical or a long periodic array. We had to put out the counterpoise before putting up the antenna. It had a hole in the middle for the antenna mast to be centered in. It was a mesh that felt like a strong yet flexible plastic but it also contained a metal center. Most likely copper. The number two rule was not to stand inside the counterpoise when we were transmitting. Number one rule was not to touch the antenna when transmitting.
I struggled on Sunday too, but pushed through. POTA on!
I had been toying with the idea of some sort of mesh as a ground plane for years.
Kind of limited for opportunities to experiment.
Nice to see I was not crazy to think it was a good idea
Dolomite, ground up it is used in fish tank filters. Interesting trivia. I purchased the metallic fabric and will attempt to use my Chameleon MPAS2 with the 17 foot whip again. I had poor results with radials in front of my QTH, so bad I put that antenna up where I cant find it. You have demonstrated that it can work. I have poor soil in NC. 73
For non-resonant antennas, the feed point impedance is just about anything other than 50 ohms. And it would vary all around the Smith chart based on frequency. This impedance variation also applies to the grounding point of a monopole vertical. In other words, at a frequency where the antenna happens to be very high impedance, the ground currents may be extraordinarily low (with commensurately very high voltage). So a capacitive plate (as used in this video) would presumably do great in those particular circumstances. At other (e.g. lower) frequencies, the antenna may approach a dead short, and you'd better lay-out a zillion radials, or be halfway into the sea. An example you'd already know: I think it's well known that an End Fed Half-Wave antenna, being high impedance and requiring a high-ratio transformer, they can get away with a very minimal grounding solution, because there's hardly any current at the feed point, self-evidently applicable to both the driven element and ground. This is merely conceptual, but might help to reduce the mystery. A very wise man once said, "RF wouldn't be so mysterious if it were purple."
That's a great description of what's happening, and a good example of Ohm's Law at work.
I love the screen idea Michael! I will be stopping by the hardware for a screen on the way to my next activation.
I’m curious about what would change if you put the window screen in the middle and stick the spike thru it.
I don't think it would change things much at all. Maybe if the screen was longer, you could use its orientation to achieve some directivity, though.
we have doing some serous reasearch and gathering data on window screen as a ground plane. We are not ready to publish just yet, but look for it in QST sometime this year N6JAI
So Michael in the 40-meter band you had 3.8 SWR
I'm curious that you do the experiment with two window screen and get better results in this band
Thanks for sharing / 73
CR7BDO
I didn't check the SWR for the 80m band, but I'm guessing it would be just as bad. Adding another screen would add more capacitance and most likely lower the SWR for 40m.
@@KB9VBRAntennas yes Michael I have the same opinion... but nothing like trying it ... antennas, each is a case 😉 Many thanks / 73
That last contact had me laughing.
That's what happens when you leave the mobile on in the vehicle when you go out to try to catch some VHF contacts across the lake.
Rough day for a POTA. That storm was intense 😳
At least I got lunch out of it.
I’m looking forward to trying the screen
Definitely not the best day to be out there but you proved that contacts are still possible under such conditions. U-rah-rah
That is true, and with a 'compromise' antenna too.
I love the MPAS 2.0, I have the CAP HAT. Works great on 20,17,15,12 and 10m, 40 isn't the best but I can still get around Europe with 100 Watts.
On 20m I've got to Australia a couple of times, but not usually on at the right time for Australia.
I thought about putting a external tuner at the antenna but then I realise that I'd only be doing that for 80,40m and the antenna is never going to be great on 80 and 40 and SWR is reasonable on the other bands so it would be a waste.
I have the MPAS 2.0 set up on the front lawn and use it in the sitting room to scan the bands when too lazy to go to the shack, it works pretty well but I would like something better for 40m. Perhaps even a 5BTV but for portable ops the MPAS 2.0 is really great.
Wish you would of asked them which was better. With or without
Thanks for the video. I immediately bought a 36 X 84 aluminum screen to give this a try. I am new to portable and would like to start doing POTA. I tried to tune my WRC Mini TIA with the antenna sitting directly on the screen, hoping that the 3 points of contact the aluminum tripod had with the screen would be sufficient. Unfortunately, it was a no-go. I wasn't able to tune any band to less than 6 SWR. Using
Setting the legs of the TIA base will provide enough continuity for the screen to work as a ground plane. If you are getting a consistent 6:1 SWR, I’d check your coax cable connections. In my experience, an SWR at that level usually is related to poor or broken connection.
The coax checked out fine. Same coax I used when I installed the radials and got consistently low SWR. I appreciate your speedy response, and enjoy your videos. I also have one of your copper j-poles.@@KB9VBRAntennas
Another thought, is the screen you are using bright aluminum or is it the black stuff? If the screen is dark colored, you will need to scrape off a bit of the coating in order for the antenna to make electrical contact. You may also need a short jumper from that contact point on the screen to the base of the antenna.
@@KB9VBRAntennas it is bright aluminum. I am going to make a jumper to see if that resolves the problem. I appreciate your continued thoughts on this problem and will let you know if the jumper works.
I just had an interesting development. I moved the screen and antenna 15 feet. Now it tunes beautifully! I cannot see anything different in the environment around the antenna, but there was obviously something interfering with tuning. @@KB9VBRAntennas
Thanks for the history on the rock. What are you using for loging? I have not been on the air since 82-83, setup a new shack about 2-3 years ago but still have not keyed up. I feel like a novice after being off for years, boy how things changed. lol
For my Parks on the Air activations I use Hamrs www.hamrs.app
@@KB9VBRAntennas Thanks for the link.
This looks very interesting but one additional thing I'd be interested in is have you tried a multimeter to measure the resistance across the ends along the mat?. I like the idea of the large area/large capacitance coupling to earth but I'm not sure about how resistivity/lossy the fine steel mesh of the screen might be (would be interesting to look at it with a thermal camera on TX). Sometimes "good" results with easy tuning can be indicated when things are lossy rather than efficient. Sometimes high Q very peaky & fiddly tuning indicate better performance.
The metal screen material we used is aluminum, and I have measured the end-to-end resistance with an ohm meter. The 80-inch aluminum screen resistance is zero.
KZ9V
I looked into this with interest when I saw the video come out about using screening or mesh with a vertical antenna. I was toying with the idea of putting mesh in my attic and mounting a verical on the roof. I am not sure how this will work, but for the cost of the screen, it might be worth it.
I believe I received a few comments from others that said using a screen with their attic antennas did work. Screen is cheap so you aren't out much by trying.
Have you thought of using copper shielding as a ground? Might be a worthwhile look into.
The weekend QSO action was rough indeed. I tried the screen idea with a ground mounted Yaesu ATAS 120A. I experienced no luck with the automatic tuning via the FT891. The ATAS likes traditional radial wires. I'm hoping to see more results. Good or bad. This is a brilliant idea. I'll test this with the WRC next. Thanks! 73
That's interesting. I'd think that the ATAS would be receptive to this as its designed to be mounted on a vehicle. But not having one, I don't have the means to test it. Let me know how it works on the WRC for you.
@KB9VBR Antennas Followup: I found some spare time today for experiment action. The WRC mini with the screen tunes up perfectly for me.
Has the window screen been tried with a multi band fixed vertical? Cover the screen with ivy vines (camouflage) and I think it would work and less hassle laying out zillion radials and hopping the lawn mower doesn’t get tangled up in radials.
Yes the screen will work with a fixed vertical antenna. In that case, with permanent mounting, I'd use a more substantial screen, like hardware cloth that has welded holes, and use 60 - 120 square feet of material to improve low band performance.
What was the antenna used in the first video on Mesh screen w/ David? Can you recommend an antenna for mesh on 6m? as here in my home state CO, can't get a good signal using mesh screen on 6m, although works fine on lower bands such as 15m & 40m. Just on 10 watt w/ X6100. Thanks 73!!!
The aluminum screen ground plane works great on 6-meters. My guess is you just haven't been lucky enough to be using it during one of the rare 6-meter band openings. 6-meters is very unpredictable here in Wisconsin.
KZ9V
@@davewhite7679 Thanks David!!! patiently waiting for 6m band opening 🙃😇🙂
I think I might try this with a JPC-12.
You got me today at +43 on FT8 (20m - w9fff). INSANE. I am on a 4:1 with some amount of wire in the attic and was using 30 watts. Were you using the Screen Ground Counterpoise today?!
Unfortunately no. I was at home fine tuning my FT8 setup. I recently picked up a Digirig Mobile interface and I was at home getting my settings dialed in. FT-891, 30 watts, end fed random wire antenna is what you heard. I’ll make a note to send you a card and sticker.
I would have liked to see the antenna characteristics before adding the screen for a comparison
Good morning from Central Florida, and I tried your configuration, it only worked half way...I am using a fire stick set up in the middle of my living room...it worked in that before it wasn't calibrating and I got it down to swr 2.1 and I tried to get to 1.1 and no such luck, it went back up in the red and since then I can't get back to the 2.1 ..PS I am a CBer and not a hamster
It might be interesting to do a POTA with a QRP radio.
How would using some steel landscaping staples improve the coupling to earth?
THANKS AND 73
What was the length and width of the screen wire? Also a headphone would probably had helped you I think
I'm using a 36x86 piece of bright aluminum window screen. The actual dimensions aren't terribly important. But we have found in the previous video that adding more screen does help with performance.
It works really well honestly. I think that's been proven. I wouldn't change it
As newbie a question: what material is that " windows screen " a piece of plastic or is there more in it ?
Not plastic, but bright aluminum window screen. I use a 36x84 inch piece. Here's the original video with all the details: ua-cam.com/video/UadUg5H8KO8/v-deo.html
@@KB9VBRAntennas Thank you, it looks very interesting. Wish you a lot of succes and fun with the hobby
Am I understanding the sole benefit here: a smaller footprint that equates to several longer radials?
Yes. Ground mounted radial networks depend on surface area to work. You can use a few long radials or many short radials with similar results. A screen maximizes the surface area in a smaller space, providing equivalent results.
With a screen-mesh area of 10 to 20 times what you have, you might have a counterpoise that would be an improvement over several radials. I strongly doubt the size you used makes any difference at HF.
You are most likely correct as the article I referenced came to the same conclusion. We were looking for equivalent performance with a faster setup for portable operation. I think we achieved that.
I'm only technician class, but I'm going to try this once i can make a metal base to my J-pole and I'm out doors. 73
I would get another screen and place it on top of the other to form a cross. Better all around circular output.
Possibly. In using the smaller screens, I have not noticed any appreciable directivity with them. But as you start adding more and more, you can steer the signal a little bit.
Would copper screen offer any benefits? And YES I do know it costs more.
Slight but more corrosion
It's possible, but I think the improvement would be slight.
IT LOOKS TO ME THAT THE COUNTER POISE WAS DIRECTIONAL TO ONE SIDE OF THE SCREEN. IM GOING TO TRY THIS FROM CENTER MASS.
Possibly. I checked on a map and the long dimension of the screen was oriented from Southwest to Northeast. At my latitude, Vermont is due east and Alabama is due south. Would that mean that the bulk of my contacts were broadside of the screen?
How do think with the Diamond BB7V
Paul K1YOU
Our club has a BB7V. It was donated by a ham that was thinning out his collection. The antenna works well enough, I've set it up and used it for a few special events and field day and made plenty of contacts with it. It's advertised as a no ground radial antenna and that's how we deployed it, but I think it would work better with a radial network. The only thing I don't like about it was the twist-lock assembly of the antenna sections. We converted our to screws and hose clamps which is more secure.
Have you had any issues with collapsing the BB7V..I have a section that won't collapse..Diamond fixed it once and now a second time...want me to return it again.
Paul K1YOU
How does it work on 40 meters?
I referred back to the log for this activation and made a total of 38 contacts. 9 were on 40m and 29 on 20 meters. As I recall, band conditions were not very good that day and 40 meter performance was lacking. It was also mid-day which hampered 40 meters a bit. On a technical level, it does work, the window screen provides a good counterpoise for the antenna. But as for practicality? It's still a non resonant antenna vertical antenna with a 5:1 transformer, so expect some sort of losses on the lower bands.
3:13 contact uses the word 'radio' for the 'R' in his call sign...incorrect phonetic, should have said 'romeo'...just something I noticed.
"N4CPR, that's Naughty Four Czar Pneumonia Radiopharmaceuticals..."
You bring up an interesting point. While the gold standard is NATO phonetics on the airwaves, quite often amateur operators will slip into another version of the phonetic alphabet to either help break a pileup or to get the information through in tough conditions. For example: if conditions are bad, I have a very hard time discerning between Alpha and Oscar, especially if the station has an accent. But if they use America or Ocean when I ask for a repeat, I will instantly make the distinction and correctly copy their callsign. It's good to know that alternate versions of phonetic alphabets exist and to use them when the need arises.
W5CR = whiskey 5 Contest Radio or Chocolate Rabbit always worked 😉
Here, your like and subscribe, now, try to smile a little more, you are so serious!
Catch out livestream every 1st Thursday of the month. We really let things go then.
This guy reminds me of Louis Litt
Why not mount that compromise aerial to your car for a massive improvement......dont waste time sticking it in the ground.
Ok so let's get greedy would 2 screens be even better?
According to the article that I cite in my video, the gains are marginal until you reach about 60 square feet of screen. Then after that point, adding more screen makes a big difference, especially on the lower bands. For reference, one 36x84 inch window screen is about 21 square feet.
You need to bury the screen....
Why?
The park ranger is going to blow a fuse if he sees you plowing a metal screen into his park...
KZ9V
@@davewhite7679 Well, in that case if you have picky ranger (hi hi), then put metal tent stakes in a variety of positions...
I didn’t know Rachel Levine was a ham.