This will sound goofy but I was astounded by how much this has increased my signal strength with an inverted L antenna on the top AM broadcast band. I found a few bundles of tractor mesh green fence, not sure what wire it's made of but assuming aluminum or something similar. The coating that is green on it is like wire plastic coating in that it's really easy to scrape off with a knife and pull the plastic off to find bare metal.
I've been wanting to upgrade my ground radials for my AM antenna because I know it's a major part of the antenna system and with low HF going into MW frequencies the ground system for a monopole can make all the difference. But how much of a difference?
I took over 60' x4 of CAT5 wire and stripped each wire down to copper and used about 4 of those around the base of the antenna stretched out to where I could and either buried it or placed it where not noticeable. Thanks to the Internet installer who accidentally left a 700' box behind hehe, but that did help a lot for inverted L antenna efficiency. Probably doubled my signal strength across town using the same power.
After getting 50' or so of tractor green fence, something like 4' by 50' and stripping some of the green plastic off in multiple places to make multiple wired connections for redundancy, rolled it out lengthwise at a slight angle to the horizontal portion of my inverted L up in the air but well out of sight and will self bury in time...
Holy crap! My signal improved tremendously. I'm not talking about slight increase, I am talking about using this antenna now as an antenna for receive and it overpowers my DX398 radio to the point where I need to turn down RF gain. Local stations have images up and down the band w/o doing so. Definitely going to need a high pass BC band filter now if I use this for receive.
Transmission? I was blown away. ERP is way up compared to those long and short radials I added. Something about a mesh of wire laid flat rivals any radial wires.
Name of the game here is if you want a killer signal on the low HF bands or mediumwave, get some chicken wire or tractor fence and lay that shit out where you can around the vertical portion of the areal. It can take your signal from a peanut to a blowtorch!
This stuff is your best friend if setting up a vertical low band HF or mediumwave antenna. Scrape off the plastic on each strand and multiple wrap wire to each and interconnect to your RF ground point, probably near your ground rod or RF coax antenna point. Lay out flat, use lawn staples or hide the rolled out portions under property. Cheapest best radials you can ever ask for!
I got mine for free. Just need to keep an eye out for things like this laying in the trash or ask around, someone probably knows someone who has some in a garage or barn. Be nice and offer a few bucks or whatever. Many antenna parts and sometimes even whole antennas can be found on old properties or barns, a little talk goes a long way!
Post by ogrevorbis on Sept 5, 2019 14:35:15 GMT -6
Glad you posted this. I was thinking about buying some more electric fence wire because a few of my ground radials have broken off somehow. Well, now I'm definitely going to try this. I kind of disregarded it in the past because I knew that it would make it a hassle walking around the base of the antenna. I have to do some shrub pruning because my antenna is in a field and a bunch of stuff has grown up around the base. Now I know it's worth it to chop those plants down so I can lay this stuff out. I'll try to find the variety without the plastic.
I've recently been doing a ton of experiments on the AM band. The shunt coil on my antenna has proven to need adjustments to tweak the frequency after rains, so I purchased a roller inductor that I am going to enclose in a weather proof case. If anyone's curious, I needed a 7uH inductor to get a good SWR on top band AM. I am a bit concerned about the contact area of the wheel getting too hot. I may end up needing a heavier-duty one with a wiper instead of wheel for better contact. I've pretty much quit with FM entirely just to be safer, plus AM is a lot more fun and mysterious. In the evenings, you may occasionally hear my signal on 1710 AM in the north east. I can't wait to give this a try.
Do you think I should roll it out under the horizontal section, or just try to make a square around the vertical? Because I'm mostly interested in increasing the skywave propagation.
Glad you posted this. I was thinking about buying some more electric fence wire because a few of my ground radials have broken off somehow. Well, now I'm definitely going to try this. I kind of disregarded it in the past because I knew that it would make it a hassle walking around the base of the antenna. I have to do some shrub pruning because my antenna is in a field and a bunch of stuff has grown up around the base. Now I know it's worth it to chop those plants down so I can lay this stuff out. I'll try to find the variety without the plastic.
I've recently been doing a ton of experiments on the AM band. The shunt coil on my antenna has proven to need adjustments to tweak the frequency after rains, so I purchased a roller inductor that I am going to enclose in a weather proof case. If anyone's curious, I needed a 7uH inductor to get a good SWR on top band AM. I am a bit concerned about the contact area of the wheel getting too hot. I may end up needing a heavier-duty one with a wiper instead of wheel for better contact. I've pretty much quit with FM entirely just to be safer, plus AM is a lot more fun and mysterious. In the evenings, you may occasionally hear my signal on 1710 AM in the north east. I can't wait to give this a try.
Do you think I should roll it out under the horizontal section, or just try to make a square around the vertical? Because I'm mostly interested in increasing the skywave propagation.
Roll it out wherever you can. Under the horizontal section is probably best but the idea is to run it from the antenna outward just like spokes of the radial system. It might actually be a better idea to go with the green coated stuff and just scrape off the plastic where you want to connect since that coating will weatherproof it and make it last longer.
I wouldn't spend too much money though, try to ask around and see if you can score some cheaply from someone. The stuff new isn't exactly cheap. Chicken wire of course is far cheaper and will work fine too but is thinner and may not survive many years in rain from rust. Most of this stuff will probably self bury in time, or you can flood the area with water and walk on it a few times to slosh it under the mud, but that's only to make it more visually appealing as laying on top or under dirt will make no difference to RF.
It's kind of funny how AM broadcasting is so hillbilly like when it comes to the aerial system. Some of the goofiest setups made of random junk often performs best. Got to use what you can for that earthing system lol. And yes AM is far more fun and intimidating than FM broadcast band stuff in my opinion. Something about the compromise antenna systems, the weird effects of low frequencies that penetrate buildings and hills much easier, and the challenge! The challenge for me is the most fun part because most people don't expect pirates to be on the AM broadcast band because of the mindset of needing huge antennas and huge lots to fit them in. No one expects an AM pirate to be broadcasting tens of miles day and hundreds at night out of a small house lot or a trailer, and unlike FM it's not monitored as much and leaves a lot of freedom. FM broadcasting is like plug&play mostly, just buy some coax, antenna, and a TX and you're on the air if you have a tall structure, whereas AM actually takes some planning and experimenting for the antenna and nothing is plug&play and good luck finding an AM TX on amazon lol.
Roll it out wherever you can. Under the horizontal section is probably best but the idea is to run it from the antenna outward just like spokes of the radial system. It might actually be a better idea to go with the green coated stuff and just scrape off the plastic where you want to connect since that coating will weatherproof it and make it last longer.
I wouldn't spend too much money though, try to ask around and see if you can score some cheaply from someone. The stuff new isn't exactly cheap. Chicken wire of course is far cheaper and will work fine too but is thinner and may not survive many years in rain from rust. Most of this stuff will probably self bury in time, or you can flood the area with water and walk on it a few times to slosh it under the mud, but that's only to make it more visually appealing as laying on top or under dirt will make no difference to RF.
It's kind of funny how AM broadcasting is so hillbilly like when it comes to the aerial system. Some of the goofiest setups made of random junk often performs best. Got to use what you can for that earthing system lol. And yes AM is far more fun and intimidating than FM broadcast band stuff in my opinion. Something about the compromise antenna systems, the weird effects of low frequencies that penetrate buildings and hills much easier, and the challenge! The challenge for me is the most fun part because most people don't expect pirates to be on the AM broadcast band because of the mindset of needing huge antennas and huge lots to fit them in. No one expects an AM pirate to be broadcasting tens of miles day and hundreds at night out of a small house lot or a trailer, and unlike FM it's not monitored as much and leaves a lot of freedom. FM broadcasting is like plug&play mostly, just buy some coax, antenna, and a TX and you're on the air if you have a tall structure, whereas AM actually takes some planning and experimenting for the antenna and nothing is plug&play and good luck finding an AM TX on amazon lol.
Well, I took the advice and finished installing the ground screen yesterday. It was not easy due to all the shrubs that had grown up around the antenna. I installed ~200 ft of 5 ft wide chicken wire. Most of it is surrounding the base of the antenna, but one leg extends out under the horizontal portion of the antenna. I tested it last night. There is an improvement, but it's not very much via skywave. The local groundwave seems to have improved a lot though. I don't have exact measurements for the groundwave, but for the skywave, the increase was about 5db. So that's about a 3 fold increase, but it didn't seem to make much of a difference in signal quality on the SDRs.
I'm glad I did it, but I don't think I would add more because the gain didn't make too much difference on the skywave which is what I care about most. I'm happy it improved. I don't think I will ever get the range of a real broadcast station and I'm beginning to think most of it is dependent on the poor ground conductivity. I drove past some swamps while listening and even when the signal was terrible before entering, when I was passing the swamp, the signal came back loud and clear. This happened a few times, and it's showing me how much the ground conductivity really matters. I think if I had the same setup in a different part of the country, I would see much better performance. Most of the soil here is filled with boulders.
Roll it out wherever you can. Under the horizontal section is probably best but the idea is to run it from the antenna outward just like spokes of the radial system. It might actually be a better idea to go with the green coated stuff and just scrape off the plastic where you want to connect since that coating will weatherproof it and make it last longer.
I wouldn't spend too much money though, try to ask around and see if you can score some cheaply from someone. The stuff new isn't exactly cheap. Chicken wire of course is far cheaper and will work fine too but is thinner and may not survive many years in rain from rust. Most of this stuff will probably self bury in time, or you can flood the area with water and walk on it a few times to slosh it under the mud, but that's only to make it more visually appealing as laying on top or under dirt will make no difference to RF.
It's kind of funny how AM broadcasting is so hillbilly like when it comes to the aerial system. Some of the goofiest setups made of random junk often performs best. Got to use what you can for that earthing system lol. And yes AM is far more fun and intimidating than FM broadcast band stuff in my opinion. Something about the compromise antenna systems, the weird effects of low frequencies that penetrate buildings and hills much easier, and the challenge! The challenge for me is the most fun part because most people don't expect pirates to be on the AM broadcast band because of the mindset of needing huge antennas and huge lots to fit them in. No one expects an AM pirate to be broadcasting tens of miles day and hundreds at night out of a small house lot or a trailer, and unlike FM it's not monitored as much and leaves a lot of freedom. FM broadcasting is like plug&play mostly, just buy some coax, antenna, and a TX and you're on the air if you have a tall structure, whereas AM actually takes some planning and experimenting for the antenna and nothing is plug&play and good luck finding an AM TX on amazon lol.
Well, I took the advice and finished installing the ground screen yesterday. It was not easy due to all the shrubs that had grown up around the antenna. I installed ~200 ft of 5 ft wide chicken wire. Most of it is surrounding the base of the antenna, but one leg extends out under the horizontal portion of the antenna. I tested it last night. There is an improvement, but it's not very much via skywave. The local groundwave seems to have improved a lot though. I don't have exact measurements for the groundwave, but for the skywave, the increase was about 5db. So that's about a 3 fold increase, but it didn't seem to make much of a difference in signal quality on the SDRs.
I'm glad I did it, but I don't think I would add more because the gain didn't make too much difference on the skywave which is what I care about most. I'm happy it improved. I don't think I will ever get the range of a real broadcast station and I'm beginning to think most of it is dependent on the poor ground conductivity. I drove past some swamps while listening and even when the signal was terrible before entering, when I was passing the swamp, the signal came back loud and clear. This happened a few times, and it's showing me how much the ground conductivity really matters. I think if I had the same setup in a different part of the country, I would see much better performance. Most of the soil here is filled with boulders.
Very good point about ground conductivity. Here I notice my reception off my AM broadcast antenna improves dramatically when it rains, and of course winters here in the midwest show incredible improvement. This shows me that ground radial area of shortened antennas makes the largest impact other than legit height above ground.
Glad to see you saw improvement. It's all those little things that add up eventually. Not sure what the weather or seasons are like where you're at, but if you get winters like here or rain filled spring times you will notice a puny signal become a whopper on AM for both transmit and receive. I mean amateur radio operators have noticed this since the beginning of their use. Copy their info and adjust frequency for pirating and same logic stills sticks.
Either way it's a fun endeavor. Can always run more power when weather or ground conditions suck. Good thing with MW AM broadcast is that RF stages are stupid simple to design if you're used to higher frequency stuff. Long connects? No issue, parasitics? RF beads, Expensive FETs? IRF parts for dollars can get you hundreds of watts on the dollar.
Keep on keeping on, lemme know your progress as you go or if you give up. Not many people pirating MW and yeah it's work, but for the tech types like me that's more than half the fun.
And yeah you're never going to get close to a full 1/4 wave GP antenna the big broadcasters use. None of us will, not ham, not pirate. All antennas at these frequencies are compromise antennas, but when in doubt think about how far these little part 15 broadcasters are getting on MW. They are running 100mw input power and radiating microwatts like part 15 FM using legit full dipoles, but yet their narrow bandwidth covers 1/4 mile or more compared to the same effective radiating power of part 15 legal FM transmitters that get less than a few hundred feet range. That should clue you in on how AM MW holds far more potential than you might give it credit for. As the old saying goes too... you never know who might be listening.
The bit about running tractor fencing under the base of the antenna is very interesting. I'll bet a 1-5 Watt AM signal would do quite well with that sort of layout and could reach 3-4 miles easily. Nice Range for a small town.
I've had difficulty reaching the market in the town I live in which is 1 1/4 miles away. But in the opposite direction I can be heard on a car Radio about 3-4 miles in certain directions. A portable can hear me about 1 mile and maybe 1/3rd. I thought about raising the antenna to see if that would make a difference but never thought about trying the underground screen effect due to what the landlord may think about tearing up the lawn.
I may be able to bury the wire so its not noticeable and get away with it and it may be something to try if its going to increase my AM signal that much more. We will have to check into this too.
The bit about running tractor fencing under the base of the antenna is very interesting. I'll bet a 1-5 Watt AM signal would do quite well with that sort of layout and could reach 3-4 miles easily. Nice Range for a small town.
I've had difficulty reaching the market in the town I live in which is 1 1/4 miles away. But in the opposite direction I can be heard on a car Radio about 3-4 miles in certain directions. A portable can hear me about 1 mile and maybe 1/3rd. I thought about raising the antenna to see if that would make a difference but never thought about trying the underground screen effect due to what the landlord may think about tearing up the lawn.
I may be able to bury the wire so its not noticeable and get away with it and it may be something to try if its going to increase my AM signal that much more. We will have to check into this too.
Yeah, raising the antenna on the AM band is going to have little to no effect. The most important part is a good ground and an as long as possible vertical. If you're doing part 15, then you are limited in that aspect, but as far as I know, the grounding is not limited with part 15?
You don't mention what your current grounding situation is, but if you have something like just a ground rod, then you will see a big improvement with the screen. It's much easier to deal with than individual radials anyway and you can just roll it up to remove it (if it hasn't self buried itself overtime). If you staple it down with lawn staples everywhere, then it should lay flat enough to not be a problem with mowing, but you need to be very careful around the edges where it tends to curl up.
I've covered a 1000 miles with an inverted L and ground screen.
Thanks Kage!
Unfortunately, the inverted L fell down with the first snow and I don't think I can put it up again in the snow. The spiderbeam (it's a telescoping pole) collapsed. I think ice got into the clamps or something.
Part 15 AM broadcasting does have a ground wire rule. Basically any part of the ground system has to be subtracted from the radiating element to be within legal specifications. Part 15 operators who use long pieces of coax from the transmitter to the antenna forget that the shield of the coax can radiate as well as the aerial. When in question if the FCC shows up all it takes is a measurement to find out they are radiating more than allowed. This has happened to a few Part 15 stations now where the engineer thought they were within legal means. Of course the only reason they got caught broadcasting for miles was because they advertised, were on 24/7, ran the station like a licensed outlet, and so on.
Basically the only legal way to do things is to have the antenna connected directly to the transmitter and have the whole unit in a weatherproof box outdoors. It's questionable then if the power going out to the transmitter causes a ground element that radiates. To further reduce radiation on the ground lead I think some transmitters put a choke on the power going in along with modulation inputs.
This leaves a harsh reality to LPAM Part 15 operators.. if your signal is getting out more than 1/4 mile or so you probably have more radiating than just the legal 10' radiating element. I've watched some youtube videos and heard stories of operators getting 2+ miles but don't take into account that long lengths of coax or other connections to the transmitter may be acting as an earth radial extending the overall length of the 10' radiator to an unknown higher length. On the other hand this does go to show how important the ground system is on the pirate side of implementation. If you want a killer signal you need as much ground mesh as you need wire in the sky and since none of us can setup a full 1/4 wave with a full radial system at the base it's all a compromise antenna in the end, but if hams can do it on 160m band, so can we on the top AM broadcast band.
I've covered a 1000 miles with an inverted L and ground screen. Thanks Kage!
Sure I give out advice after the long hours researching and others get the big numbers lol. Furthest reception reports I got were a few cities away, and maybe faint carrier with music a state or two away but I mostly focus on local daytime anyway as night here on 1710kHz is pounded by a local 1700kHz IBOC station. I do only run 25 watts though, but you got big fish coverage, I keep getting reception from minnows. Time to upgrade my TX design eventually I guess when I'm not stuck right next to neighbors. I already knock my own telephone out because of the intense field strength. Small lots suck Guessing you're talking shortwave inv. L usage though?
I've covered a 1000 miles with an inverted L and ground screen. Thanks Kage!
Sure I give out advice after the long hours researching and others get the big numbers lol. Furthest reception reports I got were a few cities away, and maybe faint carrier with music a state or two away but I mostly focus on local daytime anyway as night here on 1710kHz is pounded by a local 1700kHz IBOC station. I do only run 25 watts though, but you got big fish coverage, I keep getting reception from minnows. Time to upgrade my TX design eventually I guess when I'm not stuck right next to neighbors. I already knock my own telephone out because of the intense field strength. Small lots suck Guessing you're talking shortwave inv. L usage though?
I focus on nighttime broadcasting because the signal travels farther and I actually don't care much about good local cause I'm in the middle of nowhere. It keeps me safer because most of my signal is by skywave and my groundwave doesn't meet the skywave so it acts as a wall for the FCC.
Yeah, sometimes my internet stops working when I transmit And it's wired ethernet, not wifi.
No, I am not talking about shortwave. I reached that far on the AM broadcast band.
It sucks that the antenna came down though. I was really looking forward to broadcasting in the winter. I'm gonna call some tree guys to see if they can put a hook in a tree, so I can hang an inverted V. There's no way I can put my L back up in this weather. I wonder how well the inverted V is going to work on the AM band. Will it be better or worse than the L? It will barely fit on my property. It should span almost all the way across. There is a good 60ft tree in the middle, so that's pretty high up. I think it will work pretty well. I hope they don't charge too much. This is really like an addiction to me.
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Guessing you're talking shortwave inv. L usage though?
And it's wired ethernet, not wifi.