My wifee was head of home insurance for 21 states and I asked if she was aware of any fire or damage claim denied due to illegal wiring or not meeting code. None was the answer.
End fed random wire
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AC9KH
Member
I've used both random EFW and EFHW and they work every bit as good as a dipole. My current go-to antenna is a 130ft EFW vertical, with a switch to switch out the transformer primary, which converts it to a 1/4 wave vertical on 160. It will hit dx stations on both 80 and 160 meters that the dipole can't reach. Dipoles are great for heating dirt and making worms uncomfortable but most people can't get 'em high enough on either 80 or 160 to get a decent radiation takeoff angle and they end up being nothing but a NVIS antenna with high ground losses. A EFW only needs one support while a dipole needs two, plus the weight of the feedline hanging off the center of it.
As far as wire? Virtually anything works, including rusty barbed fence wire stetched between a couple corner post insulators, just shine it up a bit where you hook the feedline to it. The key to making a EFW work is the RF ground. If your soil type doesn't conduct RF very well, lay out some counterpoise wires from your ground rod.
W4AXW
A keeper of the SSB flame
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No doubt she's correct, but it would suck to be the first.
K6GBW
Member
Dipoles don’t “heat the dirt” any more than any other antenna that’s low to the ground. They do not require two supports (mine is held up in the center right now) and dipoles don’t use torrid made transformers that heat up and bleed off power. There is no argument at all that dipoles are more efficient. Most end feds also need a tuner and that’s more loss. While I’m sure you are satisfied with an end fed antenna the science can’t be disputed, you get more juice into the air with a properly tuned dipole.
W4AXW
A keeper of the SSB flame
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Well said.............
AC9KH
Member
In theory there is no difference between theory and practice. In practice there is. You're also going to try to claim a dipole is "scientifically better" than a vertical? Your transmitter likely has a unbalanced 50 ohm output. Your dipole is a balanced load and does not have 50 ohm impedance at the feedpoint - it is 73. You can't build the "ideal" dipole in free space so you're going to have ground losses. And you're still going to need a transformer to convert from unbalanced output to a balanced load. And it's going to require a very long feedline to get one at any decent height for 80 or 160 meters.
My EFW, OTOH, can be fed with a 6' feeder. Even if you use a parallel feeder with a balun in your tuner to feed a dipole, my transmission line losses are lower than yours. With a properly wound impedance matching transformer and the wire cut for resonance on the desired band of operation, my load is a perfect 50 ohm unbalanced, which matches my transmitter. Instead of wasting wire length to get to the feedpoint of a properly installed dipole, that's all radiating element with my EFW. My total antenna system losses are no greater, or no less than yours. Guaranteed.
Don't throw out "science" when in practice you can't build an "ideal" dipole in free space. The EFW is no more of a "compromise antenna" than your dipole is, unless you purposely or inadvertently design it to be.
K6GBW
Member
Jesus dude, are you one of those people that takes it as a personal insult if someone disagrees with you? I've been working with radio for over fifty years and my personal experience is that end feds using a transformer are not as efficient as center fed dipoles. You disagree...fantastic. End feed to your hearts content but if you stick a toroid transformer into the mix you are losing power that could otherwise go into the air. So you do you and I'll do me.
AC9KH
Member
I'm not taking anything personal. it would appear to be the other way around. I'm pointing out inaccuracies in your generalizations.
You are welcome to try this experiment for yourself:
Grab your handy field strength meter and test the field strength of your dipole.
Now, take the balun and feedline off it and short the two elements together.
End feed it with a transformer that will match the impedance to your transmitter, fed against a 8ft ground rod.
If your soil type doesn't conduct RF well, lay out a single counterpoise wire from the ground rod - the length don't really matter.
Measure the field strength of this new EFHW.
You will find there is zero difference. You will also find that the radiation pattern is identical. If you don't have time to drive around and model it with your field strength meter, model it with EZNEC if you want. There is zero difference.
Now, shorten your feedline to only what is required to reach the feedpoint of the EFHW. Let me know how many V/m you pick up in field strength by shortening the feedline. Same identical antenna, same height above ground, same location, just configured two different ways.
If you've been working with radio for 50 years and don't know this yet, it's never too late to learn.
The key is that an antenna is never just an antenna. It is an antenna system that consists of antenna, feedline and impedance matching system.
A dipole in "free space" is about 73 ohms but we don't live or operate in space. The typical HF ham installation has the dipole at heights above ground where the impedance is lower than 50 ohms due to ground effects. If the dipole is at exact 1/2 wave increments above ground then it will usually be higher than 50 ohms but you would need to be many wavelengths high before your going to reach even 70 ohms.
EZNEC should show about the same gain and radiation pattern for a resonant dipole and an EFHW cut for the same lowest frequency. The EFHW will have a slight amount of loss due to the transformer, probably well under 1dB and the radiation pattern will be skewed a little due to the transformer and feedline coming off one side. Otherwise I don't think most hams can measure the difference between a resonant dipole and an EFHW cut for the same frequency.
EZNEC should show about the same gain and radiation pattern for a resonant dipole and an EFHW cut for the same lowest frequency. The EFHW will have a slight amount of loss due to the transformer, probably well under 1dB and the radiation pattern will be skewed a little due to the transformer and feedline coming off one side. Otherwise I don't think most hams can measure the difference between a resonant dipole and an EFHW cut for the same frequency.
RFI-EMI-GUY
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Great, now I have to worry about ARRL inspectors..
AC9KH
Member
And it does. They are identical. The transformer loss with a 1:7 turn ratio (49:1 impedance), wound on high quality cores, is negligible. About the same as a balun on a dipole, which is also a transformer. Even if you use a so-called "ugly balun" (which is really a choke), the losses are about the same.
The advantage with the EFW is that if you can get the feedpoint relatively close to the radio you will have less transmission line losses to the feedpoint of the antenna than with a dipole cut for the same fundamental, especially on lower bands like 75/80 meters. Significant changes in feedline length are measurable with a decent field strength meter. With good quality RG-8 with 100 watts in on a 100ft length you are going to get about 85 watts out on 20 meters and around 92 watts out on 75 meters - the 49:1 transformer (unun) with a short 6ft feedline holds a significant advantage on 20 meters, and is about a wash on 75 meters.
Of course, many folks will use parallel feeder to a dipole to mitigate the losses with coaxial cable. But you still have to use a transformer to match impedance going from a BALanced load to an UNbalanced output on your radio.
There is no free lunch.
AC9KH
Member
Some possibilities of things you do with a end-fed.
A random length has an advantage of being easily tuneable on multiple bands with lower feedpoint impedance than a EFHW.
The EFHW does not require a ground plane - it is an electrically complete antenna that simply switches polarity on every cycle. However, you can turn the 80m EFHW into a 1/4 wave on 160 if you add a decent groundplane or counterpoise for it.
My transformer has a switch on it that switches out the primary winding and switches in a shunt. This converts the impedance to a resonant 1/4 wave vertical on 160m and use of the tuner is not required on 160 below 1900 kHz.
So with an end-fed you can shorten your wire to a 1/4 wavelength on the fundamental frequency and feed it against earth ground (with a counterpoise wire if necessary), paying attention to that RF ground which is the other half of your antenna. Soil will work if your soil type has good RF conductivity. If your RF ground is less than perfect lay out a counterpoise wire to get the desired impedance after you cut your wire to resonance using your antenna analyzer to determine the VF in the wire.
A wire that's resonant on the fundamental will have a near ideal radiation pattern as compared to a random length. I achieved two fundamental frequencies with the addition of a simple switch.
You'll probably notice that I have a custom-wound transformer. There's a reason for that. If you buy the store-bought stuff for a half-wave you're likely going to get the "standard" 49:1, 2 turn primary, 14 turn secondary with a bifilar on the primary. I didn't want that because I wanted a DC-grounded 1/4 wave vertical for 160 that will handle full legal power, and I needed the extra inductance in the secondary winding to ground to achieve that.
Many times it requires a custom-wound transformer, either altering the number of turns and/or the turn ratio to get the desired result. An antenna analyzer will be an invaluable tool for building an end-fed so you know what you got. If you buy the store-bought 49:1 for an EFHW you may find you need one wound with a 3 turn primary, 20 turn secondary to get a match. Or maybe a 2 turn primary, 15 turn secondary. The impedance change is the square of the turn ratio, winding your own you can build exactly what you need. If you just buy a 49:1 for EFHW or 9:1 for random, that may or may not work depending on the orientation of your wire, how high above ground is it, etc.. These things change the feedpoint impedance.
Keep this in mind because it works with other combinations like an EFHW for 20 meters becoming a 1/4 wave Marconi on 40 meters, but a "standard" 49:1 transformer won't work for that - you'll need a custom wound transformer.
I ran a test last night between my EFW and dipole on 80 meters @ 3.5 watt input to the antennas using JS8Call from Wisconsin to a station in Maryland.
My EFW is a vertical configuration, fed with a 6ft piece of RG-6 TV coax to the transformer consisting of a 3-turn primary, 21-turn secondary wound on twin FT240-43 cores. The wire is 127ft (due to VF) stretched from just outside the shack to the top of my tower at ~70° angle. It is cut for resonance @ 3600kHz, no tuner required.
The dipole is about 70ft above ground. It is stretched from the yardarm at 90 ft above ground on my tower to a pine tree about 70 ft above ground. It is oriented north-south. However it sags in the middle due to the weight of the feeder. It is cut for resonance on 3600kHz, fed with 165 ft of 200 ohm parallel feeder. The feeder is powered from the tuner's balanced output with the use of a 4:1 balun transformer in the tuner. This antenna can be tuned for 160m, but it don't work very well on 160.
I transmitted two SNR? requests to the station in Maryland, one with each antenna. This is the results.
Only a 1/2 s-unit difference. The EFW always comes out on top for DX due to being vertically polarized and a lower radiation takeoff angle as compared to the dipole. However, on NVIS it is the other way around due to the radiation takeoff angle from the vertical being too low on the horizon to be a good NVIS antenna. With horizontal polarization on the EFW there would likely be no difference with the above test.
Go to 160 meters and the EFW will talk to Russia. The dipole will barely make it out of the state because it's electrically too short. Same thing will happen with your random wire. Will it tune on 160? Yes. Will it work on 160? Not very well except on NVIS and your ground losses are very high.
So the point is, consider some different configurations. It sounds like you have the room for it. I tend to lean towards a resonant antenna on the fundamental frequency and put up another antenna for your higher frequencies. On the higher frequencies they get pretty short and are easy to put up. But 75/80 and 160 are very unforgiving of shortened or loaded antennas.
For fifty years, you have been mistaken. An EFHW antenna with a .05 wavelength counterpoise has an efficiency of 97 to 98%, which is the same as that of a dipole.
K6GBW
Member
I'm not trying to tell you what to do. If you like end feds then more power to you (no pun intended). But my experience hasn't shown that to be the case. To each their own.
Compare dipole to EFW, you cant. They are different antenna systems with different properties.
You can compare performance as AC9KH shows. with both antennas properly tuned and matched, I doubt amateur equipment can see a difference.
RANDOM wire is a length that is not reasonant on ham frequencies, but 1/4, 1/2, amd full wave on certain frequencies.
These do require a tuner to match whatever frequency is chosen.
Here is a nice length chart for random wire:
I origonally had 144 foot random wire, then lost near 30 foot in a storm, The difference with now 88 foot is I lost a lot of 160 meters and 80 meters just does tune, higher frequencies work very well even at 54 MHz. Near 7 MHZ is close reasonance.
Sweeping, the SWR is like a roller coaster and 2 Db loss through the tuner.
You can compare performance as AC9KH shows. with both antennas properly tuned and matched, I doubt amateur equipment can see a difference.
RANDOM wire is a length that is not reasonant on ham frequencies, but 1/4, 1/2, amd full wave on certain frequencies.
These do require a tuner to match whatever frequency is chosen.
Here is a nice length chart for random wire:
I origonally had 144 foot random wire, then lost near 30 foot in a storm, The difference with now 88 foot is I lost a lot of 160 meters and 80 meters just does tune, higher frequencies work very well even at 54 MHz. Near 7 MHZ is close reasonance.
Sweeping, the SWR is like a roller coaster and 2 Db loss through the tuner.
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AC9KH
Member
Unfortunately, 160 is a tough one with any sort of shortened antenna. Years ago I had a 260ft dipole but in this part of the country it gets ice on it in the winter and then it breaks. So I went to 10 AWG magnet wire, which has a higher tensile strength, but makes for a very expensive dipole. At 90 ft with with the weight of the feeder hanging on it even the 10 AWG magnet wire breaks after awhile. And that dipole was only good for the Midwest anyway, only on rare occasions would it make it out any further than that.
So I gave up on that. If you want to play with the big boys on 160 you need a vertical. So I loaded up my 120ft tower. I think that would've worked except for the fact that tower has a 16ft diameter wind turbine on it which caused all sorts of electrical problems.
So then I got the idea to build a vertical wire Marconi but the tower wasn't quite tall enough to get resonance so I stretched the wire at a 70° angle to get the wire length I needed. Still using 10 AWG magnet wire. But that worked because it's electrically isolated from the tower and finally I could make it across the pond on 160. But that's slightly directional because of the proximity of the tower.
It wasn't until several years later that I put an impedance matching transformer on that wire to use it on 80.
That 80m resonant wire is usable on 60, 40 and 30m. It will tune on 20, 17, 15, and 12. But it won't tune on 10m. And it don't work worth a darn on anything higher than 30m. And neither does my 130 ft dipole work very well on anything higher than 30m.
I've got another tower mounted vertical that I use for 10, 12, 15, 17, 20 and (most of the time) 30). I've ran many SNR tests to both coasts and into Canada with the dipole vs the short vertical on 30m and the short vertical wins every time.
I've had it in the back of my mind to buy a bunch of aluminum tube and build the vaunted 43ft vertical for those mid-range bands. But I haven't gotten around to that yet. The commercial 43ft designs use a 4:1 balun, which is something I would NOT do unless feeding it with parallel feeder. And, again, even though the 43ft vertical is claimed to work on 160, according to my modeling it would have about -8dBi gain on that band - very lossy compared to the full-length Marconi.
I used a 43ft vertical for awhile and when I tossed the 4:1 balun and put an auto tuner right at the antenna it came alive. I could talk to just about anyone I could hear on 160 using 100w. I had 32 radials about 30ft long each. It also worked great on 80 through 20 and ok on 17, but higher bands not so good. It usually out performed a ZS6BKW at 25ft at the same location on 80 through 20 and the ZS6BKW could not hear most of the people on 160 that blasted in on the 43ft.
Great.... I was wondering about the 43 foot vertical performance with all of these comparisons.
Thanks
Joel
AC9KH
Member
This is what everybody who has run one claims. The 4:1 balun is not such a good idea. And the antenna tends to work better than it should on 80 and 160. According to my model it has about a 25° takeoff angle on 160 and sometimes that's more important than total radiated power on that band.
I just transmitted a single WSPR transmission on 160 at 1/2 watt into the EFW to check prop and this is what I got. This is also a good way to test how well your antenna works on 160m. Unfortunately, there's not a lot of stations in the U.S. that have good 160 capability. It's kind of a small club.
How long is your end fed wire antenna?
I have an active imagination and I can easily see an enthusiast using a bunch of beverages to good effect with 1/2 watt.
Thanks
Joel
