EFHW Your Questions Answered about the End Fed Half Wave Dipole
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- Опубликовано: 26 июн 2024
- The End Fed Half Wave (EFHW) is one of the most popular antennas and is currently proving to be one of the best options for new Hams and those that have limitations on what they can install in their gardens or back yards. Peter G3OJV discusses and answers some the most frequently asked questions.
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As ever it is amazing to see a business owner helping us not have to buy things! As a new amateur with a very limited budget I have learned a lot from your videos. Yours and Callum (DX Commander) attitude and friendliness convinced me to take the plunge after being put off in my youth by less than welcoming characters back then (almost 40 years ago!) . Thank you.
Many thanks for your support. I can’t promise not to feature products occasionally, but generally where there is an aspect that I think hams need to know about. Enjoy the hobby. 73 Peter.
The David Attenborough delivery was great!
Excellent video! I use an EFHW cut for 40m and it works quite well. I have had DX contacts from Eastern Canada to Asia, to Australia, to all of Europe and as far south as Antarctica. Record DX using FT8 is 16,900 kms. My only complaint is that it picks up a lot of noise - noise floor is S7 on 40 and S4-5 on 20. Most DX is on 20 - 10 meters. My set up is a home-brew 49:1 mounted on a fence post at two meters, the wire goes up a pole about 17 feet, then across the yard to a paint pole at about 15 feet. PS, I have a pretty good tuner and have also made contacts on 80, 30, 17 and 12 as well. Canada to the Balaeric Islands on 80m using a wire that is half the correct 1/2 wave length ~6,000 kms. Not too bad!
Excellent advice Peter,like you said I personally would rather enjoy operating than worry about not having a text book perfect antenna.
Yes agreed. 73 Peter
I love my EFHF and have really good results from it. Thanks Peter 😁
Many thanks and good to hear from you.
Many thanks Peter, just the info i was looking for
Glad it was of help.
thank you - just the information I was looking for.
Thank you so much for this information. I have been trying to decide on an EFHW Dipole. I currently use an Inverted V resonant at 20 meters. I am going to erect an End Fed Dipole this weekend. I am a new Amateur Operator in the United States. I so enjoy watching your videos. I have learned so much from your instruction. Thank you. 73 from Edward Cheek, KM4MMD
Many thanks Esward.
Another nice video. Very well explained. Thank you.
Hi Mike. Glad it was helpful.
Thanks for this awesome information about the EFHW antenna. Very informative and now I feel more confident in building one.
Yes go for it!
The EFHW is the best antenna for the money in my opinion
Yes, you are not alone there!
well said sir.
Superb info, thank You! 73
You are very welcome.
Great video, Peter, love the relaxed and simple informative approach. I use EFHW for portable use - easy to erect and easy to pack up. 73 !
Great to hear from you. Yes the EFHW has many applications. Have fun,
Very good video, thank you
Thanks for your support
Thank you for an excellent video on the “practical application” of antennas. So often we are besieged with publications claiming only the “perfect antenna in the perfect location” will work. Personally having used aluminum canoes on sawhorses, foil ductwork tape, and expandable bathroom vent hose for antennas, I concur that you can have a lot of fun, and even work DX, with the most humble of antennas. 73 de Dan WD4DB
Many thanks Dan. Yes, if it works use it.
Good stuff
I just got to watch your video . I'm just getting into ham radio . I enjoyed it and would love to see one of center feed antenna
Love your presentation and the flexability and practical nature of teaching........ Try it youll like it!!!!! Ki5CY
Very good Peter My end fed sits on the top of the 6ft fence 80 metres down to the bottom of the garden, works like a dream antenna , your design as well, as does the 49:1 unun your design, bought the wire from you👍👍😊😊,happy days & stealth as well, loving my QRP station, Paul M0BSW
Hi Paul, great to hear from you and sounds like toy are doing well. Keep at it!!
Great advice as always. I recently put an 80 EFHW in my attic. I had to wrap it around 3 times. Not pretty. But, it does work a bit better than the G5RV jr it replaced. Then I added just enough LMR 400 coax. Small changes have significantly increased performance. The first voice contact I had on the new antenna was in England of all places. I was shocked.
well done. Keep at it.
Excellent discussion Peter. I found that the 110 micro Henry coil caused a very narrow bandwidth on 80 meter. So I have cut the additional wire after the coil for exactly the frequency where I usually work. Thanks for the information. Always interesting.
Hi Danie, yes you will get a narrow bandwidth because on 80m the antenna is very short compared to a full size half wave. 73 Peter
EFHW is great. Mine's fed at guttering height on the house wall and goes down the graden to a tree, only about 5m above ground for most of it's run and I got DXCC on it with only 50 watts. I also recommended it to an M7 friend who had to dog-leg his and drop the end to make it fit his small garden and he's doing well with it too. It's easy to make, simple to install and unobtrusive, ideal for suburbia
Thanks Alan. Great to hear about your setup.
100% endorse your key points Pete. I was advised to put the un-un at gutter level, run the wire down the garden and then bring any excess back at an angle. Works a treat and allows me to work stations on 40m I cannot hear on other antennas. I did find I needed a choke 'balun' at the transmitter end of the feeder to prevent common mode currents messing up my CAT connection. Also cleaned up the VNA plot.
Yes that line isolator at the tx end is important.
I have only just put up a a random wire which I guess I could call a EFHW. 135FT of wire averaging about six feet high and hanging on branches and it is the three sides of a rectangle as it goes around my garden. I used a very cheap 1:49 unun without a counterpoise and fed it straight into my IC 705 without an ATU. The SWR was passable on most bands. My first contacts on 20m running 5 watts were with Quebec and Ontario. This is 1400:km. Tnx for a great and reassuring video.
Hi Michael. That is great news. Keep at it.
I have never bothered with the small coil on my 66' EFHW 40-10m antenna. However I have and am using a coil at the far end of the wire for covering the low end of the 80m band. I run my EFHW as a sloper from 10 feet to 50 feet at the far end. I bend the last 10 feet of the 66 feet down to the the vertical making the 80m coil and the 3-4 feet of wire after the coil in the vertical. I do ground the transformer with a piece of wire and a 6 foot ground rod. My antenna is home brewed for high RF power. I used 14 gauge wire to wined my 3 stacked 43 mix cores. Thanks Peter for the great videos. 73 Joe
Hi Joseph, sounds a good setup. Nice to hear from you.
"Amateurs not professional" well said. Very good video. Thank you .73.
Thanks Andy
I have one with an 80-meter coil. works a treat.
Thanks Brian.
Hello Peter, very interesting topic, I think I’m correct in saying that the coax screen acts as a form of counterpoise for the Antenna, having experimented with my EFHW, adding an additional wire to the 49/1 makes no difference.73
Hi Alan, the EFHW only requires a tiny amount of counterpoise and I have often used just a 2m length of coax.
My setup. 20 feet of coax to a 5 ferrite choke pigtail. No grounds or counterpoise. No ground at radio either. Antenna is a My Antenna 40-10. I break pile ups with 100 watts and work the world. It is also in a very sharp inverted vee. Strange but it works great.
Hi Larry. great to get your report.
A very timely video. I have just moved into a new house with a garden just shy of 20m long and was wondering if I'd get away with a bit of a bendy wire..
Hi Steve. 20m wire down the garden, add an 80m choke coil and drop the last few feet vertical. 80m - 10m 5-Bands. 73 Peter
I also found that feeding the 49/1 down the garden works better for me with less noise and the SWR is very good.
Interesting. 73 Peter
Well said, Peter.
Great video. One minor thing I take exception to is the radiation pattern on the second harmonic. For example, using an 80m EFHW on 40 meters your radiation pattern is vastly different than what the same antenna yields from a center fed version. The current maxima on 40m will be out of phase and the overhead, high angle lobe will cancel leaving you with a deep null at 90 degrees. This may or may not be an issue. It's a real big issue for a 160m EFHW being used on 80m however. In fact, on 80m your regional coverage will be at least 10dB down from the same antenna fed in the center. For this reason I consider the 160 EFHW a one band antenna. The higher harmonics end up being too high in frequency anyway and the transformer ratio requirements are also different.
The radiation pattern is virtually the same whether you feed a resonant length at the centre or at the end. The harmonics follow the same pattern. This is covered in several issues of ARRL Antenna Handbook. The harmonic resonant drift can be dealt with by the small correction coil often placed near the feeder end of the antenna.
You can use small wire like #18 stranded as it does not need to support the coax and the shorter coax run makes up for any transformer losses. One could also add remote controlled relays at the transformer to switch to different radiators like a half wave vertical for 10M, even 20 a run of CAT5 will work.
Yes a relay option would work. Best some form of latching relay.
Thanks for these great interesting videos I love watching them and learning more.
Have you ever done a video on problems with microphones at all ?
Myself and others I know have experienced problems with changing out the stock microphones to say a desk microphone etc and have had problems with what I think must be rf. I’ve had the vfo changing frequency and sometimes noises or interference with my external speaker and on the transmit audio.
Just a thought and apologies if there is a video you have done already and I’ve missed it.
Many thanks.
OK Dean, I will put that on the list.
@@watersstanton many thanks much appreciated.
Thanks for all your videos. I wonder if you can compare 49:1 vs 64:1 in the future. Any difference?
I could not find any obvious advantage so stick with 49:1
Excellent video! One question not covered, which I hear/see often with conflicting answers. Is a common mode choke needed on the feed line?
Not absolutely needed, but I always add one at tx end in order to get accurate VSWR readings.
I add my common mode choke 0.05 wavelengths down from the feed point by wrapping the coax on an FT240-31 toroid core (I just use RG-58 coax and wind 10 turns on the core). The reason I place it at the 0.05 wavelength location is for several reasons. One reason is that the 0.05 wavelength location (on the lowest band of operation) provides the amount of required counterpoise that was mentioned in the video, the second reason is that it isolates the rest of the coax (really the coax shield) from altering the resonate frequency and therefore the SWR when handling the coax below the choke (easily observed when watching SWR on a VNA or SWR meter), and the 3rd reason is that it prevents common mode noise induced on the long run of coax below the choke from reaching the feedpoint (noise generated from within the shack and/or house as an example) and this helps reduce receive noise. Just FYI, Don (wd8dsb)
Excellent video Peter, gets all the relevant points across in less than 20mins. I'm fortunate that at my QTH I have space for a full size 40/80 dipole and a separate set up for 20m and above, but I use an EFHW with a 110uH coil for /P. One thing I can't do at home is get on top band - are you aware of anyone using a full size 80m EFHW with a coil + "tail" set up (similar to the way to add 80m to a 40m EFHW) to get on top band, or would there be easier solutions (e.g. to make a base loaded vertical). Thanks
I have no doubt it would work although I have not tried it. But two issues may need noting. Does the UnUn you use, cover 160m? Also, the band coverage will be restricted, maybe as small as 50kHz.
As Peter already stated, the bandwidth will be very small this way. You may try to use the wire of your 80-halfwave (you have to disconnect it from the unun!!!) as a quarterwave radiator against some (buried) radials and any bigger metal structure in your environment. If you find this solution working, you may build a remote solution that allows you to switch between using the wire endfed or as a "vertical" quarterwave on 160. There are only few publications on the web describing this solution, but I'm sure you will find some of them. Besides the advantage of a (slightly) wider bandwidth, you don't need to care whether your unun core covers 160 or not. (Plus you are most probably able to run 160 with full legal power - no matter which country your QTH is...)
73!
DL1WTE
High voltage at the unun is an issue, yes? Does that mean the unun should placed high off the ground?
great peter n4jrs 73
Many thanks.
Nice 1 Peter I have found not to cut the wire shorter I do a Z +/- 1m from transformer +/- 4-8 " ( 100-200mm) long tape/zip/cable tie together and it give me some adjustment to tune as I found it does change from place to place and donot have to take down to adjust it just slide the Z longer or shorter,
Thank you,
Pieter,
ZL1PDT ex ZS1PDT
Hi Pieter, that’s an interesting approach. Many thanks.
Question: An EFHW is set up as a sloper, oriented North/South, with the high point at the North, wire sloping downward toward the South and the coax feed point at the South a few feet above ground. Radiation will be broadside to the wire. Does the fact that the wire slopes down from North to South mean the antenna will also tend to have stronger radiation in the direction of the slope, South in this scenario?
Hello Peter, I hope you'll answer this question, I live in a community where I cannot erect an antenna, so my only option is an EFHW running parallel to the aluminum gutter around the house. I plan to use aluminum Christmas light clips to attach an insulated wire, (known in North America as telephone station or Z wire, four insulated 22awg conductors in a PVC jacket). What effect do you think will the proximity of the gutter have on the antenna?
Thanks Peter. Very useful. If I ever get on the air I think it will almost certainly be an EFHW. May end up as an inverted V and also bent horizontally but it sounds like you can do almost anything with this antenna and it does not grumble too much. Thanks again. Stu. M7EOS
Thanks Stu.
I have two EFHW antennas. One I built with a homemade 49:1 Unun and the other was made using an Unun purchased on Amazon. Both of them are tuned for 40 meters through 10 meters. I installed them in a upward slope from a few feet above ground to a tree about 20 feet high.
My problem is my G90 Radio waterfall shows an evenly spaced series of noise bands on all bands. Noise is quite loud and the noise bands are fairly wide.
What would you recommend to eliminate this noise? Using a vertical whip in same location, I do not get this noise.
Peter a couple of years ago you mentioned using a line isolator or 1:1 balun in the feeder, close to the transceiver but after any meter. Would you still recommend this? I'm building an 80M EFHW.
Yes.
Peter, what is the diverence between a half wave antenna and a dipole antenna? 3Db? ;)
A half Wave antenna (EFHW)) is almost identical to a dipole of the same length. Zero gain advantage.
One further question Pete, Does using a ground with an EFHW reduce noise? I'm sceptical myself, but wonder if you've done any tests yourself 73
Probably not if you fit a line isolator at the tx end.
Peter, I have been thinking about the LDG 49-1 unun for portable use with an end fed. It has two screw terminals, one is obviously for the antenna but the other is marked earth. Do I need to make a ground spike to use as earth or will it be fine without for portable use? Thanks
I have never found any benefit, so I leave it unconnected..
@@watersstanton thanks Peter, 73’s
A VERTICAL EFHW will give you a lot of DX! It has a good take off angle for DX.
How low can you go? I tested an EFHW lying in dry grass in open plains. It made over 600 km on 20m SSB.
Thanks Ron.
Would there be any reason why I couldn’t run an end fed antenna in my attic running the antenna down to the main floor making an inverted L shape? The antenna would run through the floors to come out just by my rig and connect to a 9:1 unun? Just one little hole for the antenna going through the floor. Just a thought.
Yes you can. But you would need to add a short counterpoise of 3 or 4 metres - could lay on the floor - in order to keep rf voltage off the radio.
@@watersstanton Thank you for your kind reply! I appreciate it! 73 Curtis KD9ZDH
The old saying and group 100 watts and a wire is applicable. Just GOTA(Get On The Air) and make contacts. 📻🎧
Agreed
Thanks for another great video Peter ,
Do you recommend a RF chcke / ugly balun near the 49/1 balun on the feed line or behind radio in the radio shack ?
The plastic coating on my EFHW wire is perished right along the full length and cracks are forming due the the hot Australian sun shine
water gets in does this matter from what I have observed
it doesn't seem to be making a difference when it rains but I'm really not sure
I don't have much test equipment like antenna analyzer only a VSWR meter
so I'm not sure if the impedance is changing or any other strange effects when it gets damp, The balun is water tight.
I would appreciate your option. thanks in advance Peter 73
Hi there. Put the choke near the transmitter end of the cable. Water in the antenna wire should have no affect. After all we sometimes use bare wire anyway, and that gets wet! 73 Peter.
@@watersstanton Thank you very much 73
If I cut an EFHW for 20m is the second harmonic only 10m? Second is how many wraps to bring 10m into better resonance.
Second harmonic is 10m. The number of wraps depends on the wire and and the plastic covering. Try 2ft tightly wrapped and then trim back as needed.
inverted “L” or sloper
Well, I turned my EFHW into an inverted V, I messed up, but it turned out well. I used SS guy wires which apparently radiate instead of rope or fiber. So I had an NVIS that worked on multiple bands. Now I have accidentally created the PERFECT 20M antenna. Get 2,000 miles with 20 over 9. I have other antennas for 70cm, 2M, 6M, and 10 M. I suppose I could hook up my unused LDG 200 tuner to try to bring 40M back.
Thanks for sharing Steve
Hi Steve, what length wire did you use for that inverted v with the great results on 20 meters,. I have been wanting to try that.
@@briantrask8173 66ft for the primary radiator, about 10 ft off ground at each end, 2.5 lb weight at end opposite house to keep it taught. Wanted to go 33 feet in the center but couldn't get the mast up by myself, so went 26 feet in center. I have lots of diagrams and pictures.
Great Video. Thanks. Title should probably say "End Fed Half Wave Antenna." It's not a dipole. -- kc4i