Smarter Than Your Average End Fed Half Wave Antenna
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- เผยแพร่เมื่อ 2 ต.ค. 2022
- In this video I discuss a variation on the #EFHW antenna and can we get it to work slightly differently?
Here the link to both sizes of the reels -
www.fishingmegastore.com/fly-... - วิทยาศาสตร์และเทคโนโลยี
For Field Day, we use a 40 meter EFHW in a 20 meter half square configuration. We found that keeping the feed point 3 feet off the ground and it would easily resonate on 20 with the 49:1 unun. We can consistently work 800+ contacts on 20 only with this antenna.
Fantastic info, thanks. This is the feedback I'm looking for.
looking VERY interesting Colin! I'll be watching this project closely. good luck with the testing! 73, Tom.
Thank you Tom. Not forgetting about your cores. I've tried the 3 stack and to try the 2 stack. I'm thinking if this project works about trying some of the 290 size cores for high power.
Colin, very interested in you experimental results. Thanks for taking the time to share your thoughts. Very cool. 73 W6MGV
Love this idea Colin
Kudos Tim. You had thought of if before me.
Hi Colin .Loving my adjustiwave it’s great! This would a great addition and think it’s a great idea to have the wire on a spool keep going will be first in the queue to have one !!
Thanks Jon, unfortunately this is just a personal project, i just dont have time, i spent so much development adjustiwave it was good to coverost of the R&D.I can forward links to parts If need be
Once you go to the lower band, ie 40m to 80m you have a 1/4wl antenna and you should have a close to 50 Ohm match. Steve Ellington setup his 80m-10m EFHW with a remote switch to direct feed the antenna bypassing the 49:1 autotransformer. He however configured his antennas as an inverted-L.
Yes! Resonance first. Then impedance. Can’t wait.
I have a half square antenna that goes up 4 meters on the flat roof behind the house and then 12 meters horizontally and then 4 meters down again. The height of the flat roof is 3 meters and the start of the antenna is 4 meters high. This works much better than the 12m vertical EFHW I had before. SWR is good on all bands. Even tunes up to 80 meters with the internal tuner of my Yaesu FTDX10. The noise is usually S3 or less on the 40 and 20m band, After testing with someone in the north of the country I went from S5 to S9+. I personally think that 5m-10m-5m is not necessary. so if your garden is smaller, you can also go a little more vertical. I will keep following your videos, and you have a thumbs up from me. (PD0MVP)
Thanks for sharing your experience. Looking forward to getting my one up.
100ft metal tape measures work great for portable operation. Some of them it's possible to build the 49-1 inside the spool especially qrp operating. Cheers from old George
Good shout 👏
I'm making mine out of a all plastic chalk line used in construction ! It's 150 foot one where I removed the chalk line and refilled it with 18ga. Wire . Got it on Amazon $26.00
I've seen others with the chalk line thing, great idea. Make sure the wire is bare like it is here or keep your transformer at the other end of the wire.
Interesting video. I have some experience with half squares on 160, 80, 40 and 20. I find that the 20 meter half square with the top wire at 20 feet is not better than a 20 meter dipole at the same height. However the 40 meter half square is about the same as a 40 meter dipole at the same height. On 80, the half square is far far superior to a dipole at the same height (65 feet) and I could always beat out dipoles near 100 feet by at least one or 2 S-units! In 160 I could not get high enough for the vertical wires so I had to bend them parallel to the ground. It was still a good DX antenna on 160 but takes a lot of room and wire!
I also think that the 20 meter half square has more gain on 15 and 10 meters than it does on 20. It has a clover leaf pattern on 10. On 15 it’s not symmetrical at all but has gain. Again a dipole for 20, 15, or 10 has a lot more gain for the same height above ground. I will add that over sea water the half square will compete with the dipole in the gain department otherwise the dipole always wins. Lots of times for portable work convenience is more important than a couple S-units of gain so if it’s easier to put up than a dipole it’s going to work pretty good.
Really appreciate the real life experience feedback. 40m is my primary band as I have the Hexbeam for 20m - 10m. I need to try the half square in the autumn.
I have done half-squares on 20 with my usual transformer and a couple of 12m poles, and it certainly matches up OK. What I couldn't verify in the field was what the directivity/gain of it actually was. I didn't feel like I was getting any kind of nulls on the shorter skip (eg Europe) even though they should have existed with the way the antenna was set up. Vertical polarisation so definitely of interest by the sea. You have come up with a very interesting way of implementing it !
Thanks for your insights Stu. Thats always the issue and then you start to not believe things. You really need a reference antenna to compare with. Going to try phasing 2 x 20m EFHW's. That's got good potential as the its great to block out 1 direction.
Hi Colin, well an interesting idea for sure, bit too many parts for my liking.
I simply have a 40m vertical antenna with a 7.1meg trap at the top with a extra piece of wire going out and this gives me resonance on 80m and 40m, no transformers or coils, just one pole.most other bands are easy to get even if I have to use my tuner sometimes.
Also on the main I get all round radiation, not just two directions you will achieve.
Your design is a great idea and I will be be interested to see the dx results. But if results are not beyond eu, I personally wouldn't bother, but thats only me and what do I know hi.
Good luck..
I see what your saying Brian. I just love the experimenting and development work. Yes lot of parts but pretty reliable based on my experience. If I can get this over saltwater especially somehow it would be great to see how it performs.
Hi Colin, I am currently working through the same ideas. I done models and they look very good. I cut wire and prepared supports. If weather is OK at the weekend I will do some WSPR tests and compare them to vertical EFHW for 20m band and horizontal 8010. If these come through OK I will use this antenna for CQWW at the end of the month.
Great. Please feedback your info. The more opinions the better.
@@MM0OPXFieldRadio Colin I made simulation using MMANA-GAL software and compered EFHW as HalfSquare with inv-L EFHW4010 (20mtr wire). On paper inv-L has better performance as long as vertical section is at least 6mtr long and rest is horizontal. I mean the gain is higher or equal at the same take off angle. I think that EFHW as HalfSquare would be great for portable ops where higher support might be an issue. At base QTH 7-8mtr up and then horizontal or slightly slopping will be much better. Of course if your vertical part can go as far as 10mtr this would be much much better option for small space. Anyway these are my oservations. I have inv-L with 7mtr vetical part and rest is slightly slopping at present. Performance (RX) is comparable to vertical EFHW2010. Also I found that 15m band is poor from HalfSquare and 10m is excellent. Let us know how you are doing with this project.
GL 73 Marek
Interested in the core you are using. Thanks for taking the time and sharing.
Looks like a 2643251002, Fair-Rite.
@@Aimsport-video Thanks! Not tried these yet.
very interesting and clever. :}
Are drawing the waves for each band to see where there may be cancellation?
You could possibly use some sort of clutch or use a stepper motor to drive the reels. With a Stepper motor it will 'lock' after every set of pulses - so much less chance of things unspooling.
I'll have a bit of a think about this over the next week or so.
My lovely Wife is an automation expert (MSc, BSc, Cyber Security) so I'll pose the problem to her and see what she suggests.
Keep experimenting!
73
Bruce G4ABX
Interesting concept Colin! Didn’t Tim G5TM do a video on a similar concept? Except for the winders. I’ve tried the same with a 20m wire EFHW, and it seemed like I got some gain. Looking forward to seeing your results!
I just remembered that Morten. I will link Tim's video in the description. Hopefully it works.
Great video Collin. What type of core did you wind there?. Do you have the numbers for ordering?
This one here. The picture is wrong on mouser but its the right part number. th-cam.com/video/Xe0wvbOQeok/w-d-xo.html
Very interesting information, thank you. Question: Don't you need to make a crossover while wiring the coil around the toroid? Is it more efficient without the crossover? Thanks
On this core it makes little or no difference. Use the crossover or not to suit component placement.
@@MM0OPXFieldRadio Great, many thanks Mr! Keep up the good work
Hi Colin.
I have tried the Half square for 20m fed with your efhw 64:1 and it works well on 40M and of course 20M. (Fed from the base of one of the vertical sections.) I did use a 5m counterpoise to tame the common mode.
Mine wasn't very high. I used 2off 8M poles.
I think I was able to get some 'gain' on 20M but it wasn't much and honestly probably wasn't worth the effort of taking 2 masts when out portable.
For home however, it would be more interesting -- and your idea of the wind/unwind antenna wires is good -- if this could be automated.
My home shack is about 50 metres from my antenna and it would be a pain needing to go outside every time I wanted to change band selection.
I would say, that you will definitely get the antenna to work, I don't think that's a problem.
You need to think about automating those spools or at least remote controlling their winding/unwinding 🙂
Once that's cracked, automation is pretty straight forward (SWR sense etc.)
Keep innovating. That's what makes this hobby of ours interesting!
73
Bruce G4ABX
Thanks Bruce. Your feedback is always appreciated. The automation part needs a lot of work mechanically and I do still think about this regularly. Kind souls like yourself could help with the control. The big issue is keeping sufficient tension on the wire. First I need get it built as is then test on air.
Hi Colin, I just ordered a couple of the 39mm Ferrite cores, interested in what box and other hardwar you can recommend tnxs for the interesting "evolution" VK2FLN (John)
The box is an RP1065. Various manufactureers sell them. I dont have a bill of materials but most of the items are pretty obvious.
How will you handle the wire movement at the top of the supports Colin? Some kind of pulley maybe.
Spot on Ady. I will use the HD Sprenger mini kite blocks for this.
How is the positive side of your transformer, electrically being connected to your spool of stainless steel wire? I see the bolt going through the center of the spool, but not seeing how it's getting to the stainless antenna wire?
The stainless wire is crimped onto a 6mm ring connector. Loosen the wingnut and it spins feeely. I need to make a video on this as I get a lots of questions about it.
I like your idea. If you used aircraft safety wire, stainless steel wire used to put through nuts and bolts to keep them from moving. It comes spools don't remember how much is on the spool, but it should be enough to make a lot of the antennas , listed on Amazon. There are different sizes. 73 W4DES
Thanks. I wire here already. Its a 1mm diameter 316 stainless and is ideal.
I molded this (40m) and indeed it has the pattern of a half square but naturally on just the design band. It is rather directional on 20 and 15 meters. 10 meters shoots straight up however so it's not good for that band.
Yes its not a miracle antenna. The harmonic bands are a bonus.
This is a very interesting idea!!! I have no feedback for you, because I'm a noob! But.... I am experimenting with my own EFHW, and have everything I need for the coil (toroid, wire) except for the capacitor and the PCB, but I think I'll use a project box like you are doing and won't need the PCB? I'm certainly going to watch your project with great interest!!!
The PCB is just an indulgent extra that looks good. Go with this core and use the 2 primary windings and 15 secondary windings and your good to go.
Yes you're as mad as a box of frogs, but it great to see someone actually trying to advance our hobby. I came across your video on Monday a d the new cores arrived this morning! I'm going to try your design. I was thinking of stacking two cores ,have you tried that ? would appreciate hearing your thoughts , I want to build the best antena I can to operate from my motorhome in the Peak District . Have a 12mtr spiderbeam pole .
Yes I'm pretty daft. You can stack the cores but its counterproductive for higher bands. You will make 160-40 more efficient by an insignificant amount and literally kill efficiently 20m up.
I think its a great idea!
Just need bigger real estate 🤔
@@MM0OPXFieldRadio Come on over. I've got plenty to share.
The half square antenna designed for use on the 20 m band (about 20 m total wire length, 5 m up, 10 m across, 5 m down) will I think give you some gain on the 15 m and 10 m bands too. So I don't see much point in your complicated adjustable length version.
On the 10 m band the two vertical sections are each 1/2 wave long and the horizontal section is a full wave long so the two vertical parts are in phase and the antenna should have gain in the broadside direction. perhaps even more than it does on 20 m. The two halves of the horizontal section have currents flowing in opposite directions so radiation from that part will have nulls in the broadside direction and thus not change what you get from the vertical sections all that much. The horizontal part will have lobes at angles to the wire and the overall pattern in such directions will be somewhat different from what the verticals alone would have produced.
On the 15 m band the two vertical sections are each about 3/8 wave long but the horizontal wire is 3/4 wave long so the two vertical sections will now be out of phase, unlike on 20 m and 10 m. Thus you will have an end-fire antenna with nulls (for the radiation from the vertical sections) in the broadside direction. There should be a small amount of gain in the direction of the horizontal wire, from the currents flowing in the vertical portions. The horizontal wire will have current in its two outer 1/8 wave portions in phase with each other but out of phase with the current in the middle 1/2 wave portion. It will radiate mainly in the broadside direction because the current in each of those two outer 1/8 wave portions, though in the wrong direction, is small in comparison with that in the middle 1/2 half wave section. So I think it would be a useful antenna on this band too.
On the 40 m band the whole thing is 1/2 wave long with currents in the two vertical 1/8 wave portions out of phase with each other and with those portions physically 1/4 wave apart. So there will be negligible broadside radiation from the vertical portions, both because the currents in them are small and because they're out of phase. Because they are physically 1/4 wave apart, there will be some radiation from them in the direction of the horizontal portion, but not much. The horizontal portion itself is only a quarter wave long, and very low, so it will give you a cloud-warmer, though not quite as good a cloud-warmer as a half wave horizontal wire would be.
If you remove the unun and intead feed one end directly from your coax, and supply a good radial system, you will have a (very low) quarter wave wire on 80 m. Better than nothing, on that band, though not by very much!
David VE7EZM and AF7BZ
Thanks for detailed reply. My primary interest is as a gain antenna as a mono band. If I can set this up beside saltwater it will perform even better.
@@MM0OPXFieldRadio If you make it about 20 m long total, voltage feed it at one end, and do not alter its length from band to band, you'll have good gain on10 m as well as on 20 m, and a modest amount of gain on 15 though it will be in line with the horizontal wire and at right angles to the best direction for the other two bands. And you won't have to adjust anything for band chnages (if you use a high ratio unun to feed one end). It should work great next to, or better yet in, salt water.
David VE7EZM and AF7BZ
what are the markings of the core used for the transformer?
Its a 2643251002
Looks like those 6m poles are no more. Only got the 10m in stock, and told me in email no more of anything else expected! Would have been perfect for the 5m height needed for a 20m half square!
I know! They only have one order arrive per year of these, usually in April so keep an eye next year. Luckily I have 4 of these now. I'm going to as you suggest.
Did you find a UK supplier for that form factor of ferrite core?
Unfortunately not. Digikey has a minimum £35 +vat order value then you get free shipping from states and its 2-3 day delivery.
@@MM0OPXFieldRadio Thanks. I have only found them available from the USA.
Yes, they are shipped from the USA but service is superb.
But you are feeding it through an inductor basically when you wind it, so I'm not sure how does that work
Nope its not an inductor as I'm using bare stainless steel wire so its not seen as an inductor. Been there done that and made that mistake years ago.
80m EFHW will also give 30m, 17m, 12m.
Very true 👍
Since it has been over 3 months and of all your videos since, none are a follow up, is It was a flop! Ask I watched, I was hoping for a surprise that it would work as seemed unlikely.
So because its been over 3 months you make that assumption. You know whats happens when you assume things? Quite simply I havent been back to this. I have the wire cut and the mounting plate template made. I'm not at youtubes beck and call. If something doesnt work then I will share this, I've nothing to gain by hiding any details. It wil happen but when all the elements come together.
Sorry, no modeling, no empirical results, just a hunch makes your video description too presumptuous. I am all in favor of trying new things and finding better ways to do something, However, to declare your idea as a SMARTER antenna us not very bright on your part and becomes click bait.
Do your experiments, model the results, then do some A/B comparisons with another comparative antenna, at the same time and using the same equipment then claim victory.
My point is not to insult you but to make a constructive criticism.
I have been licensed since I was 16, now 66, 50 years as a Ham and also an E.E
Good luck with your project.
Now, some opinions, since you are suggesting 2) 1/4 wave runs, spaced 1/2 wave apart, you are adding some vertical component to compliment the horizontal run. Much like an inverted L does. Without modeling this config and doing many field strength measurements, it is impossible to say what the second 1/4 wave will do the signal at various freq's. When you electrically connect 2) 1/4 wave runs via the 1/2 wave rub, it becomes a single antenna. If you have the real estate, an inverted L will most likely be a better arrangement. Again, good luck es 73, Glenn WA4AOS DSM Labs
Glenn, something brought you in to view this video in part or entirety so the description has done its job and for that I'm glad. At no point am I trying to deceive or pretend to be smarter than anyone else. If you have a search for other content on this subject you will find I have done nothing original with feeding a half square antenna at the base of one of the verticals, if you look deep enough you will even find videos showing the modeling that demonstrates the potential. At what point did I claim a victory? should I not start a discussion without months or even years worth of experimentation under my belt, perhaps a written paper? The only thing I have done that I haven't seen others do is use a variable length radiator on a half square (though I'm sure someone has). I want to start a discussion and spur on some others to perhaps try this or even continue the experimentation. It's prompted you to add to the discussion and for that I am glad also.
@wa4aos Ah the beauty of amateur radio. Never a shortage of windbags and especially windbags critical of a video that have no content themselves. Saying someone isn't very bright....isn't very bright and makes you look like a dire AH.
Completely agree, I was watching it wondering what the point was. This antenna is no better than the EFHW as we know it.
Every location differs as to which kind of antenna could be best to use. For example, people go wild for high gain colinears on VHF and UHF when a simple Slim Jim outperforms them in some locations.
HF is the same. It depends where you live as to what you can fit in.
I do not see the point in this design, so would not waste your time.