Ham Radio: Make Your EFHW Into a DX Machine!
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- čas přidán 28. 05. 2022
- The EFHW is a very adaptable antenna as we can configure it in so many ways. By doing this as a half square we can make the harmonically related bands perform really well for DX!
Connect with my channel by subscribing and commenting. 73 - Věda a technologie
It‘s my favorite antenna. Use it only on 15 and 10 m. Have fed it both ways, but prefer it lower corner and 49:1.
One thing you didn’t talk about is noise. Where I live I had about a S 4 noise level and with the half square it’s gone. It’s worth trying guys!
Thanks for your work de HB3XBL 👍🇨🇭
Thank you. It’s a useful option as a multiband antenna
Hi Tim, I put a cord on the end furthest away from the transformer and pull it out horizontal for 40m as an inverted L, when I want 20m and above, loosen the cord and the sinker returns to the bottom and back to the ½ square.
VK6MB
Great example Mike
Long back I had an antenna like this which was distroyed in a cyclone. Right now i have an efhw and I am trying this conversion. Sharing to our group. Thanks 🙏 73
I hope it works well again for you! 73
This is such an informative video, Tim. Every time I see one of your videos, I come away saying, " Oh, I need to try that this week!" My XYL isn't as enthusiastic as I am, but hasn't yet demanded that I stop. 73 from America!
That's too kind Abraham! My XYL is the same - just shakes her head with a smile on her face. 73
Thanks Tim, built one as described and working really well, especially on 15/10m.
Fabulous!!
@@timg5tm941 Just a quick followup, now worked 153 DXCC on 15m and 164 on 10m, predominantly using this antenna fed with 50W. Really pleased with this fantastic antenna especially given how easy it is to setup and how well it performs.
It would be really interesting to model and then try a 12m version that worked on 12m and 6m. Transformer a little more challenging probably but ....
Any thoughts on sharing your MMANA-GAL models as you publish the videos so we can follow along and play with options?
Thanks again
Nice one Tim i use this antenna fed from the corner and 10-15-20-40 and 80 it really is a Machine :)
Nice Dave. 73
Those are awesome
Simple
Vertical polarisation
Low angle
2 1/4 Vertical
4 db gain over one Vertical
No ground radials
12 db broadside to end null
Just use current bslun 1 to 1 at one of top corners
I will put one up for 40m to europe
I avoid radials
Its 1 wave total
1/4 1/2 1/4
I think dipole null is about 8 db depending on height
Thanks for the info
The Half Square works very well. I have used the form on the 80 meter Band with good results compared to an 80-10m band ground plane monopole vertical mounted over tuned radials.
You can imagine that the 80m version might be quite high, needing 20 meters of height plus head-height clearance. Having only 15 meters of height available, the lower end of each vertical element was bent inward toward its opposite. The antenna then looked similar to an 'omega' symbol. Since current is greatest at the driven end of a vertical element, this made little difference to radiation.
I used the antenna when serving as net control for a nightly 80m phone net working stations from coast to coast to coast in Canada with me at the centre. According to signal reports from stations more than a couple of hundred miles from me, the antenna was superior to my 80-10 meter vertical except when working northern stations at right angles to the preferred radiation directions. Then the omni-directional monopole was better. Closer in stations saw no difference between my monopole and the Half Square. On receive, there was an improvement in received SNR using the Half Square compared to the monopole since the Half Square is bi-directional.
I also built two Half Squares for the 20m Band with each at right angles to the other allowing me to switch between East-West and North-South patterns. I did not use the pair long enough in order to draw conclusions worth passing on.
Give the Half Square a try!
Fabulous information.. thank you for sharing details about your excellent antenna
Thanks for your videos! I hope to get my hfkits efhw up over the next few weeks. (Straight line at this stage) Going to use 6 meter, 50mm pvc pipe (guyed) to get it a good height above the metal shed and house roof.
Sounds great!
Made one this last week. If works very well and low SWR at all the right places. Also stealth and pivotable to give directionality.
They are a great design aren’t they!
@@timg5tm941 It works really well, not as good as my 5/8 vertical on 10/12, but it rocks on 20m. Now building a G7FEK and a Moxon for 10/15.
Brilliant antenna I use one portable now and again on 20m and managed zl on it from the UK. M0cql
Agree they are a good one wire antenna for sure 73
I have used mono-band Half-Square antennas with great success in the past. I did try this scheme out on my 133' EFHW, and rehung it as a half-square for 40M (32' vertical sections with ends 6' off ground), and tested it out on a DX contest one weekend. For any of the 40M DX I chased it was no better than rotatable 40 dipole at 50' on tower. The next weekend I rehung my 133' EFHW horizontal at 43'. If was a fun experiment, and antenna tuner tuned it on all the same bands, but I did not see enough benefit in my setting.
Good info thank you 👍
Wow. food for thought! I was ready to install a regular end fed half wave at 80m (i can just about get 40m horizontal in) , however I am now wondering if i will actually use 80m that much anyway. I have a dx commander (multi band 1/4 wave vertical) and by your reckoning Tim, i should get better gain with this square on everything above 40m? What do you reckon?
Give it a try!
Well done. Well explained..What about a half wave end fed (for 80 meters)in an L configuration 50 or so feet vertical, 80 or so feet horizotnal, fed with 49:1 unun ? Pattern on various bands please?
Definitely works .. I’ll try and model that
Have you used this antenna in the field? As Peter said earlier, have you used this type of antenna and do you have a video of it in actual use?
Hi Paul - just modelled at the moment.
Tim how long will an endfed halfwave need to be on 80 /40/20/15/10. Mine is currently configure as a half square and I get it squirting RF more towards South America and Europe .
Hi Simon. The full length efhw for 80-10 is 132 feet or so long (40 metres). Remember that it will still be a cloud warmer for 80m but it will begin to fire low angles , great for DX ,40m and up. Remember too that it’ll need to be 10m above ground and be 20m long. 73
Thanks for the video - did you simulte the pattern and the gain for 17m, 12m and 10m as well?
These came out in 1996 and were ran like a full wave loop, but instead fed at a top corner, with 1/4 wave of 75 ohm coax (-velocity factor), then 52 ohm coax to radio. They were monoband, but using a lower freq (20m for example) one on higher bands, with a tuner, made a very pointy x pattern of gain. Set 45° to North, it had lobes favoring N, S, E, & W.
Not yet but I will and see whether a 9:1 unun might be an option with tuner
@@timg5tm941 I use 1:9 transformer with a manual tuner and it works well even at the impedance peak near half wavelength. TS590's internal tuner doesn't match the 1/2WL but works well on others. My 1:9 is a trifilar winding on FT140-61, 15t (about 30-33uH each winding). I am looking into a cascaded Guanella 1:4/1:9/1:16 transformer to use the internal tuner on all bands.
Very interesting vlog there Tim! Have you built this or is this just theoretical modelling? Be good to see it as a photo in the flesh.
Hi Peter - just modelled for now. But will be tested. 73
Ok. Right now I'm running a hwef out a 3rd story window horizontal to a tree across the yard. There's a tree outside the window. If I can get it vertically maybe 5 more meters up that tree the only other option would be to slope the rest. I I wouldn't be able to get the full half square, but would that effectively get me more dx? It gets 1:1 on 40 and 10 horizontally, but definitely takes some tuning for 20. Would it help the tuning for 20 as well??
It depends a lot on the height, how high is your sloping part of the antenna from highest to lowest? Also, how long is it and roughly which parts of it form the sloper?
@@timg5tm941 It's roughly 66ft long, running horizontal out a third story window about 30ft up. If I can get some vertical from window to high as I can get in tree right outside (maybe another 5 meters), the slope down from there could be whatever would work best. Trickiest bit would be keeping the radiator away from the branches... Not sure what the advantage would be for the work to get it up there.... Thanks Tim.
I tim the half square fed at the bottom With 49.1 is the other end of the transformer earthed or would a counterpoise be better
Thanks Bob G4PEN
I’ve found no benefit from earthing or running a counterpoise as the impedance is so high at the base. A 49/56 or 64:1 would all suffice.
@@timg5tm941 Thanks Tim erected it yesterday and it is working really well Cheers Bob G4PEN 73.s all the best for New Year
You too Bob 73!
I have to try this out. If it works I'll make a video on it.
Thanks!
@@timg5tm941 By the way, have you tested this setup, or just modelled it?
@@timg5tm941 Testing the setup right now. Performs slightly worse on 40 and 20 than my regular EFHW sloper config. Significantly better performance on 15 and 10 in my totally non-scientific test with WSPR and FT8. I'm having both antennas on a switch, so I try do do some A/B testing.
ok, what is the optimal length wire length, vertical height, and horizontal run, for performing well on 20m like it does on 10m?
If you want to repeat 10m you will need to double the dimensions so that the overall antenna wire used is a 2 wave on 20m. So 10-20-10m (double my version). 40m would now be what 20 is in this video. 80 would be what 40 is in this video. PLUS you’ll still have 15, 10 AND perhaps a reasonable match on 10,12,17
Here's a thought and I'm aware I'm ready to be flamed here and told I'm being stupid but...
If the distance away from the ground affects the radiation pattern then what about theoretically adding ground radials ABOVE an antenna? I know for HF that's impractical, I'm just thinking theoretically. Can this be modelled?
Hi Simon, it can be modelled, but, in this case it would de-tune the design. 73
Is this the same as the conner fed curtain antenna
Very similar!
I have a 75-10 M EFHW configured in a flat configuration from 35 feet at the feed one end and 55 feet at the far end (the land slopes away from the feed end) using a hefty 49:1 Balun coax fed with LMR400.. It is a great antenna for DX. However it is a bit more noisy than my 80-10 M Horizontal Loop. Will reconfiguring it with the 1/4 wave vertical sections at both ends even make it more noisy? Usually, you do not GET something without GIVING something up.... the NO FREE LUNCH rule of antennas... I wonder if any of you who have experimented with the 1/4 wave V 1/2 wave H and 1/4 wave V config can share their experiences on 20, 17, 15 and 10 meter bands. Thanks Art W1SWL
Hi Art. I find a vertically polarised antenna, whether hand or quarter wave, tends to be noisier at home.
@@timg5tm941 Hi Tim: have you modeled this modified EFHW antenna in MMANA? If so I would love to see the results of that Model... as a flat then modified as a half square.! Art W1SWL
@@arthurgumbus3969 hi Arthur, did you mean as a flat horizontal and then compared with the half square?
@@timg5tm941 Yes as a flat horizontal model THEN change that to a half square and see the results on MMANA.... You are really good with that program so I leave the driving with you. I think it would be a great follow on video... with some education for we aspiring MMANA novices. I say go for it!
Will it matter how thick the wire is?
No not really
All these itty bitty crossover baluns have the annoying advantage of getting the feedpoint out of the shack, and shielded coax to get there. Not much more than 10 years ago, a tuner and a longwire did this, and the idea of the antenna starting at the radio was not kosher, and was thus too close to interference sources.
The next step was balanced line or a combo G5RV, but those were eyecatching dipoles, that still needed a tuner, and balanced line was a bugger to run out of the shack, though quiet, still radiated alot of harmonics on tx.
These lil baluns just absorb harmonics, use 52 ohm coax, to run to feedpoint, and can be coax tuned anywhere, or trimmed to run free on at least 4 bands.
Thanks for the info
What would be the length of the 11 m BAND antenna or what is the mathematical equation for figuring it out say at 27 555 megahertz
Full, half, or quarter wavelength?
27.555 divided by either 963 (full), 468 (half), 234 (quarter).
e.g. - 234/27.555 = 8.492 feet.
I hope this helps.
KD8EFQ/73
P.S. I work 11 meters and the "gray bands" as well 🤣
24 Southern I-da-Ho 🇺🇸 2 WE 024
As below...
Let not forget voltage feed antenna at there feed point can be dangerous with upto 5kv at the feed point,,children and animals should be kept back from the feed point at all times.
Very true
i.e., An inverted U.
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How would it do on 11 m? All you hammers out there only talk about ham radio but some of us out here that like to play on radio use the CB band. So how does it do on 11 m and would it be worth building this antenna for CB? I mean you guys have got the licenses and we're the ones that look up to you. But you all ignore us when it comes to talking about antennas.
Try 35 feet initially (divide by 3.28 for metres). If needed trim the base of both vertical elements to bring it into tune. Should work like the 20m band does on this video.. most gain broadside.
@@timg5tm941
Thnx😉