Smitty Working On SOMETHING: Fan Dipole Construction Techniques
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- Опубліковано 10 жов 2024
- In a twitter conversation with @ke8dnu, we got to talking about fan dipoles. It was easier for me to shoot a video on how I built mine than to try and explain 280 characters at a time.
I shot and edited this video entirely on my phone, the second or third time I’ve done this. I also found out how to add text to video, so I made my own peanut gallery and corrections.
Let me know if you have any questions! Also, tell me if you end up building an antenna with info from this video. Knowing it helped someone is what keeps me going with these.
Cheers! Be good humans, everyone. :-)
The first amateur radio antenna I built when I was a Novice was a fan dipole for 80 meters up to 10 meters (80, 40, 20, 15, and 10). It was a colorful antenna, red, white, blue, green, and black, all scrounged from a construction site dumpster, brought home and spliced and soldered together. I didn't use a balun, rather a coaxial choke. I had no difficulty tuning up with my Heathkit ATU. This was when the bands were open most of the time. My station was QRP CW and most transmissions were 3 watts or less. My first 50 QSO's were close to 5 watts but I soon decided to back off on power so I wouldn't blow my final transistors. That was a great antenna. I have used many different types since then, though. 73 KB8AMZ
Great job Mark!
Thank you very much for helpful description
Your camera work on the roof of your house gave me the heebie-jeebies. Anyway, nice job and thanks for the construction technique ideas
Heh. I have a healthy fear of the edge of my roof. All the camera work here was done from the center ridge line. :-)
UA-cam put you on my play list again today, been a year and I am still pondering my various build projects, my 17 years old pup passed a few days ago so his no longer needing me in sight and smell distance is freeing me up some to maybe get something done. Your fan idea is still in my thoughts, I discovered certain plastic or PVC pipes can be used with my no hole roof satillite mount stand to go at least 35 feet up so some kind of wire antenna can be center supported with it. I still want to try the idea of using the non-radiant or counter poise side of a fan dipole with a switch making it possiable to switch from horizonal radiant elements to vertical feeding it at the top of the pole coming down at least for 40, 20 and maybe 10 meters, using 40 also on 15. Just a theory, who knows if it might work? If so anyone feeding a dipole and supporting it in the center could add a vertical componant to their dipole. Just something that seems to return to my thoughts ever so often. Also couldn't 30 meters or 10 meters long hormonic be nears 6 meters , if so your friend wanting a 6 meter might be able to use the 30 meter elemeny much as the 40 is used for 15? Idon't use 30 meters so can't try it?
Sorry to hear about your pup.
Thanks Mark, I likely will be trying one before long. I have a strange idea of doing one except making the driven go down a pole and using the non-driven like a counter poise, so it would be a vertical with the coax attached at the top . Kind of like a DX COMMANDER vertical except top driven and not having so many radials. Also the idea of coming off a metal roof with multiple driven elements going to trees much higher has entered my mind. I have room in my yard long enough for one side but not a stretched dipole. Of course the lower take off angle of a vertical for DX appeals to me.
I’m not sure I understand. You mean like a 1/4 wave ground plane, but up-side-down? By definition, if one element is driven and the other isn’t, that’s not a dipole, that’s a ground plane. (The “not driven” side is the ground, or counterpoise.) And usually you want the ground or counterpoise below the driven element, though I confess I’m not sure if that’s just convenience or for some electrical reason.
I’m all for you trying it out and telling us how it goes! But I’m curious, why top-feed the antenna? Is it easier to construct in your situation somehow? Or just experimenting with something new?
@@SmittyHalibut Like I wrote a dipole full length is over 130 feet on 80 or over 66 on 40 so space matters. I wanted a vertical dipole but going 66 ft up for 40 or 130 for 80 is also not doable, but I can top feed for lower bands and use the single counterpoise not 130 like some many think is necessary for a vertical. I stay confused how a dipole can be a single wire equal to the driven element yet a vertical needs many times that to work. A vertical anything antenna has a much lower angle of radiation and is much better for DX . A DX Commander is a fan vertical yet still requires a large array of radials to work, by moving the feed point to the top, only a single non-driven counter poise wire for each band in theory should work. That is my reason for this approach.
Thanks for the great video Mark! I've always wondered how people were putting together their fan dipoles. I am currently running a multi-band OCF but someday I hope to build a fan dipole.
I hope this video help! :-)
They always do! I love hearing you on the 360 podcasts as well. de VE1XT
im actually in the middle of 3dprinting a bunch of spacers to build a 40/20/15/10 dipole
Nice! Let us know here how it turns out. :-)
Like the video. Thanks for posting. I use a doublet myself but if you have the room then fan dipoles work well. Hopfully showing an improved version of my doublet on my channel soon. 73. p.s. - subscribed.
I love the floating Floyd Rose reference! 73 WSØX
Marc White i used to have a floating bridge and could never get it tuned right. I’ve gone with static bridges, or tremolos that rest solidly against the body (is there a term for that?) ever since. I’ve never found myself really using the ability to pull my tremolo anyway.
I’m glad that at least someone caught the reference. :-)
Samp problem here. I cut off 20 and 10 because they would never tune. Just have 80, 40 and 30 wires which tune fine . Not sure why 20 and 10 would never tune no matter how much pruning or adding back i did .
Good video, I wonder if the height still allows NVIS use, debating if I WANT GREATEST HEIGHT or go lower and hope for better shorter range 100 to 300 miles or so for day time 40? I have a roof mount stand normally used for satellite dishes that can anchor another pole with 30 or so feet up available, plus some of the large coax reels used by cable companies for their hard line ( got 4 of them along with a supply of the ends to short to use for them) that a plastic pipe can be just stuck in the middle to hold them up to use at the ends so some flexibility. Hurricane Michael did a number on my community blowing down thousands of trees and also requiring the cable companies to run new hardline. Comcast replaced their entire system taking down miles of hardline. i am even considering using some 75 ohm hardline as the feedline burying it to stop common current issues or going part way and then making the last leg rg8 or other 50 ohm.
I wonder if you could add the upper bands by making them an inverted V -- common feedpoint for both the existing fan dipole as well as the fan inverted V, but a higher pair and a lower pair of endpoints, the higher for the lower bands and the lower for the higher bands (as inverted V).
Yes, absolutely you can do that. In fact, many designs I’ve seen suggest a much wider “fan” than I have. The more space between the elements, the less they’ll interact and affect each other when trying to tune. They don’t even need to be in the same plane, but obviously this will affect radiation pattern of the different bands.
Hey Smitty, Happy Thanksgiving to you and yours! 7 3! I'm a dipole fan, does that count? I thought not 😁😀👍
So how has it worked out after 5 years? I am adding 60 meters to a 40 meter dipole and without seeing your video I also used PVC spacers. I was wondering if the shorter element could be put on the top rather than below as most fan dipoles are constructed. My purpose is for NVIS local and regional nets.
It worked very well for the time I had it up, but I ended up taking it down several years ago for various reasons. There's no reason the shorter element can't be on top, but since you'll generally be tying off to the longer element, it's easier to let the shorter ones hang down. But if your construction method makes it easier to put the shorter ones on top, there's no reason that can't work electrically.
@@SmittyHalibut I think 3 is the best number of bands. This is a great way to have a reasonably priced reliable multiband antenna that's quite easy to build.
Hey Smitty, new sub and new ham here. I am building a fan dipole and am searching for construction techniques. this will be my first attempt to get on the HF airwaves from my QTH. I am planning 4 lines (80, 40, 20, 10, with 15 resonating on 40 with 3rd harmonic). I have heard that I should keep it to 3 lines because of what you mentioned. The separation, I am planning will be roughly 5” between lines. Thanks for the advice and techniques you used, they have helped me finalize my plans. I know this is a few years old and I am assuming your are still on here. My main question is how do I keep tension and I think you answered that in the video. Also, tying rope to the next available line with rope is what I thought of doing. Another question I do have is how do you keep the separators from sliding around on the lines? Silicon or hot glue? I am going to start drilling and measuring cable, and making my feed point this weekend. If I am successful, I hope to see you on the air and thank you for your input. 73 de KI5HXM Brent from Texas.
Hey Brent, sorry for the long delayed response. Life has been a bit chaotic this year and this one slipped through the cracks. I don't have anything keeping the separators in place, they're just held there by the tension in the wires. I haven't had any problem with wind moving them around, but if you walk up to the antenna and move it with your hand, it moves easily.
Granted, this is with California "weather" (put in quotes on purpose.) So any place with REAL weather might have a harder time with that. In that case, something like what you suggested would work: hot glue, silicon, rubber grommets, whatever. So long as the material isn't particularly conductive, and you keep it relatively small, it'll be fine.
@@SmittyHalibut thanks for the reply. Yes it has been crazy here in Texas. Haven’t even got my ride on the HF airwaves yet. No worries on the delay. I have thought about some kind of silicon or rubber with maybe a zip tie holding it to keep them in place. I have lots to learn. That is why I am in this hobby. Thanks for your videos and input.
ZIP TIES! Brilliant. Yes, that would work well too.
In your tee shirt, do you find...
Serenity? Thought so👍
90% of hams play guitar. Change my mind.
You’re not wrong. Playing harmonica on the guitar are how I visualize what’s happening in an antenna.
Thanks for this Mark. Im in the process of putting together a fan dipole with 80m and 40m to begin with, might add 20m at some point. Your video has been very helpful from a practical design perspective. I will let you know how I do once it is up - I currently have two separate antenna's that I want to combine on a single feedpoint. btw, did the gent that recommended against knots ever get back to you? de VK1FCLU...73
Not that I've seen.
It'll blow your RECEIVER? Right. #dontfeedthetrolls
I had a 10, 12, 17, dipole I called a porcupine. Common center but antennas went different directions.
It worked real well until the roofers cut it up.
A ham buddy of mine saying that have a balun close to the metal pole isn't good at all. Does that affect the antenna at all? I have an 80 meter windom and the Balun is on a standoff so it is not directly on my metal push up pole. 73 KA9WLU
Not that I've noticed, but I also don't have any precise measurements. I think it would depend heavily on the type of balun used. Anything with a toroidal transformer will be fine since all the fields are kept internal to the toroid. A linear (like a bar) transformer will have magnetic fields outside that might cause a problem.
But I think this particular balun is just a bunch of ferrite beads around the coax jacket; you're not so much trying to make a precise inductance that would be negatively impacted by the presence of steel, but make "a whole lot of inductance" to choke off RF. So adding more steel near by is unlikely to impact that too much. But, I confess, I'm making that last part up, I could be wrong.
@@SmittyHalibut Ok thanks Just was wondering. I'm trying to get back to ham since a recent divorce last year. I'm working RF issues in the shack and might have make me a RF choke.
Have your neighbors commented on your antenna?
Only the other hams in the neighborhood who have stopped by to say hi. No one has complained. What you see here in the video is the back side of my house, so it’s much less visible from the front.
measure once, cut twice... and never but really never use a knot on dipole. It can blow your receiver instantly.
Janez Novak care to elaborate? How?
WRONG