When is a Dipole a Doublet? Let's Take A Serious Look!
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- เผยแพร่เมื่อ 10 ม.ค. 2021
- As ham radio operators we are always interested in antennas. But there is still some confusion about the Doublet and how it differs from a Dipole.
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For years and years I used coax and chokes and all that. The first time I put up a doublet, the difference was so amazing, that I've never used coax again. My overall radiator length is 102', fed with 14 ga. 450 Ohm window-line (aprox. 70') which i run through my outside wall, terminated into 2 female banana-jacks that are mounted to a piece of plexiglas screwed to the internal sheetrock plaster-board. I have a very-short window-line jumper with male banana-jacks going to the tuner. When the antenna is not in use, I have pair of ground wires with male banana jacks that plug into the antenna for and go to a very-heavy ground buss with ground-rods outside. The center-feed is on a 50' tower side-arm.
Everyone yelps about taking window line through an outside wall! My wall is stucco on chicken-wire, which I cleared away where the window-line goes through. I then formed a drip loop with the window-line, and sealed the outside with a generous amount of silicon against the stucco and part of the interior of the inside part of the wall. I checked the performance on all bands both outside and after the installation and the was NO-DIFFERENCE period. This way my balun inside and I have only coax from the tuner to the radio. I run all bands 80-10M completely with exSWR. So, try this amazing antenna--you'll love it!
THANK YOU FOR LETTING US IN WITH YOUR THOUGHTS AND IDEAS PETER!
I HAVE TO USE A 2 X 10M IE 1/2WAVE
OM 40M BAND. I HAD A 80M LOOP BEFORE SOME YERKS SLAUGTHERED IT WHEN THEY REBUILT THE BLOODY ROOF! 160-6M WITH 450 OHM WINDOWLINE - ABSOLUTELY AMAZING LOOP ANTENNA (83,0m or 273feet WITH 23m 450 Ohm feeder! It was Marvelouse!
The definition of resonance is when all reactances have been adjusted to cancel each other out and is purely resistive
With the tuner adjusting the capacitive and inductive reactances to cancel each other out and the system is purely resistive, the tuner has tuned the system to resonance!
Remember Louis Varney explained how the ASTU, antenna system tuning unit that he liked to called it tuned his antenna system to resonance
No doubt, you are a natural teacher! 73 AF5U
Many thanks for that. Take care, 73 Peter
Very well explained! There has always been confusion concerning the question of "dipole or doublet"? 73!
Many thanks. 73 Peter
Great video. I've narrowed down my choices of my next wire antenna to two: ZS6BKW or a doublet, which of course the only difference being one is resonant and one isn't. Decisions decisions! I have a good LDG AT-1000ProII Auto Tuner so I am leaning toward the doublet. Plan on an inverted vee configuration with about 90' for each leg. Will report back when complete.
Thank you for extending this.
Many thanks. Peter
Would it be preferable to use a measured 67ft wire section and see if ATU can tune for 80, OR use as much wire as will fit in the yard space divided evenly and use tuner? I’ve got potential for 90-100 foot run depending on how cooperative a large gumtree is! Fed with ladder line into 1:1 balun. Vk5LTD
Thanks for this Peter, I've been thinking about a doublet for a while and this has helped clarify a few points. My new shack has 150ft on either side (300ft total) available for erecting a doublet. I would only be able to raise it to 25ft at the feed point and for most of it's length but one end could go to 40+ft. I suppose the best way to find out is to try it!
Yes give it a go.
First 18 seconds hilarious😊🎉😂
@watersstanton Peter I love the videos! I am considering a doublet for nvis on 80m and 40m. Have you experimented with this concept? Do you have results to share?
Excellent! Thank you
You are welcome!
Thanks for this and all your other great videos. Definitely my favorite ham channel. I am on the other side of the pond, and wish your store had a branch in USA.
Many thanks Karen. Great to hear from you. 73 Peter
It might have been nice to show the voltage maxima in a dipole. There are two of them, at opposite ends. Hence the name, di-pole. There the impedance is high. In any case, if the total length is resonant (a half-wave), it's still a dipole even if it's end-fed.
A doublet is just that. Two legs. Not much else to say about it in general. An endless supply of individual cases.
Great vid again thank you so much for taking the time to make them so easy to understand and take on board..keep them coming .john m0asn
Please keep these doublet videos coming, Really like them and the spy vids. Reminds me of the ghost story's from one of your fellow countrymen. Thanks from Merica.
Many thanks. Peter
Great description Peter
I have had an argument with my friend who seems to have it in his mind that a doublet or g5rv needs to have a specific length of coax between the ladder line and the tuner. I can find nothing to support that however this video supports my argument that there is no set amount of coax needed. I am running a standard g5rv with a 4:1 balun and about 20 feet of rg-58 into a LDG it-100 and a IC-7300 with great results. My second antenna is a zs6bkw with a 1:1 balun and it loves 40-10m . Both antennas are inverted vee configuration at 40ft at apex and 10 to 12 feet at the ends. Now if only the bands would cooperate a little better. 73 Jim ve4jim
Hi Jim, G5RV ladder length is only to get a reaonable match to coax. Has nothing to do with antenna performance. Balanced line all the way back is better if you have an ATU. 73 Peter.
Hi again Peter. The ladder line was not in question, it was the coax from the ladder line to the shack. My friend firmly believes that it has to be 70 feet. Here you clearly refuted that and now I will have the greater job of encouraging him to watch your video. All the best Peter 73 Jim
@@watersstanton it's interesting that Louis Varney states that the ladder line is a make up section and that it doesn't really do any impedance transforming and that the antenna system tuning unit tunes the antenna and feedline to resonance
Peter, I am planning on buying a metallic narrow boat and looking forward to putting together an all-band rig (IC-7300, IC-9700 combo) on it complete with two multi-band antennas. For the HF band, I was thinking about an HF loop. For the VHF/UHF bands, a tri-band vertical and a portable Yagi for the occasion QRP with the IC-705.
My questions are: what effect a large metallic surface - that the boat is - will have on SWR and radiation patterns for the loop and the vertical? Should the rig and antennas be grounded to the metallic hull? Narrow boat manufacturers recommend against using the hull as a ground for electrolytic reasons.
I am a big fan of your channel and thank you for all the useful information you contribute to the art.
Warm salutations from grid EL97tf
Hi there. A boat is a great base for antennas plus the water around the boat. As far as radio is concerned you can safely use the metal of the boat as an RF earth. You should get some great results. 73 Peter.n
Thanks for all of your videos. Sometime can you speek on EFHW Tuners. Do we need them.? Thanks K7WHN.
I have done quite a few on EFHW. They are all on this channel. Peter
I don’t know what kinda ladder line you have in the UK but here In the States unless it was tv dual line from the 1960-70s it’s junk. Copper clad stainless steel and the coating is a mil thick if that. Best to look at Facebook The Toad Harbor page explains how to make home made open feed line. American farm works makes electric fence ribbed isolators and 13” uv resistant wire ties a roll of 12awg solid core THHN coated copper. 500’ spool should give you 130’ each leg of the diepole and 120’ feet left over for the feed line. Add in a balance tuner like dentron super tuner and you will have the best multi band antenna
KC3ONO
Hi Kevin. The popular balanced line here is 450 Ohm semi airspaced which works and lasts well. 73 Peter
I got a 20m horizontal loop in loft of third floor flat fed with ladder line, works well 20-10 and tunes up on 40 with small bandwidth, I cannot work out if it will work better if I split it and turn it into a doublet in the shape of a halo antenna, internet gives me two different answers, both are called skywarmers and DX antennas. Any suggestions? I know if I split it tuning on 40 will be better.
I see no reason for it not to work. I woukd expect at least as good performance as you have now but as yiu say, it will add 40m. There is only one wato find out for sure!! 73 Peter.
@@watersstanton Thanks, it's a difficult decision to make, everyone I have called back to on 20-10 has heard me. Had Russia on 40m which I think is better than expected for a half wave loop on 40m. I might give it a go in the future. 73's 2e0deq
Outstanding 73 stay safe 🙏
Thanks. Peter
Do you have to go from ladder line to coax? Can’t you just run the ladder line into the shack and hook it directly to the tuner? My tuner has connections specifically for ladder line.. thanks
Of course yiu can but not everybidy us comfortable with ladder line in the shack, particularly if they have no outside wall. 73 Peter,
@@watersstanton huh?
That’s great news, am in the process of putting my shack together, my new wife gave me a nice warm dry corner in the basement with an outside wall, I am going to run pvc conduit through the wall to run the ladder line
@@chadwickdavis1749 im confused. You say a basement wall, isn’t there going to be a lot of dirt on the other side? You going to run it up through 10ish feet of pipe to open ground?
A third of the basement is above ground so I just have to drill through the part that is above ground and install a short piece of pvc pipe through the wall and run the ladder line through it
what if I make a Doublet /dipol
fed with ladder line antenna on 80 meters tuned 3,600 MHz, will it then work on 160-10 meters ? LA2VLA
If around 40m element length, then may well do but depends on ATU capability. Am afraid it is a case of try and see. 73 Peter
@@watersstanton I'll try to see what happens but now it's too called out -5 and wind
Mmm Current Shoes. In seriousness: I'm not sure that you've shown that Doublets are different to Dipoles: Are Doublets not just a 'subset' of all possible dipoles? In effect, a 'better fed' dipole?
If I remember rightly, and I'm struggling to find a reference, but early radio pioneers thought monopole antennas were a completely different 'type' of antenna to dipoles, only to realise later they aren't, the ground plane effectively acts as the other side. (as opposed to things like slots, horns, etc which are very different beasts. - they are in effect again, a subclass of dipole antenna in the theory type world?
Thanks for sharing your views. 73 Peter
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Thanks Mark
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Thanks.