Hi Jim. Hope you are doing better. Always good to see you here and good luck on W5KUB!

Jim, you look 1500% better! Great lesson. I’m a picture guy. One picture with explanation is better than a bookshelf full of documents. Thanks for putting these presentations together.

It is incorrect or misleading to say an end fed does not need a counterpoise. It always needs a counterpoise of some type, the feed system always needs two terminals. This is one of Kirchhoff's Laws. Where people go wrong is not understanding the counterpoise and common mode current. The counterpoise can be quite small, a matter of hundreds or thousands of ohms in common-mode impedance. Even a 12-inch square can be an effective counterpoise on 30 meters for an end-fed thin half-wave wire. The problem is a small or no counterpoise creates a counterpoise voltage problem. If a counterpoise is small the impedance is high. A small or high impedance counterpoise pumps up in voltage to very high voltages. A small counterpoise has to do this to drive the end of the antenna with the current and voltage the antenna needs. The antenna's end impedance is high but is finite and dependent on antenna height, cross section (surge impedance), and the antenna surroundings. The feed impedance of an end-fed half wave ranges from hundreds of ohms for a very thick radiator like a tower or tubing to many thousands of ohms for a physically long half wave with thin wire high above the earth. But that end impedance is never infinite, so the antenna always requires a counterpoise of some form. We are often blind to the various forms a counterpoise can take, so we develop a false idea "this works fine without a counterpoise". The counterpoise can be very small under the right conditions. Most of the time the counterpoise is the feedline, and the feedline radiates! At times a feedline can radiate more than the antenna radiates! This can also be proven. A high impedance counterpoise will elevate itself to the surrounding world in voltage until it satisfies Kirchhoff's Laws and the same current flows into and out of the counterpoise terminal as the actual antenna. This current causes an elevated voltage from the counterpoise to the world around the counterpoise. That voltage is what causes the longitudinal voltage that drives unwanted common mode on the feeder, a tower, or a mast that is coupled to the feeder. It is actually possible to have, and it can be shown we can have, more current downstream in a counterpoise (intentional or not) because of surge impedances and standing waves. It is a crying shame we insist that no counterpoise is required. The lack of counterpoise is the root cause of common mode and efficiency problems. We falsely and repeatedly claim through some magic we can transition from our two or more conductor terminal circuit world to a single terminal radiator without handling that second terminal. This is a major educational problem we should work on. Instead, some end-fed half-wave antenna experimenters and educators wrongly tell others a counterpoise is not necessary or required. This misinforms people trying to understand the system and how to make the system work as well as reasonably possible. 73 Tom W8JI

@sprucebog217

6 ай бұрын

Thankyou. Magic is the word he used in the other video.

@timlee97

6 ай бұрын

Agreed…. An EFHW does not need an EXTERNAL counterpoise because it typically uses the outer conductor of the coax as it’s counterpoise. I’ve now deployed over a dozen EFHWs across a variety of locations and have noticed both tuning and performance varies depending on how the coax is run, along with the positioning of any chokes to reduce RF coming back into the shack. Namely, if I position any form of Common Mode Current filtering any closer to the EFHW’s feedpoint than .01 wavelength distance on the lowest frequency desired, SWR climbs and performance declines. I also have experimented with external counterpoises such as additional radials, a grounding system, along with the 80’x80’ bonded metal roof at my present QTH. What I found was zero benefit to an external counterpoise, over simply allowing the coax to provide the counterpoise function. If I isolated the coax AT the feedpoint of the 49:1 transformer using a CMC filter, external counterpoises would work, but I never found one that worked any better than using the coax (by moving the CMC filter away from the transformer by at least 14’). Just for some background, I used nothing but centerfed dipoles for decades and was pleased with their performance (I used them as “my standard of comparison” when experimenting with other antennas/designs). However a few years ago I had a deployment requirement that was no longer going to be conducive to centerfeds, so I tried an EFHW (in a location where I still had a centerfed to use as a comparison). I was somewhat surprised that the on air performance of the EFHW, in a full 80-90% of the cases, equaled the centerfed, even though the center of the centerfed was at least 10’ higher than the EFHW. In the very few cases where the centerfed had an edge, it was almost always by less than an S-unit, and only on the higher frequencies such as 15-10meters. On some bands (notably the lower frequencies) the performance was not noticeable, at all. My .02, FWIW, YMMV, 73 Tim W5TRL

Nicely explained and nicely presented, Jim. There are damned too few of you "REAL" Elmers in the hobby today. Like you, I try to teach, but oh, so many want to enter the hobby with a 1960's "CB Pirate" mindset. God bless you, Brother!

I'm used to feeing OCF antennas with a 50:200 ohm balun. At approximately the 1/3rd point along the 1/4 wave antenna, the impedance at that point for multiple bands is right about 200 ohms. The math just works out and they are pretty amazing antennas and not too bad for homebrew so long as you're able to raise/drop/cut/tweak many times till you're happy with it.

hi jim my name is Keiran im from australia and i just want to thank you for your videos they have helped me keep interested in the hobby as i studied for my foundation level .. i am now licenced and thats thanks in part to fellas like your self, guys and gals taking time to share their knowledge and love for this great hobby.. thank you and 73.. VK4QRM

Very nice presentation Jim. Good to see and hear you.

Fantastic production as always, Thank-you Jim🙏✌️

Always informative and understandable. Thanks for taking the time to share your knowledge!

Love your content Jim. Best wishes, Merry Christmas! 73

I must say Jim that you are looking well, hale and hearty. Thanks for the quick tutorial on antennas, I think I always knew what you are saying but I now have a clear visual explanation about antenna propagation. Wonderful animations.

Short but complete explanation. Thank You. God bless You. Stay in good health.

Thanks Jim. A great video for new hams trying to figure out which antenna configuration would be the best for their situation. Great to see you back sharing your knowledge and experiences. I hope that you are feeling well and you and your family have a Merry Christmas and a great 2024. I have being using a Buckmaster OCF dipole in an inverted vee (the peak is about 45') to fit my city lot for several years. Quite and many great QSO'S and DX contacts. I have used an EFHW with much success too. KC8WVG

I always like watching your videos when i have time 😊

Great visual representation! It might seem simple, but it took me a while to wrap my brain around the relationshop between the voltage, radiation and current, so this is a great learning aid!

Great animation. Thank you for the explanation!

Hi Jim, hope you are doing well man. Love watching your videos. Great information.

I could not explain this out any better than you did it, Elmer Jim. I love playing with these Wire Antennas all kinds of them. The Classic Dipole, Doublet Antennas, G5RV / ZS6BMW and of course my beloved EFHW Antennas. I mostly use the 49:1 System but do love to work the 9:1UNUN as well. Thank you Jim for another great Video. Merry Christmas to and the Family and a prosperous 2024 and keep well. 73 de Your Friend Uncle Günter from southwest Germany 💯🙏🍀♥🛡🙋‍♂

Good video, I like the animation. I use an EFHW at my QTH and have worked all over the world with it on ssb. Some people are naysayers about this antenna, but I have the confirmations to prove them otherwise. They work great if you can get them up nice and high good for DX. and there’s a reason why they’ve grown in popularity..I recommend grounding the outer shield before it enters the shack. Keep any RF out. Great for POTA! 73

Looking good Jim! Cheers

Thank you Jim. The clearest and frankly the most understandable that I've ever seen. Keep at it OM, 73-AA7MO

Looking good Jim, good video too.

Great description. Have been using an EFHW for POTA and getting good results. Take care andy N6JTX Orangevale, CA

Thanks 😊 I am in an apartment, top 4th floor, on a hill, and facing the woods too at over 300 feet asl. My HF antenna is a Windcamp WA4, Off Center Feed Dipole with a balanced. It is 60 feet on the long end, and 20 feet on the short end. From my terrace, I put the 60 foot length to the woods, and the 20 foot length on the terrace railing. I have a Yaesu FT-891 with a Yaesu FC- 50 tuner through an MFJ Antenna Tuner Extender accessory to the coax cable. 73 de W2CH Ray New Hampshire😊

Great video Jim. I just built 2 end fed long wire antennas in the past couple of months - one 72' and one 41'. The 72', I used the coax as the radiating counterpoise. The 41' has a 16' wire counterpoise because my coax length wasn't really long enough for that purpose. Yes it's basically a OCFD. If I am reading your animations correctly, they all have maximum radiation from the center. In my view, they all are basically the same in terms of how they radiate. I think we tend to over-complicate things. The goal of an antenna is to get maximum energy to the radiating wire. The different configurations are just different ways of accomplishing that at the end of the day. Performance will be around the same assuming all of them are straight and going in the same direction and are at the same height. Installing the antennas is where the variables get introduced (height, direction and configuration). Even a vertical is just a dipole turned 90 degrees. That is why a lot of guys can't picture why it needs radials or counterpoise. It's the other half of the antenna. Thanks again for doing these. de Scott, W1AL

Thank you Jim. The sharing of your wisdom is appreciated. De AI5RR

Another Great Video! My G5RV is the bread winner for sure on HF!

How are you doing, Jim! :-) You've made it clear! HW antenna stays being the HW antenna regardless of coax connection point. All one needs is just to match impedances. TU 73.

Nice animation. It's been my opinion that a simple center (or near center) fed fan dipole is probably the best first antenna, real estate permitting. New hams are spoiled by the internal tuners in today's rigs, and are missing out on valuable experience tuning antennas.

Hi Jim. Thanks for this video. I keep hearing all types of antennas are a compromise. Could you follow up with a brief set of pros and cons for each type of half wave antennas. Which has less noise, better receive, better transmission for example. Thanks again for all the great videos and vast experience you have.

Good information to pass on.

Thank you!

Good info. Just to be clear, all the antennas portrayed are "dipoles" by IEEE definition... regardless of where or how it's fed.

Well done!

Nice video on antenna overview 😊😊

I love EFHW antennas. I have mine set as a vertical in my big oak tree. Worked lots of DX with that bit of wire and 100 watts. Bouvet was the best so far but it seems if the other station can be heard, I can get through with persistence. Great antenna if you can only have one.

Thanks Jim

Hi Jim. You look better, hope you are feeling better too. 73 de SV1SLB, sending you Season's Greetings.

Good timing on the video. Was just going over cutting a wire to length for an off-center-fed. I'm thinking about trying 1/2 30 meter for the hot side and 1/4 40 meter for the cold side and seeing how that works. Thanks and 73 good sir.

@WR3ND

6 ай бұрын

Well, it radiates at 30 and 80 (10 and 4 MHz), but not 40... 🤔

@WR3ND

6 ай бұрын

I ended up trimming the counter lead so that the total length of both together is 1/2 40 meter wavelength, and the main lead is 1/2 30 meter wavelength. I'm working on setting up a balun for it still, but so far it seems promising.

Thank you Jim. It would be interesting to hear you describe what happens to those three in harmonic frequencies off from the resonant frequency.

Best wishes jim Merry xmas

Hi Jim, Nice visuals for the animation. Most hams use a 49:1 balun with a EFHW antenna. I had always thought the impedance was about 3K, but you mention upwards to 5K. There is also mention that a counterpoise of .05 - .07 wavelength may help. Hope to see you later tonight on W5KUB. Stay safe. 73 WJ3U

@AlexejSvirid

6 ай бұрын

Counterpoise turns end fed dipole into an off center fed dipole. It reduces impedance from 5k to 2k5 which makes 49:1 balun fit.

Thanks!! I missed your emphasis on the lack of differences in the three animations (in terms of current and voltage distributions). Am I allowed to use V/I to get an intuitive understanding of why off-center and end-fed have high R? (both have smaller or much smaller I at the feed points, so the denominator is small and the fraction is very large.

Hi Jim, thanks for this educative vid! Is it a mistake that the words “high voltage are drawn in red and the high value shape at the tips of the antenna is in blue? And vice versa the word Current is in blue but the shape showing swelling in the middle of the antenna (while weak at the tips) is in red? Are those both waves (perpendicular) form the radiating power of the antenna or just one of them? As far as I know there can’t be “voltage” there where there are no wires, but maybe some “field”?

HI Jim, Good to see you, thank you for sharing your knowledge, how are you going? any improvement? At the moment I am experimenting with 3/4 vertical antennas and despite the name " sky warmer " and other bad reputation it looks to work great for DX. When compared to a 1/2 wave it seems to be doing better, even if the mouthing is low to the ground, as you know matching a 3/4 antenna is fairly easy, and the wide band those antennas deliver helps cover most bands at low swr. Any thought about those antennas? As you know I keep going against the trends with my antennas all while keeping the power at 100watts or less (and yes, we did have a few QSOs before) Kind regards, vk4BYE Joe, and Marie-Ann VK4DJZ

Jim , when are you going to pull that protective cover off that Ftdx-101d 😂

Hi Jim, another great video! One question, and a reference to another source to review works too, why don’t you need radials or counterpoise for an efhw antenna? Thanks and good to see you.

@bobr6555

6 ай бұрын

Same reason you don't need radials or a counterpoise for a centre-fed half wave dipole - because it is a half-wavelength long. If you have a quarter-wavelength say as a vertical, then you need to use something to make up the missing quarter-wave, such as radials or counterpoise/s.

@joelaut12

6 ай бұрын

@@bobr6555 Thanks Bob! Appreciate the answer.

I want to get away from using an external tuner. I have the ocfd but want to build the ZS6 BKW antenna. Better than the G5RV supposedly. Thanks for the videos

Hi mate, I was wondering if you could show us if you have more than half wide length antenna wire.

Hi Jim your looking amazingly well. M7WLG here I chosen my callsign after you sir. Love my call sign. Hope to make contact with you 1 day on the air .

Doesn't common mode current have to flow on the feed line for the EFHW to work?

Can you do a video on stacking yagis

As antennas are tuned RC (ZC) circuits, and as each pole of an offcentre-fed antenna would have different resonance characteristics, if the feed point is offset from the end, then surely the resonant frequency would not be the same as for a regular centre-fed dipole, and the radiation pattern would also be very different due to the voltage and current patterns on each pole being different, and interacting with each other, and that interference pattern would create a much more complex radiation pattern as the magnetic waves are affected by the interference. Am I wrong? If yes, why?

What happens if you feed these antennas with ladder line or window line instead of coax. I’m experimenting with that now in my restricted space. Love the EFHWs though. 73 N9FGP.

Jim, I'm new to this, I have a 125 ft dipole and only 100-foot lot, so 25 feet runs down the tree, will this antenna work ok? Thanks Tom

Why don't we build Yagis with End-feds as the driven element, then?

How do you put your coax to a in fed antenna?

Please can you help me, Jim.I'm building ocf for 7mhz, should shortleg, or long leg go to coax, centre, I'm using short coax feed, information seems to suggest 4to1 balun? Brian m6baq (Dover UK)

👏👏👏

what kind of current / voltage are we talking about?

how can you calculate wether or not an antenna is complete?

So if EFHW's dont need a counter poise, why does my ECOM II Chameleon come with one? And why is it the antenna doesnt work when i disconnect it?

So if your in a giant field and could hang any one of these up, which who it be?