Creating a Folded Inverted-Vee Antenna (031) 

As always, a magister class, Ralph! Thanks a lot, 73. Pancho, LU4DCW

Backing into the length formula to derive the Velocity Factor for your particular wire and configuration is the CORRECT way to achieve accurate adjustments. I’ve seen other RU-vidr antenna makers explain their method which uses the standard factor, and as one might expect, their adjustments never prove to be correct, and in the end, they have to achieve their results by trial and error, which defeats using a formulaic approach in the first place. Kudos for actually educating the community. I really enjoy all of your videos. Edit: I just remembered, Callum (DX Commander) pointed out that a folded end does not react linearly to changes in length. Im guessing there is an exponential/logarithmic relationship involved. Trial and error may just be the most convenient method after all.

Just discovered your channel. As a Tech, I am impressed by your delivery, knowledge and professionalism in your videos. Thank you for teaching us the way you do, making it easier to follow the info. You have a new follower.👍 73

I love your passion for the artform. Keep up the great work.

I made a folded dipole for 40m last year. I made it out of a length of 450R window line. As the feedpoint impedance is close to 300R, I fed it with 300R ladder line down to the balun near the ground, used a 6:1 balun then coax to the shack. It worked really well, good and quiet too. I’d imagine yours is wider bandwidth than mine though, as the elements are spaced more.

I've played with many dipoles and I finally ended up with a 102' dipole, fed with 450 window-line, on a 48' tower and never looked back. It has not only able to hit all the HF bands (except 160m and needed because only have TH-7DX) but I get the best signal reports I've ever gotten. All of my old antennas were coax-fed, some even with baluns but after using balanced feeders I will never go back to coax again! In addition, we replaced the coax on a FD 40m delta-loop and dramatically increased its performance. 73...

You could construct a 3/8 folded inverted Vee antenna with a 9:1 balun and a tuning capacitor at the feed point. This antenna works excellently on multiple frequency bands.

Interesting and really well done! When trimming an antenna to its res freq, my trick is to work out what percentage of the desired freq the actual res freq is; If the res freq is too low then the antenna is too long by that percentage. So cut that percentage off the legs!

Well explained Ralph and a nice design. As you no doubt know, one feature of a folded dipole and other loop style antennas is the inherent DC 'grounding' meaning there is no static build up on the antenna. Such static build up has been known to kill VNA's if the user fails to short the center and braid of the feedline before connecting the instrument. Folded dipole are reputedly 'quieter' than a conventional dipole for this same reason.

Good stuff, I appreciate the time you put in to put in this video together, for 75/80 M I run inverted L here I have two elevated radials underneath my inverted L antenna inverted L is a single wire I have a toggle switch a double pole double throw toggle switch which toggles between two different sets of radials for one cut for 3790 the other one's cut for 3950 on the high end of 80 m it's a little bit of a trick to walk outside with my 10-ft pole I can throw that toggle switch right at the feed point of the antenna as the elevated wires are up 10 ft in the air but I can easily switch between 3950 and 3790 with a very low 1. 5 or less one to one SWR and I can move all over those two bands so I get the right chew and on the high side and the dxn down on the DX window but yeah I love antennas thank you...

So you can't extend your tether points into your neighbor's yard another possibility might be to use some inexpensive telescopic fiberglass poles to push up the end of the wire as high as you can get it maybe 10 ft or 15 ft high effectively creating a second angle on the descent that might be a way to improve your SWR even further

Fascinating, what about a small coil with taps at both ends to facilitate easy tuning, or center frequency shift later if you want to shift down towards the CW section? Presumably it would make it a little more compact.

Just a dumb question.? But when you hose clamp coax with out a rubber insulation between the clamp and coax , wouldn't that cause the swr to rise a little bit. Cause I know that when I move my coax around near metal the swr changes a little. And also dumb questio#2 in one of your pictures it looked like the coax was like knotted going through the eye lids. Would that not also cause the swr to rise. Now as for question 1 I may have seen the picture wrong you may not have the coax held down by hose clamps. To me that may seem like it would change the inductance characteristics of the coax. Iam no rf engineer , just mostly a cb radio hobbies. And iam a ham also. But just some things I noticed. I have used sewer pipe clamps with rubber insulation from home depot to put up antennas . Agin I do not know much about engeering antennas. Iam really just a hobbies. And I know that when coax Is looped or tightly knotted it changes the wire resistance inside. Cause it causes the center wire inside to flatten out, changing the resistance and velocity factor. To making it higher witch in turn changes the swr. Agin iam no expert just a cb radio hobbiest. May be straighten out the coax at the eyelids and see if the vswr and swr comes down. Agin like I said iam no expert. I learn from trial and error, cause I know that in electronics everything affects everything.

First of all a very good video well presented well done mate and keep doing such. Now the hard part and that is another stupid question or sound like that to you. Since the inverted folded vee antenna after trim has achieve that low swr and considering the transceivers you use are 50 ohms, why you need a balun at the top. Is this a real balun or is just a simple feeder. Thanks in advance for your answer and wish all the best to your projects. Dimi.

12 gauge wire radius is 0.0034' (0.0042 is 10 gauge)

Whats you call sign

You're making the assumption that all users are amateur extra license holders (us) and would use the entire band. General far outweigh amateur extra and techs outwiegh all.

terminate it in the middle and cover all the bands