A Folded Dipole for 2-meters (70-cm?) (048)

[@migalito1955]

I have not watched the video yet but folded dipole caught my eye. I used to build 3 or 4 element Yagis for 2, 6, & 10 meters and learned that having a compact or short boom thru a close spacing resulted in a low impedance which could be brought up to 50 or close to 50 ohms by using a folded dipole with the right seperation between wires. I ended up with some very good compact Yagis. Since I am not a big fan of DXing and use my antennas for other things such as conversations within 500 miles or radio astronomy many of my antennas are NVIS or at the very least have a high take off angle by being low to the ground. Once again I offset the lower impedance by being low to the ground with a folded dipole configuration. I found normal audio speaker wire often does the trick. After watching your video I see we essentially did the same thing in reverse. You needed the balun to bring SWR down & I needed folded dipole to bring SWR up. Incidentally, I'd probably not care about fancy looking and used squared off ends using normal 1/2 inch water pipe and right angle fittings or elbows. What you get in return for looks less cool is an even greater spread with good SWR due to the increased skin & likely easier to construct.

[@eie_for_you]

Yes, it is amazing how many and varied ways one can find to make functional antennas! 🙂

[@kf5hcr176]

Well done Sir. Thank you for your time. Thanks for being so helpful with viewer's questions. You're a blessing, I appreciate John 3:16, AMEN. 73

[@eie_for_you]

Thank you and you are very welcome! That's all what this channel is all about. 🙂 Jesus is the reason I am here! 😁

[@dennisqwertyuiop]

when you were bending copper wire, I was thinking I hav many size copper tubing in shop, Then you started on tubing,,,,,great video, as always

[@eie_for_you]

Thanks, man!

[@1shARyn3]

Suggestions for bending: (less desirable) -- fill tube with water and chill to hard mushiness (not solid ice). Bend around form and let "ice" melt. Then evacuate (much better, but messier) -- fill tube with white beach sand (dry and clean). Bend around form and evacuate sand from tube ....

[@eie_for_you]

I've heard of the sand one. I was *almost* tempted to try it myself. Never heard of the water method. Thanks for the input! 🙂

[@johnbarber7157]

Use fine sand and close ends, crimp, cut off excess, use pipe cutter only

[@Bazzawombat]

The working out the band radius and your tips brilliant. Nylon cutting board will eventually disintegrate under sunlight, as has happened to mine in the past. Thanks for posting, Barry, vk2fp/ag7vc

[@eie_for_you]

Thanks! Copy on the cutting board. I did an experiment with some. I took one raw piece and another I painted with a black "Krylon Fusion for Plastic" paint. I left them both out in the weather/sun. It was amazing the difference between the two. The second weathered *MUCH* better than the first. 🙂

[@David-hm9ic]

@@eie_for_you Marine stores and, of course, Amazon carry a product called "King Starboard" that is HDPE as are cutting boards. Starboard is UV stabilized and resists water much better than standard HDPE. Thanks for this video. I'm a new HAM and have learned very quickly the inadequacy of the standard handheld antenna.

[@stevegage5786]

n up the wire that you are using - fasten one end in a vice and insert the other in a speed controlled drill after a while of spinning the wire will so hard that it will be self supporting I use this method often for varies uses and it works very well

[@eie_for_you]

That is an interesting thought. Never heard that before. 🙂

[@MakeDoAndMend1]

Hi there. It's G1bki in the UK. Nickname is George. For info I have used many years ago car brake pipe. Low Cost and strong. Also as its hollow I have inserted garden wire at each end as it can slide in and out for tuning swr etc. Also used on a circular aerial. Cheers from old George

[@eie_for_you]

Thanks for the idea! 🙂

[@clarebaerr2699]

Well done < and having worked for MTS in M.B.you mentioned Moose lake , My father-in-law worked for Mts in The Pas William or Bill Forester You may have known him

[@eie_for_you]

Thanks so much! Small world!! Sorry, I do not remember Bill Forester. We lived in Moose Lake from 1992 to 2000. 🙂

[@johnhess351]

So the only way to adjust the antenna for desired resonant frequency is to rebuild the antenna?

[@eie_for_you]

You could purposely make it a *little* larger and trim the ends at the feedpoint to resonance. This would yield a larger gap between the feedpoint ends, but would prevent you from rebuilding it. 🙂

[@tedblack285]

Ok, you wanted a question. How would you go about doing this using Faraday Fabric Tape 1inch x 50 Feet Double Conductive Cloth Tape with Acrylic Adhesive, for Electrical Connection, like the j pole faraday? could it be done????

[@eie_for_you]

Good question and an interesting experiment! I cannot say for certain whether it would or would not work. Give it a try! 🙂

[@ninotortosa5637]

Hi, can we ground the folded dipole as driven element to the antenna boom for a yagi array

[@eie_for_you]

I believe it can, though I've never tried it or simulated it. Each element's resonant frequency would have to conform the the same rules that would be used for a straight dipole configuration. You could give it a shot, simulating is with 4NEC2 (FREE antenna modeling software). :-)

[@thed8229]

Very cool. I've been sharing your channel & vids with some of my other club members. I'm learning every time I watch one. K0ATV

[@eie_for_you]

I am so glad that I am making a difference. This is my sole purpose here. Thank you for the encouragement! :-)🤓

[@pawank.patidar]

I make 137 cm. Dipole for 100mhz fm 300 ohm impedance. For convert 75ohm coaxial balun wire lenth = ?cm. Please guide me.

[@eie_for_you]

Well...the quickest and most complete way to help you here is to point you to my video on how to make that 4:1 BALUN that you need using just some coax. You will find that video here: kzbin.info/www/bejne/nHiai6Opn72FjZo This video will walk you through step-by-step how to make one and why they work. Hope this helps.

[@kd5txo]

Since this antenna is already 300 Ohm and balanced at the feedpoint, why not use 300 Ohm twinlead as the feedline? The feedline will be far less lossy than any Coax you could buy. Then you could put the balun at the radio end (Indoors and dry) and reap the benefits. Plus, you will have the opportunity to tinker with the balun for even a better match into the antenna.

[@eie_for_you]

Your idea does carry some merit for installation situations which would allow it. For those folks who can do this and want to do it, go for it! It is a reasonably decent idea. It just occurred to me ... with a 4:1 BALUN and an SWR of nearly 1:1, given that this is an inverted vee and not a dipole, the actual impedance of the antenna here is probably closer to 200 Ohms. The impedance is adjusted, in part, by changing the angle between the legs. This I did to bring my SWR down a bit. Thus, twin lead at 300 Ohms ... not necessarily a good match. Without going into my installation situation, the convenience of coax far outweighs the benefit of twin lead here. 🙂

[@PatAutrey]

what improvement in gain do you get with this folded dipole as compared to a regular dipole?

[@eie_for_you]

Ya know, I am not sure. I'd have to run the simulations of the two to discover the answer to this question.

[@PatAutrey]

@@eie_for_you I have a request for a video. VNA and Smith charts will tell us what we need to do to match an antenna system to a radio, however no one has ever made a video of actually showing that matching and practice. For instance if it says to put a 470 picofarad capacitor and a 50 micro Henry inductor to match the antenna how do you do that how do you add these components to an incentive system what is the proper way to do it what is the best way to do it I am clueless and I have not seen any videos of anyone else ever showing how to do it either Would really be appreciated if you could show how to add The recommended components to an antenna system so that it will match it according to the VNA or according to the Smith chart

[@eie_for_you]

@@PatAutrey Hmmmm, an interesting thought. I will add this thought in my list of potential videos to create. Thank you for the suggestion! 🙂 Here is a quick answer to the question for your benefit. If you used the VNA to measure the impedance at a particular spot and used this impedance to determine the required matching network components, then this matching network would have to be applied at the same spot that you measured the impedance at. Alternatively, you could do the same if you were another 1/2 wavelength (electrically speaking) away from that point along your feedline because the impedance reoccurs at 1/2 wavelength intervals. I hope this quicky answer helps.

[@PatAutrey]

@@eie_for_you thanks for the quick reply I understand the idea of using a half wave coax so that it remains the same but where I'm confused is what do you use if it asks for a capacitance do you just get a capacitor or do you get a coax that acts like a capacitor I've just never added any tuning components to a system before and I'm unfamiliar with the process of how you physically do it

[@eie_for_you]

@@PatAutrey Another quick answer would be that doesn't matter if it a piece of coax that looks like a capacitor or a real, physical capacitor component, as long as it "looks like" a capacitor. Here is an example in creating a stub match to make that folded dipole match to a 50 Ohm coax. kzbin.info/www/bejne/goqXeKyprbh4l5I

[@JeffSmythe-f7e]

For SSB the dipole has to be horizontal and i don't understand the the dimension i just need inches.

[@eie_for_you]

I give the dimensions in both english (imperial) and metric. You will find them all there. If you open the antenna modeling file, you will find them all in feet. I use this antenna for SSB all the time and get way awesome signal reports. Hope this helps. 🙂

[@johnhess351]

I never heard you say what advantage the folded dipole has for 2 meters over any other similar antenna. I thought the main advantage to the folded dipole was running long lengths of ladder line, which you are not doing.

[@eie_for_you]

A folded dipole has a wider bandwidth than a normal dipole. This is the main advantage. With a properly assembled folded dipole matched to a properly tuned 4:1 BALUN (like I show in this video: kzbin.info/www/bejne/nHiai6Opn72FjZo), you can have a very nice, flat SWR across the entire 2M band. 🙂

[@johnhess351]

@@eie_for_you thank you

[@rtybn2012]

I would make a dipole antenna not folded. Dipole is easier to work with and is a 50 ohm antenna. A L C match can be constructed very easy using a table which can be found in a ARRL handbook.

[@eie_for_you]

Yup, dipoles are easier. I honestly haven't built one for VHF, so I do not know how well they would cover the whole 2M band. The advantage of the folded dipole is bandwidth. I built an 80M folded inverted vee and it nearly covers the entire band within reach of my antenna tuner. It's plain old inverted vee predecessor didn't even come close. Enjoy! :-)

[@dougtaylor7724]

If you put 4 of these together in a row, how to figure out the spacing?

[@eie_for_you]

Great question and no easy answer because it depends on what you are trying to do with them. This involves two aspects: (1) the physical spacing (2) the phasing which is accomplished by the impedance, length and velocity factor of the cable harness that connects them to each other and to the feedline. You can play with all of this in 4NEC2, antenna modeling program (FREE). I have played with a phased array (mine was four square as opposed to stacked) inside 4NEC2, but I've never actually built any of this stuff. :-( Sorry I couldn't be of more help, but thanks for the comment and question! :-)

[@tedmead465]

Stacked array would be 1/2 wavelength apart for optimum eficiency. If for a yagi beam look up a yagi calculator.

[@stevegage5786]

the other comment got messed up it was meant to read To stiffen up the wire you are using ..........

[@eie_for_you]

Yup...I figured that out. Thanks for the clarification, though. 🙂

[@rhondafox7131]

To get a 1 to 1 standing wave.

[@eie_for_you]

Gotcha. 🙂

[@rhondafox7131]

You need a feed point impedance of 200 OHMS for a 4:1 balun called a beta match.

[@eie_for_you]

And that is exactly what I applied to this antenna ... a 4:1 BALUN using coax. I have a detailed video on the how and why of such a coax-based 4:1 BALUN here: kzbin.info/www/bejne/nHiai6Opn72FjZo 🙂

[@ornithopterindia]

👍

[@stevegage5786]

thank you for your lectures --very help full --better than ask Dave ha ha zs1bbg

[@eie_for_you]

You are welcome!

[@xszl]

Ok, so..eh, but 70cm band is 430-440 MHz here..swr is no good.

[@eie_for_you]

Here in the states our 70cm band is from 420-450 MHz with a whole bunch of repeater frequencies huddled at the top end of the band. It is at the high end of the U.S. 70cm band where the version of the antenna that I built has an adequately low SWR to be useful. Below that, you are right...SWR climbs rather quickly. 🙂

[@walkingnorth4474]

To bend soft copper tubing, get the lenght that you need plus some ( put the end of copper tubing in a vice and squeeze end shut fill the copper tubing with silica sand and do same with other end ) you can now bend it around any diameter do not have to buy different jigs MaverickIA walking north@walkingnorth4474

[@eie_for_you]

Yeah, I've heard that (too late before I spent the $$ on the tool). Sounds like a pretty slick way of doing it. Plus it means unlimited angles ... I could make a helix if I wanted to! 🙂

[@walkingnorth4474]

@@eie_for_you Do you help with questions about ham radios

[@eie_for_you]

@@walkingnorth4474 I am a ham and, yes, I do answer questions about ham radios ... depending on the question. Try me. 🤓

[@walkingnorth4474]

@@eie_for_you I have a 10 Tech Delta 2 model 536 I replace the coin size battery for the clock Now it seems like that I cannot add frequencies to memory I enter one frequency and save it and then add another I will not keep the first one I do have the manual and schematics Appreciate your help

[@eie_for_you]

@@walkingnorth4474 First, I am assuming that the reason why you replaced the coin cell is because you were having issues with the radio remembering things. A LOT of these radios have solder-in coin cells 😳. This always puzzled me cuz they gotta know that they are going to need to be replaced! Here would be exactly what I would do: If this is a solder-in device, I would do 4 things, fixing as I go: 1. I would use a voltmeter to check the voltage on the battery (it could have been damaged / overheated in the process of soldering it in). 2. I would verify that the new battery was soldered in with the right polarity (*easy* to switch this up with some batteries) 3. I would carefully inspect the solder joints. Make sure they have flowed properly and making good connection. 4. I would very, very carefully inspect the traces leading to the battery pads to be sure that they haven't been cracked or broken. This can happen *very* easily especially when wrestling with unsoldering the the old battery. These cracks can be very, very small...use a magnifying glass. If it is a socketed battery, I'd first make sure the battery is in the holder in the right orientation and protective tapes taken off of it. Then I would do 3 and 4 from above. Hope this helps. 🙂