Lol, loved when you dropped the J-pole, showsneven a great presenter like you is human. Great explanation of an antenna I've been using for almost 30 years.
"And the current goes down" (antenna drops, startled look, instant resume, show must go on!). Thanks for the explanation, very concise and to the point!
Finally, the J-Pole is no longer a mystery! Thank you for this valuable information (as well as how to tune the dang thing). Looking forward to more like this! 73 KE8EAS
I listened to this right after I purchased a nice breakaway J-Pole, and just now. I've learned a lot since July/August and, now I could actually follow what you were saying. Thanks for all the great videos that you do! You really help us learn out here.
Total ham noob here. I'm trying to get my license in Canada. This video helped me so much! I learned what's the meaning of 1/2-1/4 wavelengths and this is the best video to understand how an antenna works. Very good job! 73
Hello, my call sign is W4LAG from Lee, Florida. I am new to Ham Radio and I have been searching the web to learn more about the hobby. Your videos on RUclips have opened my eyes and hunger to so much more. Thank you for taking the time to help us newbies.
I built several of these many years ago without understanding the concept of how they worked. Was always amazed at how good they performed with just a handheld hooked up.
Thank you very much for making this video! I just passed my Technician and General exams this past weekend and have been working hard to get a solid station set up while I wait for my callsign -- I plan on building a J-pole antenna this weekend and now I'll know what I'm doing! Great video, very high quality and very concise, thanks again! 73
Dave: 50 years a ham, and I'm still learning cool stuff. Thanks for revealing the mysteries that make this hobby so fascinating. I'm working on my j-pole now. It's my first, but it certainly won't be my last. Too much fun to build. 73 W0AP
I came across this video when I was looking to see if a J-Pole should be grounded. I've seen enough of your work, Dave, to have a lot of respect for your opinion. Grounded it is, and thanks to this video I see why. 73 de K1PXF
Thanks Dave. When it comes to electronic theory and practice I need it to be explained to me in simple terminology. I now understand what is happening with this antenna. I appreciate you explaining it for people like me.
I agree with D. Mckee, this was a wonderful description. I never really understood the "magic" of a J-pole, even though I used a couple of them in my early days. I had gotten your typical copper J-pole from a fellow ham in the local club I belong to. I made a sort of tripod for it, intending to have it free-standing on my 3rd floor balcony of my apartment. I even found spray paint that sprayed very thick, with a textured result like rough stone. It also had flecks of different colors, and when sprayed with this stuff, the J-pole blended into the brick of the building so well you literally could not see it from the ground. Perfect! Until I used it to transmit. Then the neighbor downstairs would take a hammer and pound on his ceiling (our floor) to let us know that we were interfering with his electronics. It would seem that our 2 meter signal was coming through on everything from his stereo to his clock radio. As this man slept days and worked nights, if I used 2 meters during the day, it would wake him up, when a garbled mess started yammering into the speaker on his clock radio on his nightstand. This would not do -- the guy could complain to the management and cause real problems! So I had to find an antenna that would still let me reach repeaters in the area AND no longer go through his consumer electronics. The answer was straightforward. A Moxon loop for 2 meters. I made a pair of them with hookup wire stretched on the ends of an "X" shape of dowel rods secured in the middle. The ends of the two elements had small turnbuckles to adjust the length, to allow them to be tuned, and short pieces of thin shock cord to hold them taut. I mounted each Moxon on a free-standing garden privacy fence section, 7 feet tall and 3 1/2 feet wide. It fit against the ends of our balcony very neatly, and I secured them to the railing with cable ties. The Moxon let me get into area repeaters perfectly, and the neighbor never complained again. I also operated HF from that apartment, using an MFJ random wire tuner for a while, but then upgrading to their tuner with artificial ground. I would fasten a fishing sinker to the end of a spool of magnet wire and shoot it into the woods across the parking lot below. Then the near end would go to the tuner. I worked stations as far as central Europe on that piece of magnet wire!
Thank you Dave. I finally got it. It's taken years, but I finally get it. Why didn't someone before you use masking tape and explain the balanced line ? I now get it, thanks :-)
Great explanation. When I was a kid, I couldn't figure out how a stub-match or gamma match didn't just short out the works. About 10 years ago, I built a 2M J-pole from copper pipe. Worked fantastically. Someone else still uses it. I'm ready to build another for myself.
If anyone wants to build one, very cheap and easy, might i suggest this: 1, calculate rough dimensions. Jpoles are pretty forgiving, as are easily tuned. You need to know your long length, your short length, n your gap. 2, find a peice of pipe (i used 12mm aluminium) a bit longer than those 3 added together. Mark your short length + 1/2 pipe diameter, n gap + 1/2 pipe diameter. Cut a 90 (45+45) degree notch at those marked spots. 3, bend at the notches to form your J. Cut 2 peice of pvc conduit (i used 16mm electric) 2x your gap measure. Using the base of your J as a template, drill holes for your short and long sides, with the shortside hole close to the edge, longside roughly middle, and a stub out the other. 4, slide your spacer close to the bottom, then an appropriate hose clamp on each element. The other spacer then goes on. Position around the top of the shorter element, so a strong box is made. In a larger peice of pvc, drill 2 holes to fit the stubs in. I used 24mm water pipe. This is your mount. Mine is fairly short, as it attached to a steel mast, but this could be your mast. 5, attach your coax to the hose clamps, and clamp to the approximate area shown by the calcs. Erect vertical and a halfwave in clear space. SWR. Adjust as needed. I got 1.1 on the second shot. My point is, although 90% of the J Poles seen on the net are soldered from plumbing fittings, a hacksaw and drill are all you need for a very effective, rugged antenna. Once tuned, i put a screw in all the joints, and when i got it home, tapped a hole where the coax feed was n secured the coax better. But that was after 6 months of operation at our vacation home. Everything was built from bits lying around, except the $5 ali piece of pipe. Took under an hour to build. As an added bonus pro-tip, busted up shade tents are a great source of push-up poles. One plastic knuckle breaks, n people chuck the whole lot out. Can very easily put up a 15m mast with a few old shade tents. Just guy them adequate, pretty floppy with all them joints. Ghetto 2m Jpole in a weekend, most expensive part was the ropes. Have fun!
Thanks !!! I finally get why the connection at the bottom is the way it is...it's the 50ohm matching point !!! I have three j-poles I have built and never really got that. I just made it the best SWR and didn't even think about the 50ohm matching point !... Great explanation. Now for my next one I build I will actually look for the 50 ohm point! That also explains why when I experimented with 75ohm coax the connect point was different !
Thank you for the very clear explanation. I am impressed. I could figure out the J-shape in the name, but didn't know how else it was supposed to work. Thank you!
Very good Dave. Very valuable information. We are forming a group of Emergency Communication Specialists here in Saskatchewan and this looks like the dream antenna that we are looking for.
That's a great explanation of how a J pole works, made simple, Dave. I made one yesterday before watching this. It's a super J pole made from 450 Ohm twin feeder. I don't buy aerials. It's still amazing even after 40+ years of my doing radio, what is a short at D.C. can be 50 Ohm at R.F. Bill, G4GHB.
Hi David, Can we have a "How does a SLIM JIM antenna work?" - we love your method of explanation and your rich knowledge. Highly Appreciated ! Keep up the great work !
Actually I see almost identical patterns but the slim jim has to go up higher than 10m (~30ft) to be more effective, check this article: www.hamradio.me/antennas/slimjim-vs-traditional-j-pole-antenna.html
What a great explanation. I always understood a J-pole was 1/2 wave but the lower section/ matching confused me. I had assumed maybe I was dealing with a 3/4 wave in reality, which will match 50 ohms. Thanks.
Thanks for the run down. I took notes. I am about to build my first j-pole and this gives me everything I need to know about how they work and what the impedance does. AD5IX
this was amazing. i mostly understood it in the function of visual RF/wave form, though the explanation of voltage/current/impedance really solidified it.
1:12 "this is what you connect the antenna with"... I think the word "mount" might have been better here, just a thought.. 🤔 I built a J pole years ago for my scanner and was delighted with the results ! Thanks for the vid, always worth watching and learning ! 😎👍☘🍺
Your style reminds me of those educational/instructional TV shows back in the 1990s like: The New Yankee Workshop and Bob Vila's Home Again. I like it! One thing i'd like to see you add to your show is, by haps, a "set" in the background. It could be your radio shack or even a workshop since you also show how things are made.
I should ask viewers to submit photos to use as a background. Right now I use a background that came with my editing software, which I modified to include the OG! logo.
Hey Dave, I built a copper J-pole antenna today. It's Rx is fantastic, but on Tx my swr was 20+. I was worried I needed to rework the feedpoint, but after watching your video I realized that to match a balanced "feedline" (the 1/4 wave parallel section) to my UNbalanced feedline (coax), I needed a balun. After wrapping one up and attaching it, I was down to 1.4:1 on my selected freq. I realized I can get that even lower still with some trimming, as a few MHz below that was getting 1.2:1. Thanks for the balun advice in there, it really helped me out! 73 KN6AZK
Would be great if you did an entire series on antenna designs and "how they work". I'm currently reading Joseph Carr's "Practical Antenna Handbook" and despite being extremely technical, learning a great deal about how antennas work. I would like to hear some of the material explained on your show!
Ahoy sir!. I'm just getting back into the radio hobby after 24 yrs. I'm more of a listen than talk guy( scanner/SW). I have always been both facinated and intimidated by antennas and theory. Your vid was interesting and very simple to grasp. Would like to learn more about it, and get my entry level amateur license. Good job sir 👍
Thanks for making this easy to understand! I am researching to get into the radio hobby something I have put off for the last two decades because of elitist and needing good amount of time to learn everything to get things right. This was a great video! I look forward to diving into your channel. Subscribed and up voted.
David, I'll join the chorus of kudos for such a wonderful explanation for what is such a mysterious device for many folks. (Hand raised) As you started with the dipole section, I visualized the current/voltage diagrams as seen in the old handbooks. Your explanation of the transmission line section tied it together. Not only did the proverbial light come on, but so many that we can now light up our Christmas tree, hi hi. Your video also indirectly explains why a mobile J-Pole would be impractical. There would be too much stuff (other cars, trucks, trees, curious people) that would interfere with the high impedance section. It also explains why it's best to have these high up in the air Thanks again! 73 de KA0RFB
Nice, clear explanation. I would add to be wary of grounding the bottom of the antenna, its supposed to be zero volts, but it never quite is, so you can get unpredictable things happening. Personally, I would keep the antenna insulated from a metallic mast.
Bravo! Thank you for an illuminating explanation! If I understand the matter correctly; At a DC voltage, it is a dead short, but at a VHF frequency, it is not shorted! I am not transmitting or receiving a DC signal so the dead short issue is moot! 73 Russell KE7QXR
Dave: One of the best educational RUclips videos I've seen; not only in the ham radio genre, but period. So I built a center loaded J-pole from some plans that is supposed to be dual band. Where does 70cm come in to the equation? Thanks again, Todd (AD0RR)
I knew most of those things separately, but you put it together beautifully in a way that makes sense! Thanks heaps for this video, you got yourself a new subscriber :D Cheers from down under!
Okay, this makes so much more sense now, I had always heard them described as a 3/4 wave antenna, now I get it, it's really a 1/2 wave with a rather strange feeder. In other words, if you removed the 1/2 wave section above the masking tape, although it would exibit a good VSWR, it would radiat very little to nothing, because, just like open twin lead transmission line, one side cancels out the other because they are 180 degrees out of phase and parallel to one another. But the most interesting thing about this video is, I have always been in a controversy over which side of this to feed, and I have always feed them on the long side, and with my ground shield on the short leg thinking that it was a ground poise for a 3/4 wavelength antenna. But instead the bottom portion, is infact an impedance matching transformer for a 1/2 wave diapole, which requires no ground plane at all, but it does require a balanced feed which is why I can never get a really good VSWR. it's the same as trying to feed a center fed dipole, or an inverted V without louping the coax or running it through a ferrite bead or two.
Just getting started in amateur radio, so I am like a sponge trying to learn this stuff. Great explanation on how it actually works. And how did I find this video? I am buying the Arrow Antenna J pole dual band for my 1st antenna. Small, functional and inexpensive (that's what the wife likes). Friend and I passed our tech test a month or so ago. Then he pass his General two weeks later. He's a Brainiac but I'm not. I have to learn it to understand it and not just learn questions and answers. You'll be seeing me a lot on here now. Thanks and 73's.
Happy New year Dave. Wow I have always wondered how one of these things work. That has to be the best video I have ever seen regarding a j pole. I guess it's the same for a slim Jim. Fantastic video. Motters M7TRS 73's
I wish I were smart enough to understand what this guy is taking about. I just passed my Technician exam last weekend. Maybe some day what he said will make sense to me.
At 6:25 you mention getting the J-pole way up in the air, above your head. Can you give a little more detail on that ... is it a certain distance from the ground that matters, or not being next to your body / head? I have a portable J-pole on a stand that starts about chest height, so I'm wondering if I should avoid standing near it, or if it needs to be further off the ground, or what.
thank you for a really brilliant video - i love your teaching style, you make it really interesting and engaging, plus your videos are always really polished/professional ! thanks again ! (subscribed)
Dave love your videos . I am DE KC5ULU . I ask you about the omni charistics of the j-pole antenna . Heard your reply today thank you for taking time. I wanted to let you know my test site is in my back yard , maybe not optimum but works . I have a MFJ analizet the old 259 model which to my surprise will transmit a signal , it isn't strong but enough to see it on my Sedelco 733 super band field strength meter . My meter is a Seldco antenna meter covering the low mid and hi band vhf I have 40' of rg 6 run across the yard from a simple dipole antenna 30' away it allows me to tweak the receive meter to the transmit signal of the mfj 259 at one location . By doing this I am able to see a relative signal in microvolts . Now I can compare other antennas to each other or see how much better of an improvement I can get without asking someone else for a radio check, which we both know is useless. My receive antenna is 10' off the ground the test antenna is also 10' of the ground and I sit under the transmit antenna to get all my comparative readings. This is how I saw problems with some antennas J pole was one . I could grab the coax too to see if I get a meter movement indicating a common mode current on the outside of the coax . Now I am aware this is far from optimum , I know I have interference from reflections all around but for a simple test it seam to offer a world of important information. One great feature is that, a 3 element horizontal omni antenna I have been working on was mounted to an aluminum mast , then tried a pvc mast with a wooden insert for stiffener and it showed an improvement of "300 micro volts". Thats a huge improvement. AS it is my ssb 2 meter weak signal can hear 300 miles without any enhancement in the way. I have a pair of these 3 element phased antennas stacked 5' apart . It is the best I can find out there in omni. I compared a standard J-pole to a super J , WOW ! What a difference , also tried an J-beam and that to showed a great improvement in forward and rear rejection .this 1/2 wave end fire antenna was a great invention.
![Noob To Max With DRAGON REWORK In Blox Fruits [FULL MOVIE]](http://i.ytimg.com/vi/LnBMOinoOvA/mqdefault.jpg)
One of the best, most straightforward, simplified explanations of a J-Pole I have ever come across. Well done and thanks.
Amazingly precise yet simple explanation of J-pole. From a Signal Integrity engineer. 73 KE8YVP Jason
Best explanation of a J-pole I've heard. Now I understand. Keep up the good work. 73.
I fully agree.
But who thought it up in the first place? ... A guy from Poland named Jay?
Absolutely, thanks for explaining it so this dummy can understand.
Lol, loved when you dropped the J-pole, showsneven a great presenter like you is human. Great explanation of an antenna I've been using for almost 30 years.
;-)
THANK YOU, Dave! You have unlocked one of the mysteries of the universe for me, and I learned lots more along the way. Please keep it up!
"And the current goes down" (antenna drops, startled look, instant resume, show must go on!). Thanks for the explanation, very concise and to the point!
not only was the video entertaining,I actually learnt something,well done.
Wow!!! I can't believe how easy to understand you made that. Subscribed!
Ditto !
Finally, the J-Pole is no longer a mystery! Thank you for this valuable information (as well as how to tune the dang thing). Looking forward to more like this! 73 KE8EAS
I listened to this right after I purchased a nice breakaway J-Pole, and just now. I've learned a lot since July/August and, now I could actually follow what you were saying. Thanks for all the great videos that you do! You really help us learn out here.
Ive watched a dozens videos and have yet to understanf jpole antennas until this one! I just want to thank you for your time and help!!!
Total ham noob here. I'm trying to get my license in Canada. This video helped me so much! I learned what's the meaning of 1/2-1/4 wavelengths and this is the best video to understand how an antenna works. Very good job! 73
Thank you.
Hello, my call sign is W4LAG from Lee, Florida. I am new to Ham Radio and I have been searching the web to learn more about the hobby. Your videos on RUclips have opened my eyes and hunger to so much more. Thank you for taking the time to help us newbies.
You're welcome!
I built several of these many years ago without understanding the concept of how they worked. Was always amazed at how good they performed with just a handheld hooked up.
Thank you very much for making this video!
I just passed my Technician and General exams this past weekend and have been working hard to get a solid station set up while I wait for my callsign -- I plan on building a J-pole antenna this weekend and now I'll know what I'm doing! Great video, very high quality and very concise, thanks again! 73
Terry, welcome to ham radio!
Best instructor ever...73s.
Dave: 50 years a ham, and I'm still learning cool stuff. Thanks for revealing the mysteries that make this hobby so fascinating. I'm working on my j-pole now. It's my first, but it certainly won't be my last. Too much fun to build. 73 W0AP
I came across this video when I was looking to see if a J-Pole should be grounded.
I've seen enough of your work, Dave, to have a lot of respect for your opinion. Grounded it is, and thanks to this video I see why.
73 de K1PXF
Thanks Dave. When it comes to electronic theory and practice I need it to be explained to me in simple terminology. I now understand what is happening with this antenna. I appreciate you explaining it for people like me.
I agree with D. Mckee, this was a wonderful description. I never really understood the "magic" of a J-pole, even though I used a couple of them in my early days.
I had gotten your typical copper J-pole from a fellow ham in the local club I belong to. I made a sort of tripod for it, intending to have it free-standing on my 3rd floor balcony of my apartment. I even found spray paint that sprayed very thick, with a textured result like rough stone. It also had flecks of different colors, and when sprayed with this stuff, the J-pole blended into the brick of the building so well you literally could not see it from the ground. Perfect!
Until I used it to transmit. Then the neighbor downstairs would take a hammer and pound on his ceiling (our floor) to let us know that we were interfering with his electronics. It would seem that our 2 meter signal was coming through on everything from his stereo to his clock radio. As this man slept days and worked nights, if I used 2 meters during the day, it would wake him up, when a garbled mess started yammering into the speaker on his clock radio on his nightstand. This would not do -- the guy could complain to the management and cause real problems! So I had to find an antenna that would still let me reach repeaters in the area AND no longer go through his consumer electronics.
The answer was straightforward. A Moxon loop for 2 meters. I made a pair of them with hookup wire stretched on the ends of an "X" shape of dowel rods secured in the middle. The ends of the two elements had small turnbuckles to adjust the length, to allow them to be tuned, and short pieces of thin shock cord to hold them taut. I mounted each Moxon on a free-standing garden privacy fence section, 7 feet tall and 3 1/2 feet wide. It fit against the ends of our balcony very neatly, and I secured them to the railing with cable ties. The Moxon let me get into area repeaters perfectly, and the neighbor never complained again.
I also operated HF from that apartment, using an MFJ random wire tuner for a while, but then upgrading to their tuner with artificial ground. I would fasten a fishing sinker to the end of a spool of magnet wire and shoot it into the woods across the parking lot below. Then the near end would go to the tuner. I worked stations as far as central Europe on that piece of magnet wire!
Thanks for the info!
Thank you Dave. I finally got it. It's taken years, but I finally get it.
Why didn't someone before you use masking tape and explain the balanced line ?
I now get it, thanks :-)
Watched this, then slept on it. Next day watched it again so I can now understand and explain it myself. Thank you Dave!
Great explanation. When I was a kid, I couldn't figure out how a stub-match or gamma match didn't just short out the works. About 10 years ago, I built a 2M J-pole from copper pipe. Worked fantastically. Someone else still uses it. I'm ready to build another for myself.
I just re-watched this excellent video! Best explanation I've ever seen for a J-Pole! Thanks Dave!
If anyone wants to build one, very cheap and easy, might i suggest this:
1, calculate rough dimensions. Jpoles are pretty forgiving, as are easily tuned. You need to know your long length, your short length, n your gap.
2, find a peice of pipe (i used 12mm aluminium) a bit longer than those 3 added together. Mark your short length + 1/2 pipe diameter, n gap + 1/2 pipe diameter. Cut a 90 (45+45) degree notch at those marked spots.
3, bend at the notches to form your J. Cut 2 peice of pvc conduit (i used 16mm electric) 2x your gap measure. Using the base of your J as a template, drill holes for your short and long sides, with the shortside hole close to the edge, longside roughly middle, and a stub out the other.
4, slide your spacer close to the bottom, then an appropriate hose clamp on each element. The other spacer then goes on. Position around the top of the shorter element, so a strong box is made. In a larger peice of pvc, drill 2 holes to fit the stubs in. I used 24mm water pipe. This is your mount. Mine is fairly short, as it attached to a steel mast, but this could be your mast.
5, attach your coax to the hose clamps, and clamp to the approximate area shown by the calcs. Erect vertical and a halfwave in clear space. SWR. Adjust as needed. I got 1.1 on the second shot.
My point is, although 90% of the J Poles seen on the net are soldered from plumbing fittings, a hacksaw and drill are all you need for a very effective, rugged antenna.
Once tuned, i put a screw in all the joints, and when i got it home, tapped a hole where the coax feed was n secured the coax better. But that was after 6 months of operation at our vacation home. Everything was built from bits lying around, except the $5 ali piece of pipe. Took under an hour to build.
As an added bonus pro-tip, busted up shade tents are a great source of push-up poles. One plastic knuckle breaks, n people chuck the whole lot out. Can very easily put up a 15m mast with a few old shade tents. Just guy them adequate, pretty floppy with all them joints.
Ghetto 2m Jpole in a weekend, most expensive part was the ropes.
Have fun!
Thanks !!! I finally get why the connection at the bottom is the way it is...it's the 50ohm matching point !!! I have three j-poles I have built and never really got that. I just made it the best SWR and didn't even think about the 50ohm matching point !... Great explanation. Now for my next one I build I will actually look for the 50 ohm point! That also explains why when I experimented with 75ohm coax the connect point was different !
Thank you for the very clear explanation. I am impressed. I could figure out the J-shape in the name, but didn't know how else it was supposed to work. Thank you!
By far the best explanation of impedance matching I've seen. Thanks 👍
Brilliant explanation! The light bulb just went on, thank you.
Brilliant description of J Pole - thanks, takes me back many years.
Very good Dave. Very valuable information. We are forming a group of Emergency Communication Specialists here in Saskatchewan and this looks like the dream antenna that we are looking for.
This man radiates kind old science teacher vibes and it's amazing
Wow! That was simple. Thanks for the neat concise explanation. Now I can build one AND simply explain how it works. 73 KB4ROR
That's a great explanation of how a J pole works, made simple, Dave. I made one yesterday before watching this. It's a super J pole made from 450 Ohm twin feeder. I don't buy aerials. It's still amazing even after 40+ years of my doing radio, what is a short at D.C. can be 50 Ohm at R.F.
Bill, G4GHB.
This is a really good full explanation of J-pole antenna build, thankyou.
As others have said, superb explanation of how a j-pole works, certainly one of the best.
Wow. What a fantastic explanation. This is great, I always loved the aesthetics of the design, but had no idea how it actually works.
Awesome video. I've been building and using J-Poles for years because of their simplicity. But I never really understood how they work. Now I do.
Thanks!
It's very pleasant to listen to Dave. I'm still a big n00b in antenna's but I'm getting it a little bit.
Hi David, Can we have a "How does a SLIM JIM antenna work?" - we love your method of explanation and your rich knowledge. Highly Appreciated ! Keep up the great work !
j pole better double than slimjim, the pattern totally diferent my friend.
Actually I see almost identical patterns but the slim jim has to go up higher than 10m (~30ft) to be more effective, check this article: www.hamradio.me/antennas/slimjim-vs-traditional-j-pole-antenna.html
This is still my favorite Ask Dave video
It's one of my favorites too. ;-)
His pole might not be perfectly straight but he demonstrates his skill with it like a real pro.
73 my dudes.
Exactly what D. Mckee said! I'm a new ham, and have been baffled by j-poles. Mystery solved! Thanks for your great work!
wonderful description specially the way of matching balance to unbalance (I mean the loop) perfectly clear
This is awesome. I've never heard it explained that way. So obvious now. Thanks!
I have made several J antennas for the FM broadcast band, centered at 98MHz, They work amazingly well.
Very nice explanation and presentation fella. I normally slip into a coma after 1 min of ham tutorials. But I got to the end of yours ok! 73's M0CPU
What a great explanation. I always understood a J-pole was 1/2 wave but the lower section/ matching confused me. I had assumed maybe I was dealing with a 3/4 wave in reality, which will match 50 ohms. Thanks.
Thanks for the run down. I took notes. I am about to build my first j-pole and this gives me everything I need to know about how they work and what the impedance does. AD5IX
Thanks for the great videos! They are clear and concise and I understand your explanatrions!
Wow, excellent job in explaining complicated topics.
Well done. Thank you. Operating with an Ed Fong J pole. Explains much.
this was amazing. i mostly understood it in the function of visual RF/wave form, though the explanation of voltage/current/impedance really solidified it.
1:12 "this is what you connect the antenna with"...
I think the word "mount" might have been better here, just a thought.. 🤔
I built a J pole years ago for my scanner and was delighted with the results !
Thanks for the vid, always worth watching and learning !
😎👍☘🍺
Brilliant video . I have used J Poles for many years now I understand how they work . 73 DE G7BWI
Your style reminds me of those educational/instructional TV shows back in the 1990s like: The New Yankee Workshop and Bob Vila's Home Again. I like it! One thing i'd like to see you add to your show is, by haps, a "set" in the background. It could be your radio shack or even a workshop since you also show how things are made.
I should ask viewers to submit photos to use as a background. Right now I use a background that came with my editing software, which I modified to include the OG! logo.
Hey Dave, I built a copper J-pole antenna today. It's Rx is fantastic, but on Tx my swr was 20+. I was worried I needed to rework the feedpoint, but after watching your video I realized that to match a balanced "feedline" (the 1/4 wave parallel section) to my UNbalanced feedline (coax), I needed a balun. After wrapping one up and attaching it, I was down to 1.4:1 on my selected freq. I realized I can get that even lower still with some trimming, as a few MHz below that was getting 1.2:1.
Thanks for the balun advice in there, it really helped me out! 73 KN6AZK
I'm glad it worked out well for you.
Would be great if you did an entire series on antenna designs and "how they work". I'm currently reading Joseph Carr's "Practical Antenna Handbook" and despite being extremely technical, learning a great deal about how antennas work. I would like to hear some of the material explained on your show!
I have an old copy of Carrs book and it is well worn. Joseph Carr was a great writer..
Ahoy sir!. I'm just getting back into the radio hobby after 24 yrs. I'm more of a listen than talk guy( scanner/SW). I have always been both facinated and intimidated by antennas and theory. Your vid was interesting and very simple to grasp. Would like to learn more about it, and get my entry level amateur license. Good job sir 👍
I'm a new HAM, and this was an excellent video for me.
Thank you, Dave, I always wondered how the J-Pole didn't short out the way it was designed.
Ten thumbs up! I finally understand the J-pole thanks to your visual explanation. 73, Bob
Thanks for making this easy to understand! I am researching to get into the radio hobby something I have put off for the last two decades because of elitist and needing good amount of time to learn everything to get things right. This was a great video! I look forward to diving into your channel. Subscribed and up voted.
That's the best explanation I have ever heard.
David, I'll join the chorus of kudos for such a wonderful explanation for what is such a mysterious device for many folks. (Hand raised) As you started with the dipole section, I visualized the current/voltage diagrams as seen in the old handbooks. Your explanation of the transmission line section tied it together. Not only did the proverbial light come on, but so many that we can now light up our Christmas tree, hi hi. Your video also indirectly explains why a mobile J-Pole would be impractical. There would be too much stuff (other cars, trucks, trees, curious people) that would interfere with the high impedance section. It also explains why it's best to have these high up in the air
Thanks again! 73 de KA0RFB
You're welcome! And thank you for the kind words!
This was pure genius! Just beginning my research and your wealth of knowledge is apparent. Thanks!
KF7BWS - Very fine explanation Dave. What a J Pole is, is an end fed zep.
I really enjoy instructional films like this one. Thank you David. 73!
Nice, clear explanation. I would add to be wary of grounding the bottom of the antenna, its supposed to be zero volts, but it never quite is, so you can get unpredictable things happening. Personally, I would keep the antenna insulated from a metallic mast.
Bravo! Thank you for an illuminating explanation! If I understand the matter correctly; At a DC voltage, it is a dead short, but at a VHF frequency, it is not shorted! I am not transmitting or receiving a DC signal so the dead short issue is moot! 73 Russell KE7QXR
Dave: One of the best educational RUclips videos I've seen; not only in the ham radio genre, but period. So I built a center loaded J-pole from some plans that is supposed to be dual band. Where does 70cm come in to the equation?
Thanks again,
Todd (AD0RR)
Hi Todd, I'm going to do a video soon building a kit 2-band J-pole, and I'll explain how it works on 70cm. Thanks for your suggestion! 73, Dave
Best explanation of a J-pole thanks
I love making things. I will definitely make a few antennas. This is a great explanation to something I found somewhat puzzling. 73s.
I knew most of those things separately, but you put it together beautifully in a way that makes sense! Thanks heaps for this video, you got yourself a new subscriber :D Cheers from down under!
Okay, this makes so much more sense now, I had always heard them described as a 3/4 wave antenna, now I get it, it's really a 1/2 wave with a rather strange feeder. In other words, if you removed the 1/2 wave section above the masking tape, although it would exibit a good VSWR, it would radiat very little to nothing, because, just like open twin lead transmission line, one side cancels out the other because they are 180 degrees out of phase and parallel to one another.
But the most interesting thing about this video is, I have always been in a controversy over which side of this to feed, and I have always feed them on the long side, and with my ground shield on the short leg thinking that it was a ground poise for a 3/4 wavelength antenna. But instead the bottom portion, is infact an impedance matching transformer for a 1/2 wave diapole, which requires no ground plane at all, but it does require a balanced feed which is why I can never get a really good VSWR. it's the same as trying to feed a center fed dipole, or an inverted V without louping the coax or running it through a ferrite bead or two.
Thanks Dave for a great explanation on how they work. Now it makes sense.
As Usual, a great explanation , you make it too easy, Thanks Dave!
Thank you! This is THE BEST explanation I've seen!
love the hidden lols with 101s great video thank you
I have always wondered what the science was regarding a j-pole! Very well explained!!! Fantastic video!
Kind regards,
Simon
M0SYS
Thanks for your videos. They are very informative. Keep up the great work!!
What an excellent demo. Well done !
Barry, KU3X
Best explanation I have heard of that antenna. Thanks. Hoping to make one.
Someone I know built a 6-meter J-pole. That thing was HUGE!
Yeah, it's the better part of a wavelength long from tip to tip.
Nice explanation, Dave! I really enjoyed the part where you explained how the end-feed works. I'd been wondering about that for some time.
That the coolest thing I learned today. Thank you Dave
Thank you for your sharing how to make
j-pole antenna..goodjob friend 👍
Thank you for this very in depth video of how the J-pole antenna works.
Just getting started in amateur radio, so I am like a sponge trying to learn this stuff. Great explanation on how it actually works. And how did I find this video? I am buying the Arrow Antenna J pole dual band for my 1st antenna. Small, functional and inexpensive (that's what the wife likes). Friend and I passed our tech test a month or so ago. Then he pass his General two weeks later. He's a Brainiac but I'm not. I have to learn it to understand it and not just learn questions and answers. You'll be seeing me a lot on here now. Thanks and 73's.
Happy New year Dave. Wow I have always wondered how one of these things work. That has to be the best video I have ever seen regarding a j pole. I guess it's the same for a slim Jim.
Fantastic video.
Motters
M7TRS 73's
Glad it was helpful! Yes, slim jims work the same way.
I wish I were smart enough to understand what this guy is taking about. I just passed my Technician exam last weekend. Maybe some day what he said will make sense to me.
Thank you. Your explanation makes a huge difference for this new ham. K9TOB
Most excellent explanation! Great work.
At 6:25 you mention getting the J-pole way up in the air, above your head. Can you give a little more detail on that ... is it a certain distance from the ground that matters, or not being next to your body / head? I have a portable J-pole on a stand that starts about chest height, so I'm wondering if I should avoid standing near it, or if it needs to be further off the ground, or what.
You explained this extremely well. Good stuff!
Very well explained! And in Metric too! Tnx, PD0PSX from the Netherlands.
Very nicely done Dave!
thank you for a really brilliant video - i love your teaching style, you make it really interesting and engaging, plus your videos are always really polished/professional ! thanks again ! (subscribed)
Dave love your videos . I am DE KC5ULU . I ask you about the omni charistics of the j-pole antenna . Heard your reply today thank you for taking time. I wanted to let you know my test site is in my back yard , maybe not optimum but works . I have a MFJ analizet the old 259 model which to my surprise will transmit a signal , it isn't strong but enough to see it on my Sedelco 733 super band field strength meter . My meter is a Seldco antenna meter covering the low mid and hi band vhf I have 40' of rg 6 run across the yard from a simple dipole antenna 30' away it allows me to tweak the receive meter to the transmit signal of the mfj 259 at one location . By doing this I am able to see a relative signal in microvolts . Now I can compare other antennas to each other or see how much better of an improvement I can get without asking someone else for a radio check, which we both know is useless. My receive antenna is 10' off the ground the test antenna is also 10' of the ground and I sit under the transmit antenna to get all my comparative readings. This is how I saw problems with some antennas J pole was one . I could grab the coax too to see if I get a meter movement indicating a common mode current on the outside of the coax . Now I am aware this is far from optimum , I know I have interference from reflections all around but for a simple test it seam to offer a world of important information. One great feature is that, a 3 element horizontal omni antenna I have been working on was mounted to an aluminum mast , then tried a pvc mast with a wooden insert for stiffener and it showed an improvement of "300 micro volts". Thats a huge improvement. AS it is my ssb 2 meter weak signal can hear 300 miles without any enhancement in the way. I have a pair of these 3 element phased antennas stacked 5' apart . It is the best I can find out there in omni. I compared a standard J-pole to a super J , WOW ! What a difference , also tried an J-beam and that to showed a great improvement in forward and rear rejection .this 1/2 wave end fire antenna was a great invention.