Hi, this is in effect not a dipole. It's a 1/4 lambda vertical with 1/4 lambda skirt of the shield braid that acts to stop the common mode current that tends to flow along the outer skin of the shield braid. You do have a coax cable 1:1 choke BalUn too to serve the same purpose. Instead it can take the form of a ferrite loaded CMC (common mode choke) by having 8 turns of the same coax cable wound on an FT240-43. There can be 4 turns on one side of the toroid with the cross winding of the other four turns (Joe Reisert's style) to have the ends on the opposite sides of the toroid. If needed you can have a suitable ABS or Polycarbonate water tight and weather proof box with 2×SO239 connectors mounted that can be detached for easy portability. And you are trimming the 1/4 lambda vertical radiator only but not the shield braid of the coax cable for obtaining the lowest SWR. Thanks for the post. De VU2RZA
Whats the difference, the inner is one half of the antenna, the outside of shield/screen is the other. No different than running the coax up to a dipole. The coil just takes the rest of the screen out of the equation without affecting the current on the inner conductor and the inside of the screen. You just have to remember that to RF the inner surface of the braide is totally isolated from the outer surface. Only where the braide stops does the rf current start to flow on the outside as it turns the corner, and the Inside becomes the outside.
It's a sleeved dipole. The second "half" of the dipole is the coax outer before the RF choke at the bottom. This design is generally known as a "flowerpot" antenna. As an aside, I suspect if you wanted to make it lighter, you could use a thin piece of wire for the top 5m and solder it onto the inner of the length of coax. That way you use 5m less coax and make the whole thing a bit lighter and cheaper. Edit: I see Peter's made the same comment below!
@@paulsengupta971 I like it, it's a sleeved dipole, a 1/4 Lambda vertical, or just a plain old 1/2 dipole. 1/2 wavelength each side of a coax feed point. you could just cut the coax and connect to 2 x 5m bits of wire soldered to the end. which is in affect 5m inner, plus 5m of outside skin of the braid. and the choke to disconned the rest of the braid from the RF. sorry Flower pot as well ;-)
@@TheEmbeddedHobbyist hi, a centre fed dipole is a symmetric device with the feeder connected at the centre of the half lambda long radiator (quarter lambda sections on either side). If erected properly in free space, there is no need for a CMC (common mode choke) that would otherwise be required to stop the current flowing down from the feed point to the transmitter along the outer skin of the coax cable braid. The radiation pattern you get would be the typical donut with broadside radiation and nulls on the ends of the radiator and a feed impedance of around 75 ohm (in the case of flat top configuration) and a sort of omnidirectional pattern with reduced feed impedance around 50 ohm in the case of inverted V installation. Now you can tell me what kind of radiation pattern this so called "center fed vertical dipole" would have to offer and the role of the feeder with respect to the radiator. How do you assure symmetry in the contraption!?
This design goes back many years and was popular on VHF. You can replace the coil with a few turns around a ferrite core. Rather than struggling with stripping back all that outer coax covering, simply solder a 510cm length of single cor to coax inner and seal with glue gun. Peter G3OJV
Thanks for the information Peter. I wonder how many turns and what type of ferrite would work? I guess it could even be put into a box? And then have an SO239 socket so a coax feeder can be attached easily. I also wonder how this design would perform against the design in the video. PS. I Enjoy your videos Peter, keep them coming! Thanks, Matt, M0DQW
@@TechMindsOfficial it’s really similar to the 2M “Flower Pot” antennas that a short Duck Duck Go will reveal There is also a 5/8 wave design that inserts capacitance to physically extend the top element and a tuning stub on the lower half of the antenna. While aimed at the 10m (11m) crowd, I’m sure it would extend out to 20m at around 42’ or 12.5m long. I had some success with a shortened 3/4 wave on 20m brought down to that 0.625 - 0.64 wavelength physical size using a ground plane. I’m working on an end fed version that is 1/2 wave for 40m, full wave for 20m and 5/8 waveish tall
Once you get the hang of stripping back the coax it's not a drama. The fiddliest part of it was cutting the plastic outer sheath although in hindsight a piece of scrap timber with a groove cut into it to lay the coax in would have made even quicker and safer. I liked the idea of a single piece of coax all the way to the transceiver without any connections. I might try the ferrite core(s) as a common mode choke in place of the coil. It would make the whole arrangement a little less bulky. 73 Y
@@yamakawa511 true. Effectively this is the technique I use to ground my 40m mobile antenna on the mag mount. Technically, coax can be considered a 3 conductor cable. Core, inside the shield and outside the shield. I use the outside shield to capacitively couple to the car body by running it tightly down the pillar and along the floor pan before it hits the radio. There is a common mode choke 30cm before it hits the radio. Matches neatly across the bottom 100KHz of 40m for mobile CW operation and the lower portion of the aussie voice segment The common mode choke breaks the outer shield as a conductor at RF. Science !!!!!! :-)
Fun watching your vid. Just a comment from an old guy, the outer sleeve is called a Bazooka or Sleeve Choke, and a few other terms. Worked good 60+ years ago when I made my first one for 10 meters during Cycle 19. They still work good. And yes some of you guys will want to jazz it up with ferrites or capacitors, etc. There is still efficiency in the simplest version with a single piece of coax and no cutting, soldering, etc. And the braid you slipped off the tip makes really nice ground straps and such. k8do
Nice idea! I am using this popular design for VHF vertical dipole few years and I am satisfied. Instead removing the outer braid and plastic jacket of the coaxial cable (which can be pretty much difficult), I suggest the use simple piece of wire (510 cm length) soldered to the inner central conductor of the coaxial cable.
I'm running one of these for 10m now, it works better than any single wire antenna I tried. i also made a 2m version and 70cm version. The 70cm is cute...15-16cm radiator, 3 turns of coax around a 25mm former as a choke, I think it's about 18 inches of coax in total and works fantastically on my HT. All of them are 1:1.05 or less SWR.
K)MAN, I built this antenna and added a Reflector and Director using 8' spacing, just to see if it worked and WOW did it work GREAT! So I put up an Array. This consists of one Reflector at the center, 4 Driven Elements, ( One every 90 degrees) and 4 Directors, (One every 90 Degrees). I used an Ameritron remote coax switch to select the driven elements. The antenna is a Winner on 20 Meters and can be fashioned for any band 10-20 meters. Using fiberglass poles from DX Engineering, 12 meter vertical poles were easy to build. I used 5 gallon paint buckets filled with concrete and a pipe sticking out to slip the squid poles onto. I fed each Radiator with a 1/4 wave 75 ohm coax which became a delay line and turned the non used Radiators into additional reflectors which enhanced the forward gain. I am getting 2 to 5 S units of gain over a 20 meter Dipole at 20'!! Seeing how the DX Commander is built and using some old Quad antenna designs, I am thinking this antenna could be a 5 band array, but is going to be a wire nightmare!! Jim K0MAN
Thanx fer the video! I built one and it works great on 20 meters. I ran it up a 12 meter Spiderpole mounted on a drive over stand for portable use. Works like a charm for my POTA ops… 73 Fred W0SP
This antenna has been described in an ARRL Handbook decades ago for several bands and types of coax. Excellent performance was obtained for the 20 and 30m version I build. Good luck and good DX with yours. 73's, Patrick ON4KNP/OT5Q
Hi Mat another excellent tutorial video as always, I have made the same antenna but used 13 turns round a 4 inch former and a length of wire instead of the center dielectric, I worked 6 new dxcc on my first outing and was well impressed, I use the 12m spiderbeam to mount the antenna. Good dx 73.
I made this antenna about 2 months ago, comparing it to my 20m dipole and 20m DX Commander antenna, I was pleasantly surprised how well it performs, although I only had 75ohm coax laying around I have been able to work most of the world so far. SWR is around 1:1 - 1.5 at 14-15mhz. It is typically my go to antenna for 20m DXing. Thanks for the video! 73.
I built this vertical two weeksmago and tested it today. WOW it worked like a charm. I didn't have straight up but rather at a 45 degree angle. It read 1:1 & 1:2 across the General band here in the US. Thankmyou, thank you! KI5IQE
Hi, Yes I made a couple of these T2LT type antennas for the 11m band, one for me & one for my son who is currently not licensed for HAM radio. these both worked great both at home & on holiday. I saw you video last night & I thought I would give this 20m version a try, luckily I had 20 metres of RG58 left on a spool in the shack, so I got started today & it was all done in just over an hour, unfortunately, I ran out of time & could not set it up on the mast to test it, I did however, stick a meter on it & found it to be showing 1.674 Ohms at the plug end, all continuity checks where ok, no shorts. I double checked the entire build & everything is as per the specs given, I can't see chopping or adding a few cm's making much difference. I will have another look tomorrow during the day & see how it goes. Thanks for the video.
UPDATE !! ... I got to test the antenna today 28/07/22, I put a piece of heat-shrink tube at the 510cm point of the radiating section as a reference point when tuning, then folded the tip over at that point, held in a loop by another piece of heat-shrink tube so it was easy to slide & make adjustments. I found this unnecessary as it was under 1.5 across the 20m band, also to my surprise, my usual S7 to S9 noise floor reduced to S3 to S4 at the low end of the band & S5 to S6 on the higher part, I heard quiet a few stations out there, but most were running pile-ups which I doubt I would have broken through with my X6100 on 5w (internal battery powered), I will try for some reports during next week. I am surprised at how well this antenna is working so far.
hi, just built this kind of antenna for 6m and use a 6m fishing rod 10 days ago. Instead to strip cable I use 1mm2 wire. I tuned cutting wire and moving the coil ... it is a great antenna compared the cost.... .... now looking for a more then 12 m fiberglass rod.
You can save yourself 5m of coax if you solder a piece of standard insulated wire to the end of the coax center conductor instead of stripping 5m of shield away. Good to see people still using flower pot antennas these days though. I use one on 2m Another interesting video Matt
Thanks Paul, my first experience of these types of antennas was when I made a 70mhz antenna, worked pretty well. Interesting idea about soldering a piece of wire instead of stripping the coax, I wonder how critical the wire type would need to be, velocity factor etc. Might have to experiment some more! Cheers
@@TechMindsOfficial Velocity factor is only a thing for transmission lines. Once you're down to a single conductor it's not applicable any more. Using a different wire than the coax center for one end of the dipole will work just fine. It'll have slightly different inherent capacitance than the center of the RG58, but you have to cut it resonance by trial and error anyway so it won't make any difference in the end. The difference in required length between using copper plumbing pipe or 30AWG aluminum wire will only be a centimeter or two.
Mat: I just finished a ten meter T2LT, but with RG-11 as I had a spool end on hand. It's used for long cable TV runs locally, and the partial spools are available free or cheap. I ran out of dry weather and will be testing it Saturday (November 12, 2022). I will comment here when I see how it plays... De WB2VUO here near Buffalo, NY
The late Robert Victor, VA2ERY of Miracle Antenna fame sold back around 2010 a “mixed mode coax dipole” as he called it that he made from RG-174u with a ferrite common mode choke. It was fundamentally exactly like this. He terminated his antenna with a BNC connector. The key thing to be mindful is the common mode current must be choked off, and the antenna Is resonant to single band use only.
i built a hard aluminum center fed vertical for 17m that swivels like a windmill blade into a sloper. Bottom is only 75cm off ground, but it absolutely rocks on dx.
I made some Yesterday Matt works well and fits in the Rucksack! I made them for 4, 6, 10, 17 & 20 all work fine I also tried as Peter suggested but the ferite adds weight
I built one for the VHF aviation band. But used coax (RG58) only for the counterpoise (54cm) and the coil (11 turns on a 26mm former) and spliced/soldered (59cm) PVC jacketed 14 gauge (AWG) for the driven element. Countepoise and driven element taped to a 13mm PVC pipe for operation. Low SWR of 1.08 at 120MHz remaining below 1.5 between 118.5 and 122MHz. Gonna do a repeat for 6 meters later this year
You can never go wrong with a well matched dipole, if you have the room for it, vertically or horizontally. Good built, perfect result. I may build one for the 10m band, how is the coil calculated?
Nice attempt. I would caution against mounting a half wave vertical much above 10 ft agl as any higher will begin to reduce gain at low angles on HF (for dx). I have made versions for 20,15,10 and 2m on my channel. 73
I have build the T2LT antenna for the CB band. I found the SWR variable with the position of the feed line. I mean put the feed line coax in a different spot then i saw that back in the SWR. That's not good... So instead i made a double bazooka coax antenna and that thing is a winner.
@@timg5tm941 Roger that. But i even used two chokes. One ugly balun like most people seem to use with this type antenna and i also had a ferrite 1:1 balun in action. So yeah you are right. But i ruled that out and i don't have much confident in this antenna. Double bazooka outperforms it anyway and is the same concept :)
I made this antenna over the weekend and used it today to activate my first park with my Xiegu G90 running 20 watts. Longest contact was 900 miles. ALL of my contacts were to the west or due south. Is this antenna directional in any way or was this likely a function of the band conditions?
Pretty cool, a 20M version of an old end fed dipole. It relies on the common mode currents flowing on the outside of the shield and that coil as a choke to "end the antenna". I built one years ago, but used a ferrite toroid instead of the huge coil. Employed it as a tilted dipole fed from the end... Enjoy your vids. de wb7ond
@@justme-n-gracieno Steve. Its a dipole. Electrically exactly the same. You're confused as you're assuming the antenna is grounded at the physical feedpoint. It isn't. Current flows up the coax, the shield ends, current flows down the exterior surface of the shield and is prevented from being grounded by the choke. It's all radiator. It has two poles. A monopole antenna is half radiator, half ground. This is not the case here. If you need further information I suggest you look up sleeved dipoles, they're used for reference measurement work. To quote one of the data sheets: "These antennas are truly omnidirectional antennas, having an electric dipole pattern approaching that of a half-wave resonant dipole with typical gains between 1.5 and 2.0 dB. The sleeve dipole design allows the antenna to be end-fed to avoid cable and feedpoint interactions that interfere with the performance of the antenna. Integral quarterwave chokes and/or ferrite loading (depending on frequency range) also help to reduce cable interaction. This design also provides exceptional symmetry (typically better than 0.1 dB (0.2 dB peak-to-null)) to meet or exceed CTIA criteria for ripple test antennas."
Hi Mat I have built 2 of them 1 for 2m and the other for the uk CB band both work well field testing them at moment along with a new super antenna MP1 M7CVK
A ten metre fibreglass pole in an urban garden in the UK? Lucky chap, you have nice neighbours because if I did that I could expect a visit from the council within a week.
I have a 9m pole 1m off the ground on a tripod stand at the bottom of my garden. I attached a windsock/flag thing to the top to make it look not like an antenna 🤣
Built one out of curiosity. Does great, as good or slightly “better” than the many half wave wire verticals (w/49:1’s) i’ve put up, but with lower swr and no radials
With RG58, probably around 300 watts on SSB. If you use RG8-x, it can withstand double or more watts. Using thicker coax such as RG213 with length for 20 meter band, will be very heavy.
Built a t2lt for 11m a week ago same design it works very well was surprised 7m of coax and a £25 KIT POLE IT GETS ME FROM THE MIDLANDS INTO EUROPE NO PROBLEM 40WATTTS NEARLY A thousand miles
You will find that is an upscale version of most 2.4GHz coaxial dipoles inside those plastic covers on your WiFi router :-) The choke (24t on the former) isn't usually critical.
Well, I am having a conversion (imperial to metric) crisis; in that a 68mm diameter does not have an equivalent imperial size. I am looking at either a 60.3mm or a 75.2mm diameter. That translates to a 2" or a 2.5" standard drain pipe. How does that change the number of turns needed to electrically lengthen the antenna? It has to be different doesn't it? I dunno because I am not well versed or learned in Antenna science and lore just yet. I am however, a patient old(er) padawan. Please help me Obi Wan...
Nice to see you are getting on well with the HL2. Maybe you could do a review of that mast too as it looks useful but a bit too expensive for an impulse purchase! The spec suggests it could be used for a medium sized yagi (6m 5ele maybe), presumably when guyed, but don't know how that would pan out in reality?
Really nice video I’m curious did you do any type of calibration on your analyzer after you got it in the mail or was it ready to go as soon as you received it
World's simplest antenna, just one piece of coax! I don't think I've actually seen anyone do this before but a lot of little Wi-Fi antennas are made this way.
Firstly, mate 17 meters of coax isn't cheap but neither is that 50' Moonraker pole! Cost more that my G90 that I got on sale. LOL. Since I am not skilled yet in antenna what would it take to do 28.3 to 28.5MHz? That's my lot in HF land until 12 August when I will pass my General and spread my HF wings. Love to build one and report back what happened.
RG58 is probable the cheapest you can get. But please, let us know how you get on! I believe there are plans out there for use on 10m, maybe I will make a video on it..
The problem is that to get an efficient antenna on the lower bands, you'd need a very tall insulated pole/mast. While a smaller antenna will work (maybe with a tuner) it might be better to create some sort of inverted V.
Nice one matt. Tim G5TM also made a video on this fairly recently. I believe it wouldn't be too difficult to phase 2 of these for some useful gain & nulling out QRM. I already have have the phasing kit. At most a matching circuit would be needed at the phasing relay box.
Really looking forward to that once Colin - I take it you are looking at quarter wave distance or half wave between them? I might try that for 10m to see the front to back.
@@timg5tm941 I will initially try 1/8th wave then 1/4 wave if the former doesn't work. As Justin explains and as I understand it, the phasing/delay line lengthsbhave a direct realationship to the spacing and not the type of antenna.
Hi - just my thoughts - confirm the coax cable’s basic power rating for the frequency and then perhaps improve the basic common mode choke if you want to go QRO.
Excellent ant for 20m if you cannot fit radials in, I myself use a 5m painters pole with radials, less height not seen as much, and I have just recently added a parasitic reflector, and boy does it work, especially for long distance dx , 10,000k and more. Thanks 73 zl3xdj
Had a go at making this today, I only had pipe about 40mm in diameter? SWR was off the scale, I was under the impression it was the number of turns not the diameter. Can you enlighten me please?
@@paulkazjack I lost interest and instead made a 14mhz/20m centre fed cage dipole, three lightweight lengths of wire separated by some plastic drainpipe cut into thing slices as spacers. It has a 1:1 balun at the feed point. I've worked a lot of stations worldwide on SSB and FT8 using QRP power of 10 watts. SWR is 1 to 1.1/1.2 across the band due to the increased bandwidth the cage effect gives. No ATU necessary.
Nice to see you use the hl2 :) Can'tget mine to transmit, no rf output even with drivers all up etc nor sure what it is. Maybe somethong for a video ? The t2lt is nice and simple. Made several of them, dedicated monoband antennes alway work good for me.
Hi - sorry it didn’t work for you ! First thought is to check the antenna is not shorted ( an Ohm meter connected to the coax connector should read open circuit).
@@davidw460 found the problem. 😞 Forgotten to Power the watt meter, oeps. Tune gives me 5 to 8 Watt but audio is very distorted and low gain. Explained why nobody responded on my calls. Haven't solved that yet must be also configurstion mistake. Antenna is a 3 band high-endfed no problem with that on my ft950.
I just made this antenna, but instead for 15M and wound the coax around a large ferroid choke. Waiting on the mast to arrive and then I'll be putting it up! I also took Peter G3OJV's suggestion and soldered a solid wire at the end of the coax instead of stripping off all that dialectric.
This looks like a flowerpot antenna I built for 2m when I first got my tech back in 2017...great video and thanks for sharing...I may give this a try sometime. :-D 73 KN4FTT
Im absolutely amazed by how is your SDR Console set to display that high resolution of received signal! Could you make an instuctional video about SDR Console please?
Its described as a vertical dipole, so one would asume it could be used horizontally? like say a traditional centre fed. This is cheap as chips so defo worth a try.
A common mistake is for people to use the formula 234 / frequency in megahertz for their measurement of both the top and the bottom half, which results in a too Short antenna and an antenna that tunes higher than anticipated. The reason for this is because End Effect is employed in the formula 234 / frequency in megahertz - ONLY for the top quarter wave since the bottom quarter wave is terminating at a choke. There will be no End Effect therefore the bottom half should be the full quarter wave or 108 inches for 11m CB use whereas the top half will end up tuning best somewhere around 103 inches for center of the USA 11m CB band.
That is NOT a vertical dipole! Sorry to break the news. To be a VD it needs an element outside the coax for 1/4 wavelength and tied into the shield at the pint where the inner coax element goes up 1/4 wl. I build them this way using the coax shield pulled down around the coax. To do that on lower bands so far intimidates me. I may try it with copper tape though. Some call this a Flower Pot design. It needs no Coils at the bottom.
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Hi, this is in effect not a dipole. It's a 1/4 lambda vertical with 1/4 lambda skirt of the shield braid that acts to stop the common mode current that tends to flow along the outer skin of the shield braid.
You do have a coax cable 1:1 choke BalUn too to serve the same purpose.
Instead it can take the form of a ferrite loaded CMC (common mode choke) by having 8 turns of the same coax cable wound on an FT240-43. There can be 4 turns on one side of the toroid with the cross winding of the other four turns (Joe Reisert's style) to have the ends on the opposite sides of the toroid. If needed you can have a suitable ABS or Polycarbonate water tight and weather proof box with 2×SO239 connectors mounted that can be detached for easy portability.
And you are trimming the 1/4 lambda vertical radiator only but not the shield braid of the coax cable for obtaining the lowest SWR.
Thanks for the post.
De VU2RZA
Thanks for your response 👍❤️
De VU2RZA
Whats the difference, the inner is one half of the antenna, the outside of shield/screen is the other. No different than running the coax up to a dipole. The coil just takes the rest of the screen out of the equation without affecting the current on the inner conductor and the inside of the screen. You just have to remember that to RF the inner surface of the braide is totally isolated from the outer surface. Only where the braide stops does the rf current start to flow on the outside as it turns the corner, and the Inside becomes the outside.
It's a sleeved dipole. The second "half" of the dipole is the coax outer before the RF choke at the bottom. This design is generally known as a "flowerpot" antenna.
As an aside, I suspect if you wanted to make it lighter, you could use a thin piece of wire for the top 5m and solder it onto the inner of the length of coax. That way you use 5m less coax and make the whole thing a bit lighter and cheaper. Edit: I see Peter's made the same comment below!
@@paulsengupta971 I like it, it's a sleeved dipole, a 1/4 Lambda vertical, or just a plain old 1/2 dipole. 1/2 wavelength each side of a coax feed point. you could just cut the coax and connect to 2 x 5m bits of wire soldered to the end. which is in affect 5m inner, plus 5m of outside skin of the braid. and the choke to disconned the rest of the braid from the RF. sorry Flower pot as well ;-)
@@TheEmbeddedHobbyist hi, a centre fed dipole is a symmetric device with the feeder connected at the centre of the half lambda long radiator (quarter lambda sections on either side).
If erected properly in free space, there is no need for a CMC (common mode choke) that would otherwise be required to stop the current flowing down from the feed point to the transmitter along the outer skin of the coax cable braid.
The radiation pattern you get would be the typical donut with broadside radiation and nulls on the ends of the radiator and a feed impedance of around 75 ohm (in the case of flat top configuration) and a sort of omnidirectional pattern with reduced feed impedance around 50 ohm in the case of inverted V installation.
Now you can tell me what kind of radiation pattern this so called "center fed vertical dipole" would have to offer and the role of the feeder with respect to the radiator.
How do you assure symmetry in the contraption!?
This design goes back many years and was popular on VHF. You can replace the coil with a few turns around a ferrite core. Rather than struggling with stripping back all that outer coax covering, simply solder a 510cm length of single cor to coax inner and seal with glue gun. Peter G3OJV
Thanks for the information Peter. I wonder how many turns and what type of ferrite would work? I guess it could even be put into a box? And then have an SO239 socket so a coax feeder can be attached easily. I also wonder how this design would perform against the design in the video. PS. I Enjoy your videos Peter, keep them coming! Thanks, Matt, M0DQW
@@TechMindsOfficial it’s really similar to the 2M “Flower Pot” antennas that a short Duck Duck Go will reveal
There is also a 5/8 wave design that inserts capacitance to physically extend the top element and a tuning stub on the lower half of the antenna. While aimed at the 10m (11m) crowd, I’m sure it would extend out to 20m at around 42’ or 12.5m long.
I had some success with a shortened 3/4 wave on 20m brought down to that 0.625 - 0.64 wavelength physical size using a ground plane. I’m working on an end fed version that is 1/2 wave for 40m, full wave for 20m and 5/8 waveish tall
Once you get the hang of stripping back the coax it's not a drama. The fiddliest part of it was cutting the plastic outer sheath although in hindsight a piece of scrap timber with a groove cut into it to lay the coax in would have made even quicker and safer. I liked the idea of a single piece of coax all the way to the transceiver without any connections. I might try the ferrite core(s) as a common mode choke in place of the coil. It would make the whole arrangement a little less bulky. 73 Y
@@yamakawa511 true. Effectively this is the technique I use to ground my 40m mobile antenna on the mag mount.
Technically, coax can be considered a 3 conductor cable. Core, inside the shield and outside the shield. I use the outside shield to capacitively couple to the car body by running it tightly down the pillar and along the floor pan before it hits the radio. There is a common mode choke 30cm before it hits the radio. Matches neatly across the bottom 100KHz of 40m for mobile CW operation and the lower portion of the aussie voice segment
The common mode choke breaks the outer shield as a conductor at RF.
Science !!!!!! :-)
@@TechMindsOfficial one example here g0kya.blogspot.com/2010/11/efhw-monoband-end-fed-half-wave-for-10m.html
Fun watching your vid. Just a comment from an old guy, the outer sleeve is called a Bazooka or Sleeve Choke, and a few other terms. Worked good 60+ years ago when I made my first one for 10 meters during Cycle 19. They still work good. And yes some of you guys will want to jazz it up with ferrites or capacitors, etc.
There is still efficiency in the simplest version with a single piece of coax and no cutting, soldering, etc. And the braid you slipped off the tip makes really nice ground straps and such. k8do
Nice idea! I am using this popular design for VHF vertical dipole few years and I am satisfied. Instead removing the outer braid and plastic jacket of the coaxial cable (which can be pretty much difficult), I suggest the use simple piece of wire (510 cm length) soldered to the inner central conductor of the coaxial cable.
I'm running one of these for 10m now, it works better than any single wire antenna I tried. i also made a 2m version and 70cm version. The 70cm is cute...15-16cm radiator, 3 turns of coax around a 25mm former as a choke, I think it's about 18 inches of coax in total and works fantastically on my HT. All of them are 1:1.05 or less SWR.
K)MAN, I built this antenna and added a Reflector and Director using 8' spacing, just to see if it worked and WOW did it work GREAT! So I put up an Array. This consists of one Reflector at the center, 4 Driven Elements, ( One every 90 degrees) and 4 Directors, (One every 90 Degrees). I used an Ameritron remote coax switch to select the driven elements. The antenna is a Winner on 20 Meters and can be fashioned for any band 10-20 meters. Using fiberglass poles from DX Engineering, 12 meter vertical poles were easy to build. I used 5 gallon paint buckets filled with concrete and a pipe sticking out to slip the squid poles onto. I fed each Radiator with a 1/4 wave 75 ohm coax which became a delay line and turned the non used Radiators into additional reflectors which enhanced the forward gain. I am getting 2 to 5 S units of gain over a 20 meter Dipole at 20'!! Seeing how the DX Commander is built and using some old Quad antenna designs, I am thinking this antenna could be a 5 band array, but is going to be a wire nightmare!!
Jim K0MAN
They do work well, have built a few in the past, from 2 meters to 20 meter bands,easy build, and cheap!
Thanx fer the video! I built one and it works great on 20 meters. I ran it up a 12 meter Spiderpole mounted on a drive over stand for portable use. Works like a charm for my POTA ops… 73 Fred W0SP
Exactly what i use for POTA
This antenna has been described in an ARRL Handbook decades ago for several bands and types of coax. Excellent performance was obtained for the 20 and 30m version I build. Good luck and good DX with yours. 73's, Patrick ON4KNP/OT5Q
Do you recall which one or what article?
Awesome video matey as usual :) and its fab to have you as a member of the G8AMC :)
Hi Mat another excellent tutorial video as always, I have made the same antenna but used 13 turns round a 4 inch former and a length of wire instead of the center dielectric, I worked 6 new dxcc on my first outing and was well impressed, I use the 12m spiderbeam to mount the antenna. Good dx 73.
I made this antenna about 2 months ago, comparing it to my 20m dipole and 20m DX Commander antenna, I was pleasantly surprised how well it performs, although I only had 75ohm coax laying around I have been able to work most of the world so far. SWR is around 1:1 - 1.5 at 14-15mhz. It is typically my go to antenna for 20m DXing. Thanks for the video! 73.
I built this vertical two weeksmago and tested it today. WOW it worked like a charm. I didn't have straight up but rather at a 45 degree angle. It read 1:1 & 1:2 across the General band here in the US. Thankmyou, thank you! KI5IQE
Hi, Yes I made a couple of these T2LT type antennas for the 11m band, one for me & one for my son who is currently not licensed for HAM radio. these both worked great both at home & on holiday. I saw you video last night & I thought I would give this 20m version a try, luckily I had 20 metres of RG58 left on a spool in the shack, so I got started today & it was all done in just over an hour, unfortunately, I ran out of time & could not set it up on the mast to test it, I did however, stick a meter on it & found it to be showing 1.674 Ohms at the plug end, all continuity checks where ok, no shorts. I double checked the entire build & everything is as per the specs given, I can't see chopping or adding a few cm's making much difference. I will have another look tomorrow during the day & see how it goes. Thanks for the video.
UPDATE !! ... I got to test the antenna today 28/07/22, I put a piece of heat-shrink tube at the 510cm point of the radiating section as a reference point when tuning, then folded the tip over at that point, held in a loop by another piece of heat-shrink tube so it was easy to slide & make adjustments. I found this unnecessary as it was under 1.5 across the 20m band, also to my surprise, my usual S7 to S9 noise floor reduced to S3 to S4 at the low end of the band & S5 to S6 on the higher part, I heard quiet a few stations out there, but most were running pile-ups which I doubt I would have broken through with my X6100 on 5w (internal battery powered), I will try for some reports during next week. I am surprised at how well this antenna is working so far.
hi, just built this kind of antenna for 6m and use a 6m fishing rod 10 days ago. Instead to strip cable I use 1mm2 wire. I tuned cutting wire and moving the coil ...
it is a great antenna compared the cost....
.... now looking for a more then 12 m fiberglass rod.
You can save yourself 5m of coax if you solder a piece of standard insulated wire to the end of the coax center conductor instead of stripping 5m of shield away.
Good to see people still using flower pot antennas these days though. I use one on 2m
Another interesting video Matt
Thanks Paul, my first experience of these types of antennas was when I made a 70mhz antenna, worked pretty well. Interesting idea about soldering a piece of wire instead of stripping the coax, I wonder how critical the wire type would need to be, velocity factor etc. Might have to experiment some more! Cheers
i was just thinking of using a 10m rg58 patchlead with a soldered 5m end? hmmm
@@TechMindsOfficial Velocity factor is only a thing for transmission lines. Once you're down to a single conductor it's not applicable any more. Using a different wire than the coax center for one end of the dipole will work just fine. It'll have slightly different inherent capacitance than the center of the RG58, but you have to cut it resonance by trial and error anyway so it won't make any difference in the end. The difference in required length between using copper plumbing pipe or 30AWG aluminum wire will only be a centimeter or two.
M7RJJ here. Gave it a try. First contact in to Italy in daytime running 10 watts on 20 metres
That’s great news! Better satisfaction knowing you made it yourself too! Cheers
Thank you for this, it is what I have been looking for with portable.
You’re welcome 😉
Mat: I just finished a ten meter T2LT, but with RG-11 as I had a spool end on hand. It's used for long cable TV runs locally, and the partial spools are available free or cheap.
I ran out of dry weather and will be testing it Saturday (November 12, 2022). I will comment here when I see how it plays...
De WB2VUO here near Buffalo, NY
The late Robert Victor, VA2ERY of Miracle Antenna fame sold back around 2010 a “mixed mode coax dipole” as he called it that he made from RG-174u with a ferrite common mode choke. It was fundamentally exactly like this. He terminated his antenna with a BNC connector. The key thing to be mindful is the common mode current must be choked off, and the antenna Is resonant to single band use only.
Thank you for sharing this information 🙏
Where is the link to buy this in the US? Could not tell which one it was in the Amazon store.
i built a hard aluminum center fed vertical for 17m that swivels like a windmill blade into a sloper. Bottom is only 75cm off ground, but it absolutely rocks on dx.
I made some Yesterday Matt works well and fits in the Rucksack! I made them for 4, 6, 10, 17 & 20 all work fine I also tried as Peter suggested but the ferite adds weight
Could you send me the plans for them all I would definitely appreciate it very much. My name is William Peacock AE4OY .73
I built one for the VHF aviation band. But used coax (RG58) only for the counterpoise (54cm) and the coil (11 turns on a 26mm former) and spliced/soldered (59cm) PVC jacketed 14 gauge (AWG) for the driven element. Countepoise and driven element taped to a 13mm PVC pipe for operation. Low SWR of 1.08 at 120MHz remaining below 1.5 between 118.5 and 122MHz.
Gonna do a repeat for 6 meters later this year
I made a 2m version of that antenna back in high school and it's probably the best performing antenna I've ever built
You can never go wrong with a well matched dipole, if you have the room for it, vertically or horizontally. Good built, perfect result. I may build one for the 10m band, how is the coil calculated?
Google "coax choke balun" or "Ugly balun". There are designs out there.
Hi look up flowerpot antenna, gives instructions for a 2m 70 cm antenna, it works well.
Nice attempt. I would caution against mounting a half wave vertical much above 10 ft agl as any higher will begin to reduce gain at low angles on HF (for dx). I have made versions for 20,15,10 and 2m on my channel. 73
Hi sir could you please give me the specifications for the antennas you built thanks 9z4apa 73s.
I have build the T2LT antenna for the CB band. I found the SWR variable with the position of the feed line. I mean put the feed line coax in a different spot then i saw that back in the SWR. That's not good... So instead i made a double bazooka coax antenna and that thing is a winner.
If adjusting the coax changes the swr it means your choke might’ve been insufficient to choke off common mode
@@timg5tm941 Roger that. But i even used two chokes. One ugly balun like most people seem to use with this type antenna and i also had a ferrite 1:1 balun in action.
So yeah you are right. But i ruled that out and i don't have much confident in this antenna. Double bazooka outperforms it anyway and is the same concept :)
I made this antenna over the weekend and used it today to activate my first park with my Xiegu G90 running 20 watts. Longest contact was 900 miles. ALL of my contacts were to the west or due south. Is this antenna directional in any way or was this likely a function of the band conditions?
Awesome! Don’t believe it’s directional, so possibly band conditions depending on your location. Good job!
How did you terminate the top for hoisting or connecting to your pole?
Think I just taped it to the top of the pole using electrical tape.
What is callsign around 7min30 sec ? thanks
Hello Fellas,thanks for sharing this design, it works fantastic, would you have the measurements to build one for the 15m band?Thanks
Pretty cool, a 20M version of an old end fed dipole. It relies on the common mode currents flowing on the outside of the shield and that coil as a choke to "end the antenna". I built one years ago, but used a ferrite toroid instead of the huge coil. Employed it as a tilted dipole fed from the end... Enjoy your vids. de wb7ond
@@justme-n-gracieno Steve. Its a dipole. Electrically exactly the same.
You're confused as you're assuming the antenna is grounded at the physical feedpoint. It isn't.
Current flows up the coax, the shield ends, current flows down the exterior surface of the shield and is prevented from being grounded by the choke.
It's all radiator. It has two poles.
A monopole antenna is half radiator, half ground. This is not the case here.
If you need further information I suggest you look up sleeved dipoles, they're used for reference measurement work.
To quote one of the data sheets: "These antennas are truly omnidirectional antennas, having an electric dipole pattern approaching that of a half-wave resonant dipole with typical gains between 1.5 and
2.0 dB. The sleeve dipole design allows the antenna to be end-fed to avoid cable and feedpoint interactions that interfere with the performance of the antenna. Integral quarterwave chokes and/or ferrite loading (depending on frequency range) also help to reduce cable interaction. This design also provides exceptional symmetry (typically better than 0.1 dB (0.2 dB peak-to-null)) to meet or exceed CTIA criteria for ripple test antennas."
Hi Mat I have built 2 of them 1 for 2m and the other for the uk CB band both work well field testing them at moment along with a new super antenna MP1 M7CVK
i built a set of these these about 40 years ago - i still have them - 6/10/20/40(needs a big tree) - they just work
Is there any concern with using RG-6 or RG-59?
A ten metre fibreglass pole in an urban garden in the UK? Lucky chap, you have nice neighbours because if I did that I could expect a visit from the council within a week.
I have a 9m pole 1m off the ground on a tripod stand at the bottom of my garden. I attached a windsock/flag thing to the top to make it look not like an antenna 🤣
Built one out of curiosity. Does great, as good or slightly “better” than the many half wave wire verticals (w/49:1’s) i’ve put up, but with lower swr and no radials
how much power it can tolerate?
With RG58, probably around 300 watts on SSB. If you use RG8-x, it can withstand double or more watts. Using thicker coax such as RG213 with length for 20 meter band, will be very heavy.
What livestream channel is mentioned in here? I’m having a hard time finding it. Thx!
How critical is the number of turns and size of the choke
Built a t2lt for 11m a week ago same design it works very well was surprised 7m of coax and a £25 KIT POLE IT GETS ME FROM THE MIDLANDS INTO EUROPE NO PROBLEM 40WATTTS NEARLY A thousand miles
The 12m and 10m bands have recently sprung into life big time, so I suspect it's the same with the 11m band. Enjoy!
@@paulsengupta971 alot of people have taken there ham licence in lockdown so there has been a resurgence in cb 11m and the ham bands
I was referring to the propagation, but yes, a lot of people have got into it, or got back into it over the past year and a half.
@@paulsengupta971 the reason for that is we are going towards a peak in propagation its should rise two to three years and then die of again
Hi Matt, what amp are you using with the HL2?
You will find that is an upscale version of most 2.4GHz coaxial dipoles inside those plastic covers on your WiFi router :-) The choke (24t on the former) isn't usually critical.
Well, I am having a conversion (imperial to metric) crisis; in that a 68mm diameter does not have an equivalent imperial size. I am looking at either a 60.3mm or a 75.2mm diameter. That translates to a 2" or a 2.5" standard drain pipe. How does that change the number of turns needed to electrically lengthen the antenna? It has to be different doesn't it? I dunno because I am not well versed or learned in Antenna science and lore just yet. I am however, a patient old(er) padawan. Please help me Obi Wan...
If you use a similar amount of wire you'll be fairly close anyway.
I made a VHF/UHF of this type of antenna for 70cm and 144 MHz works well.
I’m new to this and my question is is this antenna for Short Wave listening? If so how did you get that pole erected so high? Thanks!
Nice to see you are getting on well with the HL2.
Maybe you could do a review of that mast too as it looks useful but a bit too expensive for an impulse purchase! The spec suggests it could be used for a medium sized yagi (6m 5ele maybe), presumably when guyed, but don't know how that would pan out in reality?
A vertical half wave dipole it is
Really nice video I’m curious did you do any type of calibration on your analyzer after you got it in the mail or was it ready to go as soon as you received it
Well explained tutorial and demo, thanks. What would you estimate SSB power rating to be for the coax you used?
Probably 300w maybe 400w real world. I think the max rating is close to 600w but you can't run at max.
Nice antenna! Love the Hermès lite 2 footage as well.
Thanks! I’ll have another dedicated HL2 video coming soon regarding amplifiers etc :-)
Would this work as an end-fed horizontal antenna or is it only designed to operate vertically?
I think its designed more for Vertical use. If you need an end fed, look at using a 49:1 transformer
Is your form 60mm OD or ID? I'm trying to figure out an equivalent over here in Canada. All our pipe is in inches. Thx, Brent VA7HUM
World's simplest antenna, just one piece of coax! I don't think I've actually seen anyone do this before but a lot of little Wi-Fi antennas are made this way.
When you trimmed 15cm off, what was the SWR?
Your audio sounds great mate!
Thank dude!
Great idea and brilliant video, just cant afford that mast and would never get it past the QTH Commander!
Why not simply solder a 510cm solid core wire to the centre wire of the coax, and save both money and time?
Do you have any videos on the NanoVNA? Played with the new toy, but no joy. Needs the expert,Matt, to explain it to us all 😁
Thanks Mike, I don’t think I do, not dedicated videos anyhow. I’ll add it to the list! Cheers 😃
QSO from G to ON? That is a local QSO that should be possible on a bit of wet string!
Its a centre fed vertical dipole. So there!!
Firstly, mate 17 meters of coax isn't cheap but neither is that 50' Moonraker pole! Cost more that my G90 that I got on sale. LOL. Since I am not skilled yet in antenna what would it take to do 28.3 to 28.5MHz? That's my lot in HF land until 12 August when I will pass my General and spread my HF wings. Love to build one and report back what happened.
RG58 is probable the cheapest you can get. But please, let us know how you get on! I believe there are plans out there for use on 10m, maybe I will make a video on it..
This is very useful. Is there anything like hf vertical all band antenna with out radials ?
Yep vertical doublet. 25 feet plus for 20-6
@@timg5tm941 thank you Tim. I have subscribed your channel too. As a beginner I am learning from other hams and that makes me feel good.🙂😇
The problem is that to get an efficient antenna on the lower bands, you'd need a very tall insulated pole/mast. While a smaller antenna will work (maybe with a tuner) it might be better to create some sort of inverted V.
How would it work on other bands with a tuner?
It won’t (very well)
Nice one matt. Tim G5TM also made a video on this fairly recently. I believe it wouldn't be too difficult to phase 2 of these for some useful gain & nulling out QRM. I already have have the phasing kit. At most a matching circuit would be needed at the phasing relay box.
Really looking forward to that once Colin - I take it you are looking at quarter wave distance or half wave between them? I might try that for 10m to see the front to back.
@@timg5tm941 I will initially try 1/8th wave then 1/4 wave if the former doesn't work. As Justin explains and as I understand it, the phasing/delay line lengthsbhave a direct realationship to the spacing and not the type of antenna.
Can you make one for 40m
Hiya just found your on RUclips form where your live it's looks like where I used to live could be there same place maybe they same flat
Very cool!
Nothing but the hf version of the famous flower pot vk antenna
what is power capability, can i use it QRO ? over the 500 W. ?
Hi - just my thoughts - confirm the coax cable’s basic power rating for the frequency and then perhaps improve the basic common mode choke if you want to go QRO.
Top vid Matt
Excellent ant for 20m if you cannot fit radials in, I myself use a 5m painters pole with radials, less height not seen as much, and I have just recently added a parasitic reflector, and boy does it work, especially for long distance dx , 10,000k and more.
Thanks 73 zl3xdj
Made one last year does perform pretty good, not much difference between this and a Antron 99.
Had a go at making this today, I only had pipe about 40mm in diameter? SWR was off the scale, I was under the impression it was the number of turns not the diameter. Can you enlighten me please?
Smaller diameter would mean more turns. Not sure how many more, but if you have an analyser it would make life easy.
@@TechMindsOfficial I have a NanoVNA. I'll try a few more turns
Cool, let me know how it goes
@@leybald60 How'd it go??
@@paulkazjack I lost interest and instead made a 14mhz/20m centre fed cage dipole, three lightweight lengths of wire separated by some plastic drainpipe cut into thing slices as spacers. It has a 1:1 balun at the feed point. I've worked a lot of stations worldwide on SSB and FT8 using QRP power of 10 watts. SWR is 1 to 1.1/1.2 across the band due to the increased bandwidth the cage effect gives. No ATU necessary.
its also called a flower pot I have them for 2m 4m and they work ok.
I also made the 4m version, works just as well as a commercial 4m vertical.
What an awesome antenna indeed, Thank You for your review, 73s 😀
Another excellent video my friend
Great video, mini600 is great too. Thanks.
Great stuff , would it make any difference with the quality of the coax ?
Aaron will i am...
Over a short distance, very little difference would be seen... 1/4 mile grotty coax, yes.
Flower Pot Antenna
I try it yesterday , 9 Meter fishing pole but failed it, swr is 2.1 and RX is very bad, i dont know problem
I’ve currently got mine up on a 12M pole and working UK to USA everyday
Nice to see you use the hl2 :)
Can'tget mine to transmit, no rf output even with drivers all up etc nor sure what it is.
Maybe somethong for a video ?
The t2lt is nice and simple.
Made several of them, dedicated monoband antennes alway work good for me.
Hi - sorry it didn’t work for you ! First thought is to check the antenna is not shorted ( an Ohm meter connected to the coax connector should read open circuit).
@@davidw460 found the problem.
😞 Forgotten to Power the watt meter, oeps. Tune gives me 5 to 8 Watt but audio is very distorted and low gain.
Explained why nobody responded on my calls.
Haven't solved that yet must be also configurstion mistake.
Antenna is a 3 band high-endfed no problem with that on my ft950.
I just made this antenna, but instead for 15M and wound the coax around a large ferroid choke. Waiting on the mast to arrive and then I'll be putting it up! I also took Peter G3OJV's suggestion and soldered a solid wire at the end of the coax instead of stripping off all that dialectric.
This looks like a flowerpot antenna I built for 2m when I first got my tech back in 2017...great video and thanks for sharing...I may give this a try sometime. :-D 73 KN4FTT
Will they work horizontal ‽?
Yes, but maybe better to made a classic dipole
What is the software for the analizer and where do you download please ps love the vid thankyou
Im absolutely amazed by how is your SDR Console set to display that high resolution of received signal! Could you make an instuctional video about SDR Console please?
Muito interessante antena bom impedância dela amigo
wonder how it would work in a horizontal configuration?🤔
Same as a horizontal dipole although the weight of the bottom half of the coax might be a tad strong
I wonder if I could make a dual band 20 and 40 meters antenna with this
What is a centimeter in inches?
Its described as a vertical dipole, so one would asume it could be used horizontally? like say a traditional centre fed. This is cheap as chips so defo worth a try.
A common mistake is for people to use the formula 234 / frequency in megahertz for their measurement of both the top and the bottom half, which results in a too Short antenna and an antenna that tunes higher than anticipated.
The reason for this is because End Effect is employed in the formula 234 / frequency in megahertz - ONLY for the top quarter wave since the bottom quarter wave is terminating at a choke.
There will be no End Effect therefore the bottom half should be the full quarter wave or 108 inches for 11m CB use whereas the top half will end up tuning best somewhere around 103 inches for center of the USA 11m CB band.
The same holds true for any other band T2LT.
Could you make a 40 meter version? Mike KJ7GEU
I tell what’s cool about this antenna , no ferrite 😳
I agree ferite is heavy and fragile. These are great for portable along with my 12m spirit of air pole
That is NOT a vertical dipole! Sorry to break the news. To be a VD it needs an element outside the coax for 1/4 wavelength and tied into the shield at the pint where the inner coax element goes up 1/4 wl. I build them this way using the coax shield pulled down around the coax. To do that on lower bands so far intimidates me. I may try it with copper tape though. Some call this a Flower Pot design. It needs no Coils at the bottom.
All i lack here is the 400 pounds for the mast.... And who knows on shipping to TN USA Problems....
IT,S VERTICAL 1/4 NO MORE