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!?

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

Do you recall which one or what article?

Exactly what i use for POTA

That’s great news! Better satisfaction knowing you made it yourself too! Cheers

Could you send me the plans for them all I would definitely appreciate it very much. My name is William Peacock AE4OY .73

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.

You’re welcome 😉

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.

Thank you for sharing this information 🙏

A Dipole is not end fed. Di Pole..... End fed is a monopole

​​@@juststeve7665no 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."

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 :)

Thanks! I’ll have another dedicated HL2 video coming soon regarding amplifiers etc :-)

Google "coax choke balun" or "Ugly balun". There are designs out there.

Thank dude!

Probably 300w maybe 400w real world. I think the max rating is close to 600w but you can't run at max.

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 🤣

Awesome! Don’t believe it’s directional, so possibly band conditions depending on your location. Good job!

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

lol the antenna doesn't get you there... Ionospheric propagation does. Literally any functional antenna will do this

Think I just taped it to the top of the pole using electrical tape.

I think its designed more for Vertical use. If you need an end fed, look at using a 49:1 transformer

Thanks Mike, I don’t think I do, not dedicated videos anyhow. I’ll add it to the list! Cheers 😃

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..

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.

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.

It won’t (very well)

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.

If you use a similar amount of wire you'll be fairly close anyway.

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.

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.

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.

Aaron will i am... Over a short distance, very little difference would be seen... 1/4 mile grotty coax, yes.

I also made the 4m version, works just as well as a commercial 4m vertical.

I’ve currently got mine up on a 12M pole and working UK to USA everyday

Yes, but maybe better to made a classic dipole

Same as a horizontal dipole although the weight of the bottom half of the coax might be a tad strong

The same holds true for any other band T2LT.

I agree ferite is heavy and fragile. These are great for portable along with my 12m spirit of air pole