Build an EASY 6 Meter (50 MHz) Vertical Antenna (Using just RG-58!)
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- เผยแพร่เมื่อ 3 ก.ค. 2024
- This is a really simple and easy to construct antenna that will get you on the air on the six meter band using only RG-58 coax!
I needed a quick and simple antenna for my WSPR beacon over the summer season. Enter the coaxial dipole or aka flowerpot antenna!
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This simple antenna was described by Bill Orr, W6SAI back in 1959 in his book "S-9 Signals,
Inexpensive antennas for the radio amateur." He described it as the "Cobra" antenna due
to it's coiled decoupling choke at the base of the radiating portion. I built a few for 10 and 6 meters. Nice to have it "rediscovered."
I am new in to 6 meters and seen your video. I build it with RG8X to your specifications and i have a 1to1 SWR on 50.145 Mhz. Can't wait to try it out in the morning when the band opens up. Thank you for this great video.
Glad to hear you got a good SWR result Terrell! GL hope you work a few on air
! only have a piece of RG8X, I can use this without modifications to this design?
Thanks, I'm a noob, have a IC7300 w no 6m antenna.
@@elconquistador932 did you make it?
Love it , been using coax antennas since 1979 as a kid on Am cb.
LOVBE THE ADAPTER CONECTORS IN BACKGROUND, SWEET VIDEO, TODAY I BUILT TWO ANTENNAS FOR UHF
Thanks for sharing. Great video! Just made one of these yesterday in La Pine Oregon USA. Going to put it to the test with a Nano VNA today. I'm a new entry class ham (technician) KJ7VUL.
I am definitly going to try this. Was going to modify the 10 meter dipole i made to make a fan dipole, but this looks like a lot of fun!!. Nice little 9 foot vertical
I made one of these for 2m as a SOTA antenna, after seeing it described in the RSGB yearbook. Excellent results on 2m mounted on a Sotabeams 7000HDS pole. I must try a 6m version!
We used to call this a coaxial antenna, widely used for "mobile telephone" service before cellular phones made that service obsolete. We used to see those mounted on limousines, with a chrome plated tube forming the lower quarter-wave section and a whip antennas as the upper quarter-wave section. This seems an easy way to make one. It should work well on 2m too. Nice approach! ~ de ND1L
@Conner Alexzander ...which has what to do with antennas? Or are you advertising something?
Good on you Hayden! Cheers
Veru useful & simple antenna, especially as we come into summer here in VK. Nice!
Wow i made one of these today and absolutely amazed at the performance. Ran mine up a 10m squid pole and worked perfectly. Looking forward to seeing what you do with the 10m version. Thanks very much for the info. VK2TEK
Glad to hear it works!
It’s not an end fed dipole it is actually a centre fed dipole. The feedpoint is where the removal of the shield starts. Signal comes up the inside of the shield and goes back down the outside of the shield and is stopped by the choke.
Hayden, perfect timing young man. I just upgraded my coax on the shack so I'll buils at least one of these. I will also build a 6m yagi and point it towards VK this summer. Keep up the great content.
Thank you Jose, good stuff mate
I did one of these in the late 80's but I can't for the life of me remember how well it worked.
Great Antenna Thanks. I built one this morning, with measurements bare coax 1330mm, shielded coax 1295mm and 14 turns of coax on 50mm pvc. I mounted it about 500 mm above my flat roof. 1:1.2 from 50MHz to 52.9Mhz
Nice work!
Wow I can’t believe you posted this. I’ve been planning on building one of these. I can’t find RG58 (without aluminum shield anywhere) and will be trying this with RG8 this evening!
Please let us know in the comments how the build went
Waiting, looking forward to your video.
Nice work. Thanks and 73
I've made one for TV, works fine
#MNHR
Team replay for the win!
Six meters, the magic band!
Cool build mate. Keep it up.
Hi Hayden, i came across this video on a search for a coaxial dipole for 6m and decided to make one up with your measurements which were spot on. Flat SWR throughout. It's E season up here so looking forward to making a few contacts on the magic band. 73, Sid MI5UTC
Thanks Sid and glad to see you're getting some good results. Good luck with the DX over E's season
Just built one after watching this video. Band is not open at the moment but the SWR is great.
Just made this and works well.. used 13 and half turns and is all good no RF in the shack... Silicon seal tube for a 50mm coil...did the job.
Nice! How's it performing?
@@HamRadioDX Working really well. Strong locally in East Yorks area and DX into Germany and Italy on the first test out..
Hi so it's 2023 March 26. I found your video and started to measure and cut some old rg56 laying around. Thanks and I hope I get good RX.
I have one for Marine VHF I built. I did not put in a choke, it still works fine.
HAM radio is fun. :-). Thanks VK7HH!!
Made one for 4m and a duel band 2m 70 cm 4m works extremely well the duel band as an swr of 1.2 across both bands but i haven't tried it yet. It could be a 5ft dummy load
Well, I know this is an old video, but I stumbled across it, and boom, in one day (after some part scrounging) I have a 6 meter antenna! Used 1 1/2 inch ID PVC for the base and coil wrap with a pvc reducer to 3/4 for the vertical mast. VSWR of 1.5 at 52.4 MHz (13 wraps). Total cost less than $30. Great. Thanks. Subscribed. W8ISM
Nice work! Good stuff, 6m has been open the past week or so.
You can use a lot less coax if you make the unshielded part using a piece of insulated wire.
Yep
Nice Video 👍. Greetings From Belgium 73 .
Thanks Hayden.
Good to see it performs favorably against a commercially made product.
I know Im asking the wrong place but does anyone know of a way to log back into an instagram account..?
I was dumb lost my account password. I would appreciate any tips you can offer me.
@Brodie Moshe Instablaster ;)
@Gatlin Francis Thanks for your reply. I got to the site through google and im in the hacking process now.
Looks like it's gonna take quite some time so I will get back to you later when my account password hopefully is recovered.
@Gatlin Francis it worked and I now got access to my account again. Im so happy:D
Thanks so much you really help me out!
@Brodie Moshe Glad I could help :D
I've made flowerpots for 2, 4, 6metres plus dual banded the 2metre one with 70cms, All excellent performers. Up to 40miles range indoors at ground level on 2 and 4metres. Not tested my 6metre on yet. But nice build. 73 de GØUSL
Flowerpots are great…I built one for 2 meters and one for 6 meters. They both work great. I don’t bother with the long pvc tube just use a short piece for the choke coil and just hang the wire with a bit of shrink over the point the braid ends to keep water out.
Hi Hayden VK7DG, I built one a few years ago for 6metres and instead of cutting off the coax shield I folded the shield back over the lower 1/4 wave with the insulation on it. This gave a flatter SWR across the band. I used a smaller coil former for the choke to fit the fibreglass pole I was using. Cheers and good stuff.
Thanks Dale, that’s something to think about an experiment with! I was going to do another one, and maybe one for 10m to have a play so I’ll try that, thanks. Did you put heatshrink or something over the braid to keep the water out?
Hello from San Francisco, CA
Centre Fed Coax Dipole. Built several of these for 6m and mostly 2m. The lower half is shorter because of the 'fatter' element size, not velocity factor. Another way to have even less chance of radiation back down the coax, is to actually fold the braid from the top section back down over it's self on the outside. This does however mean that it will be exposed to the elements, but If it's housed within a PVC pipe it doesn't really matter. the VSWR can be lowered by tweaking the turn count of the choke using a VNA.
I made a 6M flower pot antenna and first ever contact was 5/9 into ZL. 50.110. VK3DJC
Nice!
I need a 6m portable antenna. I found your video and built it with your dimensions, except with RG-8/X and not with RG-58. The SWR is 1:1.04 at 50.180 MHz. Great and thanks for the video.
Awesome mate!
Nice................................
Have you ever tried the coaxial 'sleeve' antenna? This is where you peel the braid of the radiator back over itself, becoming the other leg of the dipole making it a center fed dipole. would love to see a comparison.
Thank you for the video!
Surely you jest. Let me know how it turns out for you, will you?
Its actually a centre fed. Not an end fed !
Cool
Other people near your QTH will hear you pretty well with a simple 1-3dB antenna on 6m.
Look a bit further to find that there are stations using it to DX.
I wantedto see this but the video won't appear. i'll just build a dipole. Works pretty good
I would have liked to see you adjust this antenna to get a better match. Sure it's ok and you might use a tuner, but some of us want to use it on the SSB range Nd won't know how to tune it. Do you cut or extend the top, or do you add or remove a turn like many suggest? Left wanting more info Cheers
Thanks Haydn. How do you get the choke so nicely fitting around the pole ? are there spacers inside ? Thanks
Just a quick PS -- I DID strip the foil shield off when I stripped the braid on the top section. But it's still there in the rest of the coax. Thank you.
Excellent video. I will build one of these this winter. For SWR purposes, do you have any idea of the length adjustment to make if I want to house this in a 3/4 inch diameter pvc pipe rated at 480 psi (standard thickness)? Thanks
Not sure about the exact length adjustment putting it in a radome. But I'd start off by making it slightly longer than you need, and then trimming from there.
I have an 8 metre squid pole with a choke at the bottom for HF. Question? Would it be feaseable to parallel the 6m ant to this, ? Thanks.
Yes, the vertical bazooka antenna works great. One reason for this is it's a 1/2 wave dipole, no radials to push the pattern up towards the sky, so the radiation angle is zero, flat to the horizon. Back in the 1970s, I used to sell and service equipment for CBers during the CB-craze. The best performing antenna back then was Shakespeare's "Big Stick", which was exactly this antenna, just constructed a little differently to form a 17 foot tall self-supporting pole.
Thanks for working out the numbers for me. ;-) I came here because I need to throw together a makeshift antenna for 6 meters and this will be it.
Foam slows the signal a bit- velocity factor
Hi, great content, that aside, My first name's pretty uncommon in UK, the only other person I've heard with your name that I can remember (or similar sounding, different spelling), is a hologram in Star Trek Voyager, who was a leader of a hologram crew in "Flesh and blood" - Cool Name bro! :)
What are the imperial measurments. I have no way to measure metric.
Love your videos, just what I need for somebody who is not very Technical. 73 De ZS5DG in South Africa.
Thanks again Daniel
Hi Hayden, now we need to make it into a co linear and stack on more top elements.. : -)
Although I can contact some people others 1 mile away from the others I can hear can’t hear me nor I them. Is it the vertical horizontal issue?
Can something similar be built out of rg6u or rg11u? If thats what you have on hand?
Great simple antenna design. How many watts can be run with this type of antenna?
I guess the rating of the cable at the frequency that it's being operated on? I don't have enough power to test :D
Can it be mounted on alum
pole??
Nice! I might make one of these, if I can get my hands on a pole. Whats the gain on one of these?
As it's just a basic vertical dipole, there is no free space gain as such. You could probably space it away from another pole used as a reflector to get some gain in a certain direction however
Can be use rg59 or rg6 for vertical VHF antenna?
9 30 anten swich home made please
I know this is a 2 year old video; however, I recently fell upon this and another one you did with this form of antenna. I have a question on the need for chokes, grounding, etc. Is a choke required or does the windings act for this purpose. Is it required to provide a ground system for this antenna if it is not used as a permanent install...only erected for use and taken down.
Thanks!
Hey mate, the choke is the coiled coax. It appears as a high impedance on the outer shield of the coax to stop common mode currents from flowing on it, back down to the transmitter. It’s pretty critical to get the correct turns/diameter otherwise the coil wont provide a high enough choke impedance. No need for a ground
How long is your rg58 feeder to the antenna? Line loss on 6 meters can be substantial. Loss is on the order of 2.7 dB per 100 feet. 100 watts in nets about 53 watts at the antenna end with the rest heating the coax. It affects receiving signals too. What kind of coax is on your Diamond antenna too? It is strange that you get such good signal on the homemade antenna and no signal on the Diamond. Coax or connector trouble?
Feeder is about 30 feet. Diamond antenna uses low loss LMR-240, same length.
How is this a dipole when it's using the full coax as part of the half wave? Wouldn't in theory the full coax cancel out the magnetic field? I know that the rf will ride back down the shield but wouldn't it be more effective if there was an additional conductor attached to the shield that folded back on itself? I'm new so sorry if this is a dumb question.
No. Skin effect gives effectively two conductors. One conductor is the inside of the shield with current flowing in one direction and the other is the outside of the shield with current flowing in the opposite direction.
1376mm is 54.17"
Would RG11 work?
How critical is the coil to the overall tuning and performance of the antenna? I have a T2LT that I made for 10m and no longer need. It can be easily cut down to length for 6m but the coil is 16turns on a 68mm former. Do I need to change it or is the coil less important?
Yes you will need to change the coil as the impedance of the choke will change. You’ll basically need less turns, so just unravel a few until you get the proper amount and run that extra cable back down into the shack
What calculator or formula did you use to get the lengths of each leg???
nomonsuhendar.blogspot.com/2020/12/flower-pot-antenna-calculator.html
this might help. gust google the vf of the coax you want to use.
I thought the idea behind coax was to keep the signal in ?? In theory it doesn't seem like it should make a good antenna. What am I missing??
..looks like your using RG 58 for the long feedlines... that stuff has 3.3db loss @ 50mhz (over half your power and received signal) If you can get some LMR 400 it would make a big difference. Buying a new FT891, best value in ham radio... and lo but it has a 50mhz bonus..my 80-10 EFHW does not work on 6, so this is a cheap n nasty option.. tnx Hayden Richard VA7AA
This does not appear to need a ground plane. Correct? Regards
Correct, a ground plane/counterpoise would mess up the VSWR as a dipole, even an end-fed doesn't need a ground plane/counterpoise.
Show How To Make Antena For 1 Meter Or 2 Meter Band
1 meter???
Wow! I've now got a new dummy load. I made one and VSWR is 1.1-1.3 across the band. Length of exposed top 1,350 mm and bottom 1255mm. It will not be enclosed; it's a roll up to pack. The only modifications is that I formed an eye at the end to make it easy to hang. That effectively reduced the length by about 3/4". The other is that I used a disposable water bottle with a 2&3/8" diameter with 13 turns. Before making it I also calculated the feed line length to be virtually invisible using the VF of .66 before I cut it. All this paid off that I didn't have to trim it to get what I think is perfect. Hung it in a tree once. Now, if only I could get one QSO.🙄 I bought 100' RG58/U with BNC connectors for $18, so what I used cost $8. It has an adhesive backed foil that peeled off easily. Did your VSWR go up or down when you enclosed it in the PVC tube?😏
How much power loss do you estimate that your loosing with the impedence down in the low 40's?
Google “mismatch loss calculator”. Even with a 3:1 SWR you’ll lose only 1.25dB of your power. With 40 ohms purely resistive and no reactance, SWR is about 1:25:1. In other words - not much at all
9.28 the diamond antenna has an incorrect connection. the cable must exit strictly in the center of the branch pipe.
Huh, really? I mean, mine is like that anyway.... but.... would it really effect performance that much???
@@anonyninja7737 this is part of the symmetry. Helps from the leakage of RF currents on the outer part of the braid
I'm a Newby at this stuff so please be patient with me. I built the antenna to your specs, but it was resonating at about 48 mhz and swr wouldn't go below 1.7. I tried shortening both lengths proportionately, and the darned thing won't resonate at all! Two questions: First, the RG58 I used had a foil shield inside the braid. Is this causing a problem? Second, in America I couldn't get a 50mm coil form, so I used the best I could find -- a 2inch pvc pipe. Needless to say it's close but not the same diameter. Is this causing a problem? If neither of these things is causing a problem, what do I do now? Thank you.
Hey mate,
Couple of things - the RG-58 with a foil shield might have a different velocity factor, so the lengths may be a little different. You're right though, shortening the elements should have brought the frequency up. Where did you get it to resonate after you shortened it?
2 inch PVC pipe is fine. Maybe see if you can find another bit of RG-58 to try?
Thanks so much for responding. When I shortened it, it wouldn't resonate acceptably anywhere. I think I'm going to find a hunk of RG-58 without the foil.
You must have missed this. Peel the foil off. I did and VSWR is 1.1-1.3 across the band.
I built one and it worked well as far as SWR. I didn't have 50mm PVC so I used 40mm electrical conduit and added a few extra turns of coax. Measuring to an exact millimeter is rather difficult. I just got as close as I could. It appears to be very non-critical. SWR bandwidth seems very wide. Now I would like to determine if this can be scaled up to 17 meters. I wonder how many turns on what diameter to use for an RF coke for 17? All I can due is experiment. Thanks for your video.
There might be a bit of extra info in this video - check the description for a link to turns on different former sizes too. Cheers! th-cam.com/video/GCubZoD25tc/w-d-xo.html
@@HamRadioDX yeah. Quite a bit of chatter that had nothing to do with half wave verticals. One thing I'm truly curious about: how did you arrive at these dimensions? A quarter wave at 50.5 MHz is 1411mm. Allowing for velocity factor if indeed that applies (66% for RG58A) would give 931 mm. So where did 1346 and 1376 come from? Just experimentation?
@@1dxvictor the dimensions were scaled from the VK2ZOI experimentations. Just tried it until it worked
@@HamRadioDX OK. You got me. I can't find any mathematical approach that results in your dimensions. Most methods come out with values quite a bit smaller than what you have. Trying to scale this to 10 meters will be interesting!
@@1dxvictor .66 is VF inside the coax, not for current flowing on outside.
Is this just for FM or does it work for SSB as well?
Works for both SSB and FM 👍
Another question, what is the furthest you have reached out with this antenna?
May be a silly question but .. why is the top 1/4 a different length to the bottom 1/4 ?
Velocity factor of the coax (bottom half) makes it slightly shorter
@@HamRadioDX I still can't see how you arrived at these figures, even taking into account the velocity factor if your target freq was 50.3Mhz. Were you rounding off the numbers or did you change the target freq you mentioned in the video.
Sorry if I'm being a pain, I'm a bit new to this and my calc's don't come up with the same numbers.
Are the final numbers you have shown been AFTER trimming to achieve a decent SWR?
I've worked on 299.79/50.3Mhz and a velocity factor of .95
Another stupid question ... why does the velocity factor only affect one side of the antenna?
Why is a ground not needed?
The antenna is a half-wave antenna which does not require a ground.
Thanks Hayden, I just put a new Bushcomm swc100 up after lightning strike blew last one apart. Surprisingly, the old antenna had a SWR of 1.2 on 52.525? New one is SWR 3.8. However the 7300 tuner can get it down to 1.2. Have had a chat on 53.825 repeater with good reports. How much damage am I going to do???? Should I attempt to build this antenna for 52-54Mhz. Cheers and thanks. Don VK7LDH.
Hey Don, the new one you put up, is that tuned for the bottom end of 6? You won’t do any damage if you use the tuner to keep the SWR down. I do it with my 6m vertical, it’s tuned for the bottom end of 6, but if I want to use the FM repeaters I use the tuner as it’s above 2:5 up at 52.5 MHz. Hope that helps, be good to chat on the repeater soon too 👍 can you get into 53.700 repeater?
@@HamRadioDX the antenna is only tuned for 80 - 10 metres. That is why I and Bushcomm were surprised with 6m. Yes, I get I to 53.700 (Kaoota). It would be good to catch up on there sometime. Thanks for your answer. Without 7300 tuner, the entire 50-54 is over SWR 3. Tuner brings it down though. Cheers.
No worries yeah if tuner tunes it down and it gets in all good 👍 catch you on the air soon
@@HamRadioDX I will call on it more often. I also get into the 10m on 29.680. Both usually quiet I find. Like now :)
Cool, 29.680 is offline at the moment, on the to-do list to fix!
Uhm, wouldn’t it be a normal centre fed dipole if you just took the jacket and turned it downwards along the cable instead of cutting it off?
No, then it becomes a sleeve dipole, still and end-fed antenna.
Thanks for the build and demonstration, but I must chime in that it would be a more accurate test if each antenna had the same feedline.
The coax antenna had RG-58 as the feedline, probably about 5 metres. The Diamond has LMR-240 which is lower loss but about 10 metres. At 50 MHz the loss difference would be within 1dB.
Anyone tried putting radials on this antenna ?
I'm thinking about giving it a go with 4 X 1.4m radials at the feed point just below the coil.
its actually a dipole, radials will give you bad results im afraid.
Duh, I'm so confused🙃
Doesn't seem right. This says a 1/4 wave (top section) is 48.5" yet a 1/4 wave is actually 56".
Does that include velocity factor?
The fundamental design issue with this type of antenna is that the choke (coiled coax) is at the end of the lower dipole element, which is a point of maximum voltage and thus minimum current. Chokes are magnetic components and thus work on current. So it's not the ideal location to place a choke; it can't possibly be highly effective at the location. This is not to say that it wouldn't work as an antenna; stray currents on the coax can radiate too.
The coaxial or sleeve antenna, where the lower element has its own hollow element with a true end (open circuit) at the bottom end is fundamentally a better design (at least theoretically). Note the distinction in that this form of antenna uses the outside of the coaxial cable shield as the lower dipole element, as opposed to coaxial or sleeve antenna that actually has a distinct lower dipole element that is hollow, with the feedline run up and into it.
Acknowledge in advance that this is a nitpick. I just don't see anyone else pointing out the current minima at the choke location. 🙂
Try making one. I did.