Compact, No-Radial, HF Vertical Antenna based on Flagpole Technique | Ham Radio
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- Опубліковано 24 сер 2024
- Here is an interesting project that enables you to produce an efficient, yet short, vertical antenna that requires no radials. The concept and design is discussed by Peter G3OJV. Maybe you can adapt this idea to suit your own particular needs.
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Hi Peter, great video. I'm the president of the Vandenberg Satellite Armature Radio Club (W6AB) and very proud to have John Portune (W6NBC) as a member and our resident technical instructor. At each monthly meeting John amazes us with his vast knowledge of Physics and Ham Radio. We are very lucky to have him in the club. Cheers. John
Many thanks John and regards to all the Club from me.
This is one of the BEST I've seen on this channel. Bravo Peter. I can confirm that feeding the vertical at 1/3 up from ground does work well because the lower end is coupling to ground, making it electrically longer. The balanced line up inside a conduit will have a slight imbalance, but no big deal. The outer sheath acts as a sort of "folded balun". Placing the real 1:1 choke/balun at the input of the tuner is by far the best location for it. The only thing I would add is that any control cables for the ATU also need to be choked, otherwise return currents will pass through them and render the ATU not actually "floating". I have done this with my AH-4 to feed a doublet at the center, and yes it does work well. 73 Peter, and thanks for sharing an excellent discussion. I hope others make and experiment with this design.
Interesting idea - will give it a try. One thing to watch out for when placing a 1:1 choke between radio and remote AMU is that the DC power from the bias tee can pass through to the tuner.
I have been using vertical dipoles for single bands, and as doublets for a couple years now. This is an antenna that is overlooked far too often. I feed mine with twin RG-6 cable, using only the center wire, one per antenna element. RG-6 is very insulated and can be ran parallel to the lower antenna element, down a metal mast, alongside gutters, etc. It eliminates the issue of metal interacting with the RF field of traditional twin line feed. So you can skip the running of the feed line at right angles to the antenna. I still run it to the 4:1 posts on my ATU.
Balanced line inside a conductive tube, is called TWIN-AX. IBM was using this type of cable for digital networking back in the 70's
73 de K1TDG
Interesting - many thanks.
I have a 40 foot spiderbeam pole coming in and I want to try the 2nd idea with a 38 foot wire on it. My thought was to run the ladder line to a 4:1 balun and then the coax inside the house. I like the idea of nought having to mess with radials! Thanks for the video with a great idea!
Good video, thanks Peter. This idea is very interesting as it might be adapted to make a useful multiband portable/field antenna. One thing that occured to me is, if the "flagpole" was next to a wooden fence, the balanced line may be hidden by running it along the fence.... UK hams maybe need to unite - make flagpoles in our gardens a common feature, just like our US friends.😂
Hi Peter, as always a great informative video , i have been using an Aluminium scaffold pole 10m in length as a vertical and am pleased with the results, mounted on my garage isolated from earth with ceramic, fed from an Icom AH 4 mounted inside the garage, i do have copper radials and an earth all terminations hidden under my decking. Can resonate on all bands between 80 and 6m . Ultimate stealth as one of my wife’s friends came round and commented why her washing line was so tall. Regards. Paul G7JVB
Thanks Paul
I love your channel Peter... and this is another really interesting video... got me thinking for sure on how I could use this idea...many thanks, much appreciated.
very similar project... take one 10m fibreglass pole, & a drum of cheap as chips 2mm Al electric fence wire to run a 30' doublet vertically on the pole with the feed coming off the middle at 15'. The same wires that form the elements just bend at the middle then run horizontally at 15' (ie safely above head height) straight to your upstairs house wall next to your upstairs shack. Some plastic spacers every couple of feet keep the 2 feeder wires apart and make it into ladder line. Put a waterproof box on the wall outside the shack window & stick an old KW EZ-match in it that can take balanced feeder straight into it... then just co-ax to the rig inside. Setting the MANUAL atu for each band takes seconds once you have found the settings. Should work 15-80 (10m hits close to a high-Z full wave dipole hence harder to feed but having to have a separate dedicated 10m antenna isn't that much of a problem)..... no co-ax trip hazard trying to take a base/ground co-ax across the grass, over the concrete path then up through the house to get to the shack... not only will the fence wire budgie ladder be shorter than the ground routed co-ax alternative but ladder line tends to be lower loss than co-ax per metre as well (even "home brew" like this). In an ideal world if you can arrange it so that the ladder line is 33' long (a nice shack to antenna distance anyway) then that is a half wave on 20m so even though the ladder line will be about 600 ohm you should still get an easy 75ohm at the antenna side of the ATU on 20m... not essential but a nice little Brucie bonus as half wave long lines reflect the impedance at one end at the other making 20m even easier. The ATU handles all the other bands anyway (& 20m even if not half wave feeder).
If you really want to be cheapskate... forger the external waterproof box for the balanced ATU.... if your double glazing is plastic framed you can sometimes get the 2mm budgie ladder wires to pass through the window jam directly to have the ATU on the internal window ledge (just watch out if it is raining & you want to run high power & water gets around the jam to bridge the wires).
Interesting stuff. But remember that the 10m high Z is of no consequence as the matching takes place at the end of the balanced line. Also, many hams prefer to use coax for the primary feed for convenience or for low profile apperance.
On the to do list..Thanks Peter
A cellphone company did this. Right next to our complex. It took most awhile to catch on. It is attached to a big box at it's base. Some think it's a Stingray. But we do know it's an antenna..
This is HF. The cell phones operate from 800 MHz up to 5 GHz
Very interesting. I wish I was closer to your store. USA here.
Thanks Peter. Interesting stuff OB!
Hi Peter - A GREAT video - I really enjoyed your explanation and how easy it is to build - I am sure you will encourage your subscribers to have a go especially as it covers so many bands - excellent -Dave
Thanks Dave, particularly as you gave me the link!
Another great idea Peter...73, Bill, W6QR
A very interesting topic and an extremely well delivered presentation.
Thank you Peter.
M0DSK
I've been studying the "flagpole" antenna made with the ladder line inside the flagpole. The company that makes them has a somewhat high price point. Although with some packages you get the antenna tuner, and various other items. I'd say about $1400 out the door (minus tax) is a good combination and free shipping in the states. Had another flagpole with the radials and used the pole as an antenna, along with an antenna tuner.
But sold that and moved on. Now, I'm actually considering this expensive one, with no radials. I live in an HOA and a 20' flag pole is ok in the colony.
I was hoping that you'd have a flagpole with the ladder line and tuner, to demonstrate to all of us here on this video.
73's de KQ1K
This looks like an off center fed but vertical. The balance line could act like part of the matching network depending on length. The tuner is making the match.
I'm guessing the return currents get to ride on the bottom short piece of wire. Same idea as adding a ground side to the End Fed half wave for improved performance.
Great video. The only slight fly in the ointment is that the LDG remote ATU are quite pricey at about $299USD. Sort of takes the system out of the inexpensive category for many beginners.
Yes that is true, but I think similar items from other manufacturers are similar in price.
Hi Peter, another excellent video. May I ask you were you bought the bamboo stand that is sitting over your two radios? Look fantastic!
I bought the 20' version of the Flagpole antenna and used it with the RT-100 and 1:1 choke but never got good performance out of it. I'm in mid-US and could only get to western Europe. I corresponded with John many times and although he was very helpful the best we could do was mid Europe after putting down 32 radials which were not connected to the antenna but merely acted to increase soil conductivity. One of the problems with this antenna is hiding the remote tuners esp. if you don't want to bury it in the ground. I used a planter box but still you could tell something was fishy and it didn't fool my more curious neighbors. Interesting concept though
I took a 8 inch pvc pipe and put noaa and skywarn stickers on it, slapped an old wind meter at the top of the 30' plus antenna nested inside the big well decorated pvc pipe. Everyone assumed it was a weather station and accepted it. 😂
Ia there any actual measurements of the balance in any of these systems ?
When you use the term “garden” is that referring to a small yard in the uk?
Cheers Peter, very interesting, will turn my doublet 90ds at the weekend.. loving my new Zero QRM /!QTH from IO66 Inner Hebrides!! Regularly RX ..YB, VK and RA0 on 15ms, 10 still to come alive like last October 73 , Mm0hlt
Yes I spent a week in Hebrides and another in Shetland. Plugging the antenna in made little difference to rx noise. Problem was I could hear stations that could not hear me because of their local noise!
So interesting & tnx! 73 de WA4ELW in TN 🇺🇸 dit dit 😃
This is very interesting however knowing that the ATU's require DC to operate and this is supplied down the coax. Having reviewed the video you referenced, I use an SDG tuner that requires the use of an iso-T to strip off DC from the signal in the coax. The type of balun needed is a 1:1 CURRENT BALUN. So one needs to install the system as such, current balun, iso-T, tuner and antenna. What does one do for lightning protection at the antenna point? Can we use a spark gap lighting protector at the point where the ladder line meets the tuner? When not in use I keep all antennas isolated (disconnected) from my equipment. Dropping a flag pole is out of the question as to the fact it would arise suspicion why it’s lowered for t-storms. We live in a "hot zone" for lightning strikes being up hill and near the ocean.
very interesting video
GREAT video Peter. What would your thought be on elevating the flagpole antenna approximately 25 feet or so. Since it does not require a ground there shouldnt be a problem? Please let me know what you think. Thanks again for the awesome video Very well presented.
Jerry
Very informative video and fascinating antenna design! It's potentially a stealth antenna as well, though I believe my XYL would have noticed if a 7 meters tall pole popped up in the garden.
How would this antenna work if you substituted the tubing with wires? I assume it would work, but most likely at the cost of the bandwidth.
It would definitely be interesting to build and experiment with.
A bit like a ZS6BKW turned on it's side.
I have recently purchased a 20' Greyline Flagpole antenna and the LDG remote tuner sold by them but have not had a chance to install it. Hopefully, I'll get it completed in the next month or so. However, I have a question after watching your video (very well done by the way!). I still need to purchase a lightning arrestor and am considering getting one that has ladder line input and a coax output to the LDG tuner. Any suggestions for another solution or configuration would be appreciated.
hello Peter Love your videos, i have just started my foundation course and don,t have much money the video about a year ago that you did LOW COST HIGH PERFORMANCE HF ANTENNA is a real gem. My question is would a slightly smaller ferrite ring still work and insulated copper wire as I have both.
Brilliant I have a home made ZL6BKW, I will have a go with my 300 Ohms Ladder-line and the 10m pole and use my LDG 4:1 I use my 10m pole for my EFHW 33ft up, Brilliant video how much wire do I need both side 20m in total Thanks Tom 2E1FUE 73's.
Excellent video but would it not be just as easy when attaching the atu to the doublet just to use a short piece of coax the centre to top doublet and braid to bottom as your using short piece coax to go to balan oviously using pl259s to plug into atu or is there specific reason for connecting doublet directly to atu just wondering
Hello Peter
I have an SGC 230 coupler/tuner.
I'm very interested in making this antenna, however putting the 1:1 balun very close to the SGC 230 isn't possible due to the SGC having a 10ft piece of coax pre-fitted to the input side. Would it matter that the balun is this far away?
Would the SGC 230 even need a balun as the manual seems to intimate that baluns aren't needed with the SGC 230?
Thanks for the great videos by-the-way. 🙂
I have used the SG-230 and would be inclined to miss out the balun and use it as intended. It works well even with quite short elements.
WOW! You replied! I'm very honoured.😊
I appreciate you taking the time to make these videos.
Living in council property and surrounded by neighbours means my antennas have to be a little unobtrusive. I'm sure I could get away with this one.
Hopefully it's decent on 10m as my current antenna (GM0ONX Inverted L) doesn't work well on that band.
Appreciate the reply!! 🙂
Looks like a Valve (tube) amplifier back there - what tube(s) are in it ?
Hi Peter, your video is very usefull and informative. One question for the 1:1 balun, is this used only to stop common mode currents flowing to the shack or is it for impeadance matching?
I would say the former. The BALUN is stopping common mode current on co-ax, no impedance matching (aka impedance transformation). Impedance transformation in this set up will be carried out by a combination of the balanced feeder and AMU.
Could you then run the wire out horizontally from the top of the fibreglass pole across your garden, forming a sort of inverted L? How would it affect the impedance at the feed point, would it be higher as you're now further from the centre towards the end of the wire? Would it still work as a doublet?
Like many things in ham radio, the answer is try it and see!
Where is the link ? I dont see it.
Never seen that balanced antenna line sold in my country. There is coax everywhere in the shops, I wish people stopped doing projects with that ladderline thing, that is not a thing in many places ... :(
Not sure how a TWENTY foot doublet, however centre or off centre fed, could be efficient on 40, let alone 80m! 🤣🤣🤣 By the way, the video you mentioned was made by an antenna company with, shall we say, mixed reviews on their customer service.
You are missing the point. completely. The task was to compare efficiency for a given length by changing configuration.
Your video has been quite enlightening to say the least, so I'll return the favor with a small tidbit. Most antenna modeling software or NEC software (Numerical Electromagnetics Code) is pretty _complicated_ stuff for just your average person to figure out and use, right? So Roy Lewellan, W7EL created his _own_ version of _"EASY"_ NEC software! Hence he named his creation "EZ"-NEC (as in "easy neck")... 😉
73 DE K7AEK
Yes I used that many years ago and met Roy in Dayton.
Might be able to use a 9:1 balun to match to the 450 ohm window line. Come to think of it, just mount a 9:1 balun right on the antenna with a 1:1 choke and feed it with just coax. This looks familiar, cant remember the name of it.
The essential is a good match not a compromise.
try it you will be surprised@@watersstanton
you miss the 4:1
Wrap that up in fibreglass and sell it.
Yes, without any doubt whatsoever, u DO promote ideas, which was the main reason I subscribed to ur channel long ago! Tnx agn...de WA4ELW in TN 🇺🇸😀
Thanks for your support.