Vertical antennas for HF amateur bands, resonant and non-resonant - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 14, 2022, 12:37:24 am
content: I am wondering what would be the best all around solution for a ham with limited outdoor space, going up, perhaps using a fiberglass pole to hold a copper wire up into the air, and feeding it at the bottom. Perhaps with a unun or an autotuner. And using radials.What are your thoughts on all of these variables? I think I am going to start out just with the unun, counterpoise, and vertical wire and see how that goes, If i use a length that isnt resonant on any of the bands I'm be using, I think a unun and a manual antenna tuner should be up to tuning it to an acceptable SWR. Does anybody have any thoughts on this? I have been fooling around with various magnetic elements and wires for HF receive for some time. I want flexibility.

author: bob91343
author_rank: Super Contributor
timestamp: February 14, 2022, 12:44:37 am
content: First of all, a proper counterpoise, say some radials, takes up about the same real estate as a horizontal antenna. It's just that much of it is at ground level. Second, the population of big signals on HF is the realm of horizontal antennas, although there are plenty of four squares and quads.Given all that, there is no reason a good setup using vertical polarization won't perform well. Since the majority of them are ground mounted, that of course limits long distance performance somewhat. After all, most obstacles are at ground level.My own take on it would be to work with one band at a time, and not try to touch all bases at first. (No pun intended.) I am a proponent of horizontal antennas, except for 160 meters where I don't have enough real estate. On that band I load my tower as a vertical with a gamma match. I haven't tried that in a few years but it's on my list of projects.

author: flano
author_rank: Contributor
timestamp: February 14, 2022, 09:37:20 am
content: End fed half wave antennas work quite well. Have a look at these two videos from VK2PRC.I have a built a couple of these and found the FT240-43 core to work well on 10m, 20m, 40m. With this core I did not require any capacitance to be added. I just tuned the length of the wire.For 40m it is a quarter wave so use the same element as you did for 20m but change to the straight thru connection and the counterpoise needs to folded back on itself until the SWR comes down.VK4MWL

author: M0HZH
author_rank: Regular Contributor
timestamp: February 14, 2022, 12:47:44 pm
content: I've laid out 30 radials covering the entire garden (after a year they're completely hidden under grass/dirt) and run a Hustler 6BTV resonant vertical (freestanding). I don't think much better can be done given the limited space and because it's resonant it works well with high power.

author: fourfathom
author_rank: Super Contributor
timestamp: February 14, 2022, 03:44:52 pm
content: If you can get a decent ground or multi-element counterpoise this should work pretty well. On my sailboat I have a non-resonant vertical (the stainless steel backstay, with top and bottom insulators) being fed by an autotuner. It's a decent setup. Of course salt water is a good ground and I have good coupling to the sea -- dry (or even damp) soil is much more lossy so a wire counterpoise is usually preferred.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: February 15, 2022, 06:27:57 am
content: If you have a manual antenna tuner right at the base of the antenna you won't need an unun.An L-match can be good for a wide range of bands.Some sort of remote adjustment is desirable unless you're willing to go outside each time you change band.Especially for the lower HF bands some top loading, even if it's just a couple of horizontal wires can be beneficial.Or even an inverted-L configuration.Here is where I compare a straight vertical compared to an inverted L and a T.

author: tkamiya
author_rank: Super Contributor
timestamp: February 16, 2022, 06:30:41 am
content: Base loaded antennas are typically very lossy. I wouldn't recommend that. You'll also need a pretty good grounding system. UNUN is just an auto-transformer for RF. Using at base of vertical is a wrong application for that. Instead, if I were doing it, I would place an automatic antenna tuner there and be done with it. Be prepared to be disappointed though.The best solution I have found for myself is to make the vertical element itself resonant for frequency of your choice. For 14MHz band, 5 meter or so aluminum pipe would do nicely. Put in at minimum 4 radial wires buried. You can tune it by adjusting the length of the vertical element.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: February 17, 2022, 07:15:32 pm
content: Quote from: tkamiya on February 16, 2022, 06:30:41 amIf you do this I'd suggest getting the base of the antenna high. You want it to be in the clear away from houses and other objects. Radials can be elevated. If you don't then performance can be compromised as I found here.

author: cdev
author_rank: Super Contributor
timestamp: February 18, 2022, 12:06:54 am
content: You're lucky to have the salt water beneath you!Everything I read tells me that the sea helps any kind of HF operation.I think I am going to be able to have a decent height vertical wire and long radials.Quote from: fourfathom on February 14, 2022, 03:44:52 pm

author: cdev
author_rank: Super Contributor
timestamp: February 18, 2022, 12:26:41 am
content: How cool - a portable setup sounds like fun!I see youre using an iron core toroid,I plan on using an FT-240-43 at least for now. I have a 43 material 9:1 unun already in a similar box and that seems to work great as an unun with a 43 foot wire (non resonant) But you are using resonant end fed half waves? So you use an autotransformer wiring scheme and an iron powder core?Interesting. I wonder whether a "Y" in radials nullifies the effect of multiple radials in a tree like configuration. I know the base of the vertical is supposed to be the point where a bunch of radials converge. But Once I get around 20 feet away from where I expect the base of the vertical wire to be a large area opens up that might lend itself to many more radials, going east I have a large wooded area..I have a large wooded area where I liveQuote from: vk3yedotcom on February 17, 2022, 07:15:32 pm

author: Helix70
author_rank: Unknown
timestamp: March 19, 2022, 05:58:55 am
content: I have worked 150 DXCC entities over the last 3 years with this arrangement, using FT-8 and 100W. I use tape measure radials (4-8 depending on laziness), with a 7 metre fibreglass telescopic pole and an SDG-2300 antenna tuner (with common mode choke made from 31 ferrite ring and as many turns as can be wound), so I can use it across the HF bands without changing the wire length.Regards,Josh VK4JNA

author: cdev
author_rank: Super Contributor
timestamp: March 20, 2022, 12:00:50 am
content: @Helix70,Very fine business.. thats great..Music to my ears.. so its not hopeless!That looks like a quite reasonable doable kind of antenna for me too.To start I am going to be using a vertical wire thrown up at the most around ten or twelve meters straight up into a tree.Surrounded by other trees..