HF receiving antenna DIY that can later be used to transmit

[scan_madison]

Hello all,

Been thinking about constructing a plain vanilla dipole antenna using copper wire. I am interested in 20-meter band. Eventually, I want to use the same antenna for transmitting as well once I get the amateur license. Someone told me to get balun. I did some readings on it and I am a little confused.

Would I save money just by buying balun instead of making one? I know balun is simply made from toroid coil. If I do make one, the only problem is it won't be waterproof and may not handle high power when transmitting. But some readymade ones like Unadilla and MFJ costs upwards of $30.

Any tips would be greatly appreciated. Thanks in advance.

 

[Boombox]

Hello all,

Been thinking about constructing a plain vanilla dipole antenna using copper wire. I am interested in 20-meter band. Eventually, I want to use the same antenna for transmitting as well once I get the amateur license. Someone told me to get balun. I did some readings on it and I am a little confused.

Would I save money just by buying balun instead of making one? I know balun is simply made from toroid coil. If I do make one, the only problem is it won't be waterproof and may not handle high power when transmitting. But some readymade ones like Unadilla and MFJ costs upwards of $30.

Any tips would be greatly appreciated. Thanks in advance.

You don't *need* a balun. I have several older DIY antenna books that describe building a half-wave dipole with no mention of a balun. I built a dipole for transmit on CB a long time ago and it worked great without one. So a dipole *can* work without one.

But you will get a lot of suggestions here to use one. If you can build or buy one, it's probably worth it, especially in these poor propagation conditions -- you need all the antenna help you can get to receive, as well as transmit. And a balun probably is a good idea for transmitting, as matching an antenna to a radio is more important in transmitting than it is in receiving.

 

[WA8ZTZ]

If you want something quick, easy, and inexpensive... just build a dipole cut for 20 meters. You will still hear all kinds of HF stuff with it while waiting for your license. Forget about the balun for now. Way back when, nobody used baluns or even knew what they were.

Are there better ways to go... yes, but if you want quick, simple, and cheap then a simple 20 meter dipole is about as easy as it gets.

 

[majoco]

Forget about the balun for now. Way back when, nobody used baluns or even knew what they were.

True, but they didn't use coaxial cable either. They used 'ladder line' which could be homemade too and it was fed from the 'balanced' output of their homebrew transmitter from antenna coupler final stage. The 'ladder line' became part of the antenna, the 'tuner' was part of the transmitter, high VSWRs on the feedline were no problems as the spacing of the 'ladder' was 4inches or more.

A receiver won't care, but it won't give the best results. But if you want to transmit, and you want to use coax cable to feed your antenna, then you need a balun to feed a true dipole because a dipole is "balanced" and the coax is "unbalanced" - otherwise you will get RF power down the outside of the coax cable and into the wiring of your house.

 

[nanZor]

Put up your 20m horizontal SWL dipole *without* worrying about a balun for now. Listen to it, and enjoy your handiwork for awhile to establish a baseline of performance.

Without the balun, the coax braid becomes part of the antenna, and you won't have textbook-perfect antenna patterns, so that you will have a little bit of a vertical component to it.

This somewhat "mixed mode" directional pattern may be a good thing - or maybe not!

If you suffer from localized noise, much of it can come from say within the shack, traveling up the braid, and then back down into the receiver - so many swl's and amateurs like to put a balun at the feedpoint.

The basic function of the balun, is an attempt to attenuate any signals that may be traveling up or down the braid, and make both sides of the dipole equal in performance.

The balun in this case is also referred to as a 1:1 balun, or an RF-choke, which is basically the same thing. I think you get the picture and yes, you can easily construct one of your own. Plenty of articles that I"m sure you are aware of already.

So go ahead, like WA8ZTZ advises and put up the simple dipole. Then *if you feel you need one* install a balun / choke like majoco advises.

But foremost, KEEP IT FUN. Work your way up the performance ladder little by little at your own pace, and stop when you are satisfied.

Please note that there is such a thing as an "amateur-swl", that never gets a license. THAT IS OK! While many amateurs will prod you to get one, one can be just as dedicated to the hobby and wrapped up in it from an swl standpoint. You may gravitate to becoming licensed on your own, but that's not the totality of it all - amateurs should be just as helpful and courteous to SWL's as they are to fellow hams. If not, they are being hypocritical.

Whatever you eventually choose, you can count on support from me.

 

[scan_madison]

Thanks to all so far; it has been encouraging.
Here's one article that I have recently read:
$4 SPECIAL

The feedline is twinlead and it talks about using a 4:1 balun to connect coaxial.

 

[WA8ZTZ]

Thanks to all so far; it has been encouraging.
Here's one article that I have recently read:
$4 SPECIAL

The feedline is twinlead and it talks about using a 4:1 balun to connect coaxial.

Just get some RG6 at the hardware store or electrical supply or where ever. Nowadays it is easier to find than the 300 ohm twinlead.
Also, RG6 is cheap, you can find it for less than .10 per foot. Don't worry about it being 75 ohm... for receiving it won't make a difference, no need for any matching device. The point is there is no need to buy expensive exotic coax for what you have in mind. RG6 loss at HF is negligible.

 

[nanZor]

I'd heed ZTZ's advice with the coax. Keep it simple at first - establish a baseline of what a very simple dipole sounds like.

What I'd hate to see is you picking up some twinlead (yeah, still around), but at the same place you got it, see a 4:1 / 300-75 ohm tv-type balun (yup still out there), not knowing about THAT type of balun only being good for 50 mhz and up. It would severely attenuate your 20m dipole.

The 75 ohm coax, and two wires are good enough to get started to get a feel for things on that band. You might be able to get an adapter and a box to make it easier to solder / attach the wires to so you don't have to hack up the ends of the coax - which can be aluminized wiring and a pain to work with if you aren't skilled with it. Or, yes, you can get some 50 ohm cb type coax and go from there.

Once you do that, you can start to specialize / upgrade should you need to. It's part of the fun, and more educational about *why* you *may* need certain things. It's how to gain real-world experience, and relate to what may be said in forums - 'cuz you've been there yourself!

 

[jwt873]

My first three years on HF was done with a Heathkit HW-100 connected to a 20 meter dipole. (With no balun). I made all sorts of contacts all over the world.. (but the sunspot numbers were a lot better back then)..

For receive only a dipole will work great. But, for transmitting, you'll need to either make it longer or shorter by a few inches in order to obtain a good SWR. The calculated length of a 20m dipole is about 33 feet.. Since it's easier to cut wire than lengthen it, put up a 35 foot dipole. Then you'll only have to cut to get it resonant when you're ready to transmit.

 

[ka3jjz]

I'm surprised no one here has mentioned the good old off center fed dipole, (older texts called this a windom). If the OP has the space, that's an antenna that will perform just fine for receiving, and will do OK for transmit too (altho in some cases you might need a transmatch for some bands, dependent on the installation and the actual length).

That 20m dipole will work OK during the day hours, but at night it's going to be too short to be efficient on the lower bands Mike

 

[Lauri-CoyoteFrostbite]

I too think that the feedline should be coax.... RG6/58/59/8/11 etal.--- it really doesn't matter for a receiving antenna, and it won't make much difference if you later use it for transmitting- you are going to have to adjust the thing then anyway unless you were really lucky to hit resonance right off.
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But that's not why I am adding a Two-Cents---
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Irregardless of what design you decide, I suggest you take the time to make this antenna as "workman like" as possible-- that is, mechanically sturdy and professional. If you decide to use coax to a centre insulator, support that coax properly- don't Mickey-Mouse it; like hanging it off the bottom of that insulator. Make perfect solder joints and weatherproof that whole assembly well. Use quality ceramic insulators and (preferably) a copper clad'd wire for the dipole.
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I say all this because poor solder joints, water in your coax, leaky cheap insulators-- all might seem to be working ok, but they'll degrade the antenna overall- and you won't know it other than the thing "stinks"....it was a good plan, but a poor execution.
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Where and how you place the antenna will also be very important- keeping it as clear of potential noise makers- power lines and such is all quite intuitive- but also your home's electronics- WiFi system, etc's -- may not be so evident. And don't forget those static (ligthning) issues.
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Good Luck !
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Lauri
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[Fast1eddie]

All excellent posts, lots of good advice here. Me, I have always enjoyed making my own antennas and have enjoyed the "lessons learned" from them. Licensed as Technician, I didn't think there was any voice activity on 20, just cw, sstv and data. Apartment bound until I meet Ms. Right which I don't think is gonna happen anytime soon. Just no point in upgrading for now, but I apologize for deviating.

The OFCD is a great antenna if one has the real estate for it.

Best of luck to you and let us know how you make out.