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Packable 20m or 40m antenna


#1

I have spent all my free time researching which radio to buy and have not looked into antennas at all. I am trying to finalize my equipment budget for getting started.

What would be a decent antenna for first time HF? I am looking for something for SOTA obviously, but also for use in a really small backyard. My backyard is an L shape, I estimate about 18’ for one length and 25’ the other length and about 8-10 feet wide.


#2

Either a dipole or an end fed. This is what 99.9% of all SOTA activators use.

I most often use a linked dipole for 20 / 30 meters. Cost a couple dollars to make and works great. You can add a section for 40 but I find it hard to get that much wire in the air on most summits. Nice tool for building linked dipoles here:

https://www.sotamaps.org/extras

If you construct the dipole well, it requires no tuner on the band(s) it is constructed for.

The other antenna I use frequently is an end fed with 9:1 UnUn. This antenna requires a tuner but is easier to put up on forested summits and doesn’t require messing with links to change bands. Also costs very little to construct, but is a little more complicated than a dipole.

Search on the reflector and you will find thousands of threads on this very subject =)

I suggest you build lots of different antennas and try them all to see which one you like. Here is another similar thread with a lot of good info:

Good luck!

-Josh


#3

Within your home backyard constraints it would seem the EFHW would be the most appropriate. LNR have a couple of choices or you could roll your own. of course you’ll need a high-point to secure it to also… such as the house, tree or pole.

I use a link dipole for SOTA and have a basic 20 & 40m design which I add extensions for 30m and 60m… yes I put up a 60m dipole in the woods… it’s not too bad to do most of the time…

GL, N2GBR…


#4

An end fed half wave (EFHW for short) set for 40m would also resonate at 20m (and other bands above 40m) without the need for a tuner and its potential losses. An EFHW also would not need the ground radial to work well. In your situation, I believe it would be your best bet. Also, you only need one support for it near the middle with both end at or near ground level. Simple!


#5

If I understood it correctly, EEHF is suitable mainly for the QRP operation. If you want antenna for 100 w transceiver, I will suggest linked dipoles. If I am wrong, somebody will correct me.


#6

Question for the OP.
What radio, does it have a tuner or no?

Malen
VE6VID


#7

I think the association of the EFHW with QRP comes from many QRP operators using them. They are easy to deploy is a major reason and as a for instance, I have one with coil at end of 20 meter section that with only 6 feet of wire at the end of coil give me 20/40 operation with 40’ of antenna. Linked dipoles work very well also; both can be made resonant and to handle desired power level. I have a dipole at my home QTH and use an EFHW when portable for ease of set up - both work.


#8

I do not have a radio yet, planning on getting everything next month. Whatever it is, will most likely be 5 watts, 15 if I save a little more for the elusive kx3.


#9

The EFHW will handle as many watts as it is designed to take At my home QTH, I have several antennas including an EFHW. They all handle full legal limit. In fact, one EFHW is designed to take even more than legal limit.

For SOTA, I use an EFHW with lowest usable frequency being 40m. It handles 100 watts from an Icom 706 with ease.


#10

Hi Casey,

I’ll go out on a limb and advise you to build a simple half wave dipole for your chosen band, fed by coax, supported at the centre feed point by a telescopic pole. If you include links in it to allow multiple band operation that will make it more versatile. But to start with you can build a single band antenna just to get the hang of it.

The dipole is the basis of all antenna theory and all antenna gains are referenced to the half wave dipole. Every ham should own and/or build one early in their experience of ham radio. When you use something else you can compare them with your dipole. And the secret is that not many will be as good and few will be better.

If you add links to the design (perhaps when building a second antenna) you’ll effectively be building something very similar to the Sotabeams band hopper.

You can safely ignore the purists and not use a balun (edit: for portable applications). Don’t worry about what anyone says. Slight differences might be made by using a balun on a coax fed dipole but the dx worked by mine says it is not vital for success. My dipoles (without baluns) have allowed me to work the world using 5w from an FT817.

As for fitting the same antenna into your backyard, that is another matter. Noise pickup in suburban lots is notoriously high at present and will probably increase. The main solution to that is unfortunately to operate from somewhere else, such as SOTA summits. Unless your home is in a uniquely noise free environment, you may experience a lot of interference on almost any ham band, but especially the HF bands. In my experience the end fed antennas pick up much more local noise than a centre fed antenna, but I may have been unlucky. your mileage and your S meter noise readings may vary.

Look at some blogs of successful activators for antenna ideas. You don’t need to restrict yourself to commercially built antennas, they are much more expensive than a home made one and don’t work any better.

I suggest looking at vk1nam.wordpress.com to start with, my friend Andrew (whose current callsign is similar to mine) has published many of his antenna designs there.

If you decide to build your own linked dipole, a handy calculator for wire lengths for each band is included in the sotamaps website linked above under “Mapping”.

73 Andrew VK1DA/VK2UH


#11

Thanks for the suggestions. I think I will start out making the single band dipole antenna. Get some hands on experience to figure out how ever thing works. I prefer making over buying for sure.


#12

I made 73 activations and the the EF trail friendly antenna by LNR has served me well. I have built them all including a center fed link dipole for 60-40-30-20 and an end fed link dipole for 40-30-20 and used all three for SOTA activations and I keep going back to the 40-20-10 that I use with my KX2. For 30 and 60, I simply use the ATU in my KX2. To prove to myself that I am not losing on performance against the “gold standard” - a center fed dipole for 20m I did a head to head test using WSPR - same QTH, same time, same power, same configuration I would use when deploying as in a SOTA activation (inverted vee), such that the antenna is the only thing that is different The results are here:

For sheer convenience - no contest - the LNR EF beats it (center fed link dipole) for ease of set-up and take-down. Believe me, in the middle of winter, where every second counts, or your hands will freeze or in the middle of a briar patch, or in very tight summits with dense tree cover, the edge of the easy to deploy antenna is for me, the most important aspect. The fact that I don’t really lose out on performance, at least on the bands it was designed for seals the deal for me. With a center fed dipole, you are dealing with three wires, the two legs of the dipole, and the feedline. These always choose to get tangled up in the most in-opportune times (while hurrying to pack up because of an impending thunderstorm, while hurrying to pack up because it is late and there are only 30 minutes of daylight left and 45 minutes to reach the trailhead, and your hands are frozen because it is 28 degrees and the wind is blowing at 25 mph making it it feel like 10F), while raising an antenna in the middle of a rainstorm. These lessons have always made me thankful I have something that is the easier to take down and after many activations, 60 at least, the motions are nothing more than muscle memory. (BTW - I use SOTABeams wire winders for both antenna and feedline). The end fed has the least weight pulling down on the mast - just one wire.

So EFHW dipole for me with just a feedline - no separate counterpoise.

If you do decide to make one instead of buying one - make an end fed link dipole for 40-30-20 - “the bread and butter bands” for SOTA. I made mine to weigh only 146 grams from Wireman 22 gage slinky wire and the links use Anderson Powerpoles.


#13

Excellent advice! I have been making HF dipoles for more than 60 years and I have never found that a balun makes any noticeable difference.

73,
Walt (G3NYY)


#14

When I put a current balun at the feedpoint of my home dipole, the noise floor on 20 m dropped 6 dB. A full S-unit of noise is noticeable.

That was the 1:1 QRP balun from Balun Designs. They have an interesting view of “QRP”, because that is rated for 250 W.

Of course, background noise should not be a problem on most summits, so a choke balun to reject common mode noise isn’t needed there.

wunder


#15

If you are going to get a radio with a built in ATU, then you should consider a Windom antenna. Windoms also one of the most common and practical types of antenna. With a little ingenuity, they can even be connected at the end, just like an EFHW, which means there is no (potentially lossy) coax to carry. As you will see in this post, they are also ideal as a first time antenna project:

The lightest version I have made so far weighs 184 grams (including the spool) which, whilst not the lightest SOTA antenna in the world, is pretty good for a Windom. The more reasonable feedpoint impedance of 200 - 300 Ohms also means potentially lower losses than random wires with 9:1 baluns and some other >1:50 impedance transformers; although other factors will also affect losses. Whatever you decide, I’m glad to hear you’re building your own. It’s much more fun than buying ready made antennas.
73 de OE6FEG
Matt


#16

Hi Ariel,

(At my age) I appreciate the benefits of quick deployment for winter activations. I sometimes find my iambic finger and thumb are cold before I even start making contacts. I have the LNR EFT-40/20/10 (12.5m long), LNR EFT-MTR-40/30/20 (19.8m long) and a SOTAbeams 40-30-10 linked dipole with 60m extension added. I use the linked dipole with a 9m pole and - when activating with my smaller backpack – one of the EFHWs with a 4m pole, so my experience isn’t strictly an A vs B comparison.

I operate the LNR EFHWs as slopers (unless there’s a convenient tree) with the matchbox end at full height of the pole and a RG174 feeder down to my KX2. Was your test of the EFHW done this way? Or. do you have the matchbox end at ground level directly into the KX2? Have you tried it both ways? And if so, does it make a difference?

73, Andy


#17

Andy,

My matchbox is always about 4 feet - 7 feet high while the wire is an inverted V configuration. I typically use the SOTABeams Mini Tactical with the Apex ~ 20 feet AGL and try to be consistent that way. I don’t see anything wrong with your set up though. Slopers have a little bit of directionality compared to the omni-directional inverted Vee. The EZNEC models seem to say that higher off the ground is better. I have not tried to test with the matchbox at ground level.

Ariel NY4G