I had a topic on the mind as I made my way back to the trailhead after a SOTA activation recently.
I get a lot of questions from readers and subscribers about resonant vs. non-resonant antennas and whether or not an ATU is a good or bad thing.
If you know me, you’ll know that I tend to lean towards qualitative research; meaning, I like to base my opinions on first-hand observations rather than laboratory or textbook explanations. Part of the reason is I’m not an engineer, so specifications and performance stats don’t influence me–I don’t understand them half the time–rather, I base my opinions on trying or field testing.
The proof is in the pudding, right?
So with the topic of antennas and ATUs on the brain, I decided to turn on the action camera and do an unscripted video on the trail as I hiked back to my car.
This video is essentially stream of consciousness: I won’t blame you if you skip it.
With that said, if you manage to stay awake for the whole video (congratulations in advance) I’m curious what your thoughts are so please consider leaving a kind comment!
Thank you & 73,
Thomas (K4SWL)
My favourite antenna is the PackTenna linked dipole I made up for the two money bands 40m and 20m
No tuner required
John
VE3IPS
That is an excellent choice!
Great advice all around!
Thank you Robert. Being the antenna guru you are, I’ll take that compliment! 🙂
I really try to use a resonant antenna all the time. I have the X5105 so I do keep a 85′ EFHW in my bag that I made just in case.
I have to say, I did enjoy the video and would encourage you to continue to do these. If you have a long trail to walk, why not? Maybe you could start a series, Trail Time with Thomas.
I will be checking my mail for my award.
Thanks for all of you efforts!
Ha ha!
Thank you, Brandon. The great thing about the X5105 is if you need to venture off resonant frequencies with the EFHW, you can! Thank you, OM!
Great discussion! For those who may be doing a long term (full day or weekend) activation, consider having more than one antenna. Maybe a resonate antenna for the most active bands, but also a non-resonate one with tuner for those bands that might be good for a short time. Also consider switching between antennas frequently on the same band. You might be surprised to find that a different one sometimes works better. An old contester once said…you cannot have too many antennas!
Yes, an excellent suggestion. If I take the family on another park camping trip this year, I’ll be installing more than one antenna at the camp site. Always nice to have options!
Watched to the end, not boring at all and certainly worth the time especially for newbies to QRP.
Many failures of QRP ops are the result of a fixed book learned attitude rather than a hands on and sometimes hard learned lesson.
The ability to resolve problems that crop up in the field is indeed priceless.
Keep the Vids coming!
John, KK4ITX
Thank you, John!
Thanks Thomas I really enjoyed the video chat. I am a new subscriber and have been really enjoying reading and watching the channel.
On the subject of ATU’s and stations in general.
I would like to focus on a perspective that you touched on at the end of the video. At the risk of stating the obvious I feel that it is very important to really understand the scope of the operation that you are planning to embark upon.
As an example, for a number of years I have been going for hour long QRP expeditions down to my local park during my coffee break mid morning. My goal is to make at least 2 CW QSO’s during this time. This makes me happy. Often I plan to go to a spot that I know well. For this operation, which is a short walk from my car, I take a shoebox with my trusty single band Norcal40A at 2 watts, my 3Ahr Battery, my 66ft EFHW and my HB coupler and trail paddles plus a piece of paper and pencil in addition to a small table that I set up under a tree. I launch the EFHW into a tree up 25ft using my launcher made of 3 fishing weights. I then make an inverted L with the EFHW trailing over a branch above my operating position. Very seldom do I fail to achieve my objective! It takes me about 8 minutes to be QRV with this station. I am fascinated by the idea of really defining the operation objective and tailoring the station and antenna to meet that need. In fact there is definitely room for improvement in this operation I have just described. I could probably achieve the objective with 300mW and a much smaller battery hi..
Now if I was trying to catch enough fish to feed 5000 hungry folks then clearly this operation would not cut the mustard hi!
I say. “Focus on the planned mission objectives” when deciding what to take. 72
Thank you, Dick. I really should have emphasized this even more. At the end of the day, it’s best to pack for the “targeted” activity. My set up for a SOTA activation of a rare summit will be completely different than what I would take to ARRL Field Day.
I love the idea of your coffee break expeditions! That’s a great, relaxing way to enjoy a little QRP in the field! Thank you for the comment!
Best & 72,
Thomas
Thomas,
Well worth watching until the end!
Your frequency agile function of the ATU should become the preferred argument for carrying an ATU. Eschewing perverse extremes on resonance is a winning strategy.
I’m thinking of promoting a new game. Based on the famous Waldo series, it’s Where in the World Is Thomas?
I have one summative comment on your video:
https://youtu.be/LzGBQerkvWs
73,
Frank
K4FMH
Ha ha! That’s a brilliant “summative comment”–! Thank you, Frank!
Cheers,
Thomas
K4SWL
Hi Thomas
Thank you for this common sense.
I always carry a tuner in my kit.
I also carry a choke as sometimes my coax feeder wants to be part of the antenna and radiate in an unwanted way. I have to choice of the TX end and the feed point end of the coax as options.
Keep up the good work.
73 Chris
A choke is a brilliant accessory to take along. I’ve been meaning to build one soon for my Minion SDR which is incredible sensitive to RF coming back to the rig. Thanks for your comment, Chris!
Thank you for this! … well, you can try a combination, take your EFHW (40m band) and make a link like at your linked dipole, but at the right place to operate that EFHW now in the 30m band. Greetings from Hamburg/Germany, Dietmar, DL4HAO 🙂
Great idea, Dietmar! Thank you, OM!
Thomas,
I enjoyed the walk and only wish I could have been there with you. A beautiful day and you made it even better with your talk.
Dave K8WPE
Thank you, Dave!
Sort of like when I mow, I sort out so much in my head when I hike. 🙂
Cheers,
Thomas
Now that my ISP, Telus, handles e-mail via Google, Google won’t let me respond any more via YouTube claiming that my administrator (who does not exist) won’t permit it, so I’m trying to post here!
Non-resonant antennas can be very good, though some are not. Unbalanced ones, if low impedance, can suffer greatly if ground losses are high. One way to avoid this is to use high impedance antennas (e.g. EFHW antennas). Another way is to use low-loss balanced lines for feeders — open wire is best, ladder line second best, double coax a very distant third. With well balanced antennas, ground loss becomes less important.
One non-resonant antenna which can be excellent is the extended double zepp, approximately 1.25 wavelengths long fed at its center (or an end-fed 0.625 wavelength antenna, but that is unbalanced and with relatively low impedance so ground loss becomes a problem). This is the longest length that can be used without developing significant additional lobes. It has a good bit of gain, though there will of course be nulls in its pattern — radiation that goes here, can’t go there. An 88 ft wire is such such an antenna on 20 m; it’s fine on 40 m and will still work on 80 m though you’d better use a low-loss feedline there and a good tuner since the SWR on the feedline will be pretty high. And of course it will work on the higher frequency bands though the higher you go, the more lobey it will get.
Tuners vary too. Some can be a lot lower loss than others. The Elecraft tuners are pretty good since they’re L networks; T networks are generally speaking lossier.
Great comments, David, thank you! You know, I’ve never thought about building a Double Zepp for field work. Noted! 🙂
Thomas,
As an avid fall and Winter hiker/camper. I love the format.
Makes me want to get out early this year!!!!
Please keep it up!
Tom,
Very good thoughts. One thing you said which resonated with me (pun intended) is that some non resonant multi band antennas are designed to be compact and easy to deploy. One such antenna is the NorCal Doublet which has 22 foot long legs of a dipole which has a parallel feedline fed to the balance line connections on a ZM2. It has dips adjacent to the ham bands and is easy to tune on 80m, 60m, 40m and 20m. I gave a presentation on it today. You presented some very good logic.
That’s a video you can run once to listen to the talk, then again with muted audio and some music to watch the hike! 🙂
Back to the topic – nothing controversial about your stance on the issue, we all can agree on “pick what’s best for the task at hand, the conditions, practicality requirements”. However, if we talk efficiency I think the potential losses of a non-resonant antenna are less of an issue than picking an antenna type that matches the ground conductivity in order to avoid ground losses and “cloud warming”.
I guess SOTA vs. POTA are extremes in this regard, you could be at a coastline park or a park with a lake and anything vertical you put up there will work great, while SOTA is prone to give you the lowest ground conductivity and worst ground losses on e.g. rocky ground.
I’m slowly trying to wrap my head around what types of antennas work best in such an environment, say, what’s giving you the lowest possible elevation angles without having to drape the ground with nn counterpoise wires and schlepping 1/2 mile of wire up to the summit. David (VE7EZM) mentioned EFHW and zepp-style antennas above, both very likely a good compromise between portability, stuff you already own and the special requirements of the location, but I’m thinking more along the lines of inverted-U style, maybe terminated antennas? Resonant or not, I reckon (or hope) giving more thought on focusing the radiation to where you need it will outweigh the worst tuner losses by several orders of magnitude.
Sincere thanks for all your work. You have peaked my interest in QRP SOTA as a former ham returning to the hobby in my retirement. Your work is informative, logical, on target and easy to understand.
Many thanks,
Rick NS3P
Thank you so kindly, Rick. The pleasure is all mine!
Best & 73,
Thomas
K4SWL