Short Takes #24: Antennas, Tuners and a Miniature CW Paddle

Yeah, a person at work has a Tesla, I've ridden in it a few times and I agree it's a pretty nice car, sort of on the expensive side, but none the less a very nice car. My issue with it is the range, +-350 miles won't quite cut it for me since I drive 45 miles each way to work and we don't have any chargers available here at work. Maybe when the Prius dies, I'll look into the Tesla again, but my last Prius went over 300,000 miles before I had to donate and buy a new car, so given the fact that I hope to retire in about a year, hopefully the Prius will out last me!

73

 

Well Dave you know me well enough by now, first I got to make a comment, question is as always are my comments going to be thoughtful, and worth while reading??

Here goes, Antennas, they are volumes of articals and books written on antennas. we have paper books, electronic books and books that have not been written yet, Ok a bit crazy but we all know everyone has a diffrent spin on antennas.
I have a couple rules on antennas. #1 rule is do not buy something you can make that is just as good or better than one Joe Blow in China has made.

#2 Why bother with building a antenna if you got to use a match box? It is just as easy to build a resonate antenna as one that is not.

I have three match boxes, oh some call them things tuners, which is a misnormer a matchbox does not tune anything. now a set of wire cutters and a antenna analyzer can tune an antenna.

#3 Why do I have one matchbox let alone three? Well it is fun just to see if I can hook up to that rusty 51 packard and make a QRP/CW contact, or Grandma's close line. Curiosity drive us some times to do odd things.

#4 Why multi band antennas? well some times a Multi band antenna comes naturaly, like when you cut a length of wire resonant for 40 meters It also will be resonant on 20 and 15 meters if I remember correctly ??, Harmonics. But then you got a Multi band antennas that are unnatural and are very loosy because most use traps.

#5 I have made several antennas over the years, does that make me an expert, certainly not I am far from it I have scratch built 6 band Hexbeam that uses what is called an Air Coaxial center post made up with several short lengths of coax with taps for each band, cut precisely for each band to be resonant in short Traps. I have made verticals that use loading coils, dipoles with loading coils.
We refer to these as compromised antennas, not my favorite, this type of antennas are like a multi tool , they will do severl things but not well.

#6 I prefer the simple wire antenna for single band use, or multi bands when I am blessed with harmonics. Hay when the frequency's Nome's give you a gift that works, why ignore it.

#7 And last I prefer using endfed antennas for portable use, I said (end fed), not Random Wire, which is actually not random.

After all these years Nothing will beat a length of wire for being efficient, easy to make an antenna with, Low in cost, and works just as well or better than the latest fancy Dan's out there.

That is my Two Rules, OK more than two with some opinion throwed in there.
Keep your wire cutters sharp and your analyzer charged.

 

Hi Ken, well worth reading, for sure. Thank you for doing this - much appreciated. Lots of value in what you have added to the thread, Dave

 

Hello Dave-
Thank you for the kind words! And you're very welcome, my pleasure. I just wanted to comment to the other operator that built the same antenna that I did. If interested, here are the links:

https://www.dj0ip.de/my-favorite-antennas/all-bands-vertical/

https://www.dj0ip.de/vertical-antennas/simple-multi-band-vertical/

I chose this for the advantages listed in the links, plus I desired omnidirectionality, low take-off angle for DX, no radials, multi-band operation, needs only one high support (less than 45 feet, I skipped the pole and just hung the wire- and used a rope at the feedpoint to counter the pull from the feedline to keep it all fairly vertical), and simplicity. I also constructed the balanced feedline (ladderline), making the whole antenna quite inexpensive. For as simple as it is, it's a decent antenna. As mentioned, the ZS6BKW is usually better (during testing of my setups) on most bands, but 15m was a major exception. In addition, I consider it a nice backup if/when ice, wind, etc. eventually takes the ZS6BKW down.
I also love making antennas, one of the strangest so far was a 20m slot (multiple U). Unfortunately a falling tree took it out and I've not repaired it yet.

Here are a few hundred designs to keep any experimenter busy!

https://www.qsl.net/va3iul/Antenna/Wire Antennas for Ham Radio/Wire_antennas_for_ham_radio.htm

73,
Rob
VA3RTG

 

How is the action on that mini-paddle? Looks a bit stiff... functional, but for field use, I'd still opt for a BY-1. However, like you said it could be a good back-up or emergency paddle.

Always a good read, Dave, TKS OM

Hank

 

I don't have the luxury of putting up resonant antennas, so tuners are a way of life in my stations. I've had my MFJ-971 and my SST T-1 tuners since before I was licensed.
I also gave up car ownership long ago, so if I'm going to the park to play radio, I don't want to carry tuners and jumpers and junk. I took 35 feet of wire, determined the resonant points by winding it to the right length for each band. I put knots at those points and now I can have a tuned antenna from 20 to 10 meters, just by winding the wire out to the right knot.

Now that's a real antenna tuner!

 

Why fewer resonant antennas and increasing user of antenna tuners? This is primarily influenced by a lack of available space for resonant, single band, and highly visible antennas; caused by several underlying trends. (1) The price of single family homes on larger lots continues to increase. (2) The aging demographics of licensed amateur operators means more are entering retirement, many have lower incomes, and as older individuals, frequently want or need to downsize their housing for health and economic reasons. (3) Small homes, condos, and apartments often have antenna regulations. All these factors contribute to a growing interest and need for unobtrusive and stealth antennas that can be used in limited spaces and cover multiple bands with sophisticated multi memory auto switching antenna tuners. These underlying trends also support a growing interest in mobile, portable, QRP, and remote station operation. It's another instance where social and economic trends are causing shifts in the use of technology. Jon - K3MAH

 

Mid to High End rigs come with auto tuners. In 1972, the engineer next to me in Rochester, NY, was putting the final touches on a continuously variable auto-tuner for a commercial rig (which if you had $$, we would sell to an amateur). Ergo, auto tuners have been available as a built in option in commercial rigs for over 55 years. I started getting them in my amateur gear 25 years ago.

Note that in the waaaay back, like 50s, 60s, 70s...and earlier, there were continuous controls for the transmitter output, like the two variable caps of a pi net or caps and link adjustment. If this was a 5 band rig using the same tapped coil and variable caps, then on the lower bands anyway, you could match very high load Z and if the VSWR angle made it low Z, throw in some extra coax and get to high Z. Thus we didn't need any external antenna tuners to get a match. However, the consequence was often very low attenuation of harmonics for which I got several 'OO' cards...not the kind of QSL I wanted even as a kid.

 

The idea that tuners weren't meant to turn a cattle fence into an antenna sums up the issue. I think some believe that there is a "right" way to ham radio and the other ways are sloppy or lazy. Others, like myself, think that ham radio is about having fun and learning. Using a cattle fence as an antenna seems similar to seeing how many states you can work QRP. What a rush when it works, right? A lot of fun seeing what your results are. I had a 65' end fed half wave that had great SWR on 40 and 20, no tuner, low SWR. That was a blast to use, just push to talk, tuner out of the picture. But I love my 400' loop fed with window line into a 4:1 and into a good tuner. 160m? Sure. 6m? Sure. Whatever the radio can transmit on, my loop will get the signal out. That is fun, too. Some radio guys like the knobs and switches, etc. I love using a manual tuner but I have a good automatic tuner, too. I think so long as you're squeezing a lot of fun out of the hobby, you're doing it right. Different strokes, you know. Just have fun.

 

Hello all. Antennas and feedlines are a big gnarly subject and bristling with misconceptions and incorrect assumptions. The hobby would be improved vastly if people would take the time to do some reading. Designing an antenna isn't exactly rocket science, but it takes a methodical and rational approach. There's a thriving industry making "tuners", baluns and the like, and what I call the "SWR boogeyman". The object of the exercise is to transfer maximum power via the feedline to the antenna, and have the antenna radiate as much as possible in the direction we want. The real concern is feedline loss, not SWR. Your radio/tuner could indicate a very low SWR, but the feedline loss could be horrendously high, and the antenna losses could be also be high. Also, an antenna does not have to be resonant to radiate well. Don't believe me? It states this in the ARRL Antenna Book, and in other reputable texts, such as "Reflections" by Walter Maxwell. As Rob states "resonance isn't the Holy Grail of antennas as long as balanced feedline is used to avoid the high losses experienced when using coax cable under high SWR conditions". This is exactly right. For a single frequency antenna, cutting the elements to resonance and using coax feedline, and matching this to the Tx output is correct. For a maximum efficiency multi-band (HF) antenna that gives a high performance/price ratio, a simple doublet fed with open wire feeder down to an efficient tuner is the way to go. It will work great even with SWR values of hundreds to one!

 

Many of us old timers started life with vacuum tube transmitters. Many of these (the later ones at least) had a pi-network tank circuit to resonate the final amp circuit. When coax became king, it became necessary to match the high impedance output circuit to the low impedance coax . Before coax, a single wire feedline was often alligator clipped to the tank coil (through a cap) and the tank tuned to resonance with the aid of a light bulb! Pretty much all power developed by the finals was absorbed by the load minus feedline losses, in this case almost none. The reflected power is not dissipated in the finals, but flipped in phase and goes back up the feedline. The fact that modern radio manufacturers include a built-in tuner is to me an admission of defeat, and they are capitalising on the general ignorance of their customers.

 

Can you match the unknown impedance of a cattle fence? Absolutely. Will it radiate useful energy? Maybe, maybe not. It might just warm up the fence wire and surroundings.

 

Another point - an antenna doesn't magically start to "sing" at resonance. It radiates equally well on any frequency (with some consideration for wavelength measurements). The only distinguishing feature of an antenna at resonance is that feedpoint impedance is purely resistive, and this R is not necessarily 50 ohms. So an antenna at resonance could still have a large feedpoint mis-match and therefore high reflected power and losses. For example, a half wave dipole at resonance will have a feedpoint impedance of about 73 ohms R. This will give a feedpoint SWR of about 1.5:1 and trimming or extending the antenna will only make matters worse. Moving the feedpoint along the antenna will change the impedance in accordance with the voltage and current curves on the antenna. In the case of a center fed half wave dipole, feeding it with 72 ohm cable would give a near perfect feedpoint match (only at its resonant frequency) hence lower feedline losses. The transmitter will not be bothered at all by the small mismatch so almost 100% of the power developed by the finals will be absorbed by the antenna.

 

Thanks Hank. The tiny paddle is perfect as something that literally weighs nothing and can be included in your go-kit in order to have a spare. I can get 15-20 WPM out of it but as you say, it's stiff. That's OK -- as a backup, it's great. Dave

 

Really well stated and great reply, Jon. You're right . . . I see those same trends all around me, Dave W7DGJ