Antenna References and Measurements
On this page, below, are links to additional on-site and off-site references providing some theory, practical, and data results from a variety of HF, VHF, UHF homebrew and commercial, base and mobile antennas.
Do not let antennas be any more mysterious than they should be be...
Antennas may seem magical, but they are not magic. There are basic foundation antennas like the half-wave dipole and quarter-wave ground-plane that are about as simple as can be - start there!
There are multi-wire antennas and complex multi-element directional rotating antennas, and there are dozens of compromises of any of these.
Basic performance requires a quarter-wave radiator and counterpoise. Gain requires a larger radiator and accompanying matching/compensation. Shorter/small = less efficient = less effective - PERIOD.
Antennas follow the same basic electrical theories as AC and DC circuits, voltage applied, current flow is induced, current must flow back. Cheat that and you cheat good RF!
Improperly terminated, improperly radiated RF is a bitch. At low-power levels like QRP with very compromised antenna constructs the issues are minor. At high-power levels improperly treated RF will make your station and operations miserables - perhaps your family and neighbors too.
It is easier and better to get this right than it is to cheat, cheap, screw this up and fight to apply band-aids to a gas tank leaking toward a flame.
Search, read, study, consider...
Antenna Basics - Types, Gain, Myths...
Simple Antenna Drawings via Buxcomm
1:1 Balun Demonstration - YouTube de IZ2UUF
End-fed v Dipole: Effects of Common-mode Currents - YouTube de IZ2UUF
NO1PC: Antenna and Counterpoise Basics
NO1PC: Foolproof $50 Dual-Band Base Antenna
Antenna Height - Most Relevant to HF
SWRMy goodness how this topic is mis-understood and abused...must read!
ARRL Article about SWR (may require member login)
ARRL Article about SWR
ARRL Article about SWR (may require member login)
- don't get lost in the Smith charts, the text covers things pretty well!
Generic Antenna InfoThis is where you get help unravelling all the myths and hey-Bubba non-sense...
Antenna Myths? Or basic observations and findings.
- Myths is not the way I would have presented this, but some good generic info.
A LOT of info and basic observations to consider.
G5RV Reference Points
A very good antenna, if you know what it is, is NOT, how to put it up and use it...
The G5RV is a much mis-understood but highly popular multi-band HF antenna. The antenna MUST be hung high enough to allow the ladder-line/twin-lead section to be completely off the ground and free of surrounding objects as it is a radiating element and important factor in the antenna's function.
In my opinion, having hung and used two variants of it, this antenna is not for everyone given the height and length dimensions and requirements. Yes, it can work on many bands, with a good antenna tuner. As with all antennas and feedlines, especially in mixed/multiple antenna and band of operation environments, the feedline must be protected from becoming an incidental radiator of RF from outside to inside the shack. Well-grounded entrance panels and where prudent, current chokes at feedpoints are highly recommended.
A VERY VERY VERY important note about this construct used off-band: "However, on all the other HF bands the function of this section is to act as a "make-up" section to accommodate that part of the standing-wave (current and voltage components) which, on certain of the operating frequencies, cannot be completely accommodated on the "flat-top" (or inverted-V) radiation portion." - this not only suggests but admits there *IS* "hot RF" on the vertical ladder line. Beware!
The very basic drawings of this construct illustrate "standing wave" on the vertical line. This aligns with later EZ-NEC models and de-bunks "the ladder line does not radiate" opinions.
The G5RV Revisited - Exploring How/If This Construct Could Work Better...
J-Pole Reference Points
I don't tolerate junk science, unproven 'facts' and outright lies
Don't make me call this the junk-pole or slim-junk
Special Notice:After over a year of social media banter and subsequent inspired research I've compiled a LOT of test and reference information about the genre of J-antennas. The research is not my own, but the need to do the research from personal and related experiences is. I had tough questions and got some rough, unqualified answers to start, and in the absence of ANY better feedback, suggestions or hard data decided to dig much further.
"The results are in" - good, bad or indifferent - but compiled and freely available. The data is out there. The data appears to be valid, consistent, robust and comprehensive. Feel free to cross-check and provide equally legit data.
While the j-pole is a 'cute' or 'quaint' antenna it is one of if not THE most mis-understood antenna hams love to brag about. Even the proponents submit reference information with conflicting non-data and techniques - so it is impossible to tell which lie they are supporting. Have a look at a few quite similar descriptions and realities about this simple but not whole antenna construct in the links below.
Q: I submit and question - if this type of antenna is SO 'great' then why haven't Comet, Diamond or others provided their own cheaply reproduced version of them and made millions on the sensation? Why haven't the professional communications companies adopted them?
A: Most likely because:
The j-pole is quite simply an end-fed antenna with an impedance matching coupling point, or points. The nature of the feedpoint does NOT create a counterpoise or remove the need for one. The short-stub at the bottom you connect across does NOT leave a 1/4 wave or adequate counterpoise - it's just a matching stub. ALL antennas need a counterpoise or whatever you want to call "the other side" that supports proper and necessary antenna physics. PERIOD.
Aside from studying and rationalizing the physics and basics of ALL antennas, there is measured and anecdotal evidence that this antenna is not self-contained. The claims that it does not need a counterpoise are ignorant antenna modeling and testing facts. Not always realizing that the antenna NEEDS a counterpoise (as most antennas do - dipoles have them, ground planes have them...) and that in most circumstances the feedline is the counterpoise. That is often discovered to be problematic, but not for the reasons people assume. The solution most often applied (feedline choking) might fix the problem(s) encountered (common-mode, incidental radiator, etc.) but then deprive the antenna of its needed counterpoise.
Does choking the feedline improve the performance of the antenna? NO!!!!! It merely deprives it of a necessary half of the RF wave equation. Choking the feedline probably makes it WORSE - the RF field needs someplace to return to... where??? The answer is probably NO WHERE, so you end up with a very awkward unresolved impedance, SWR, radiation pattern mess.
As people experience the j-pole, especially in multi-radio (ARES deployment) environments they discover that there is a LOT of RF cross-talk between stations. Of course the first-guess is to choke the feedline. Since the feedline IS the counterpoise, choking it to fix common-mode stray RF problems immediately deprives the antenna of the only counterpoise it has. This logic escapes everyone.
J-Pole - The Obvious Solution
THE solution is simply to include/provide radials in the design and construction. This is described in at least one of the analysis references below. If you're already soldering a bunch of pipe together, how hard can it be to add a couple of radials - seriously? Make them out of #14 or #12 solid wire. Portable use? Fold them up to store/transport, fold them down to deploy. The added 30-seconds is certainly not life-critical to be technically correct and effective. PVC+twin-lead j-pole? No problem - a copper or brass washer with a 5/8-inch hole with radials soldered to it, a suitable nut to secure onto the SO-239 at the bottom... instant radial kit, instant PROPER end-fed antenna.
For all that - why bother? The j-pole is huge, provides NO appreciable gain, and presents stray-RF vs a simpler, smaller 1/4-wave ground plane. For real gain a base-loaded 5/8-wave (for VHF) is equally simple and much more effective.
The last point to consider if nothing else... there are NO, ZERO, ZIP, ZILCH, NADDA, UH-UH, NEVER GOING TO HAPPEN commercial/public safety/military variations of the j-pole/slim-jim. That is NOT because the likes of GE, Ericson, Motorola, Phelps-Dodge, Decibal Product, Tx/Rx, Telewave, et al are ignorant, stupid, clueless or missing out.
It is specifically because the concept, design, manufacture, implementation, deployment and use are so complex, unreliable, uneconomical and ultimately UNNECESSARY as to be non-viable, inferior, WORTHLESS.
There is NO way to reliably, consistently, commercially or technically make this contraption effective versus KNOWN GOOD RELIABLE CONSISTENT designs.
Hack away. Play. Experiment. Contemplate. Make unqualified claims of greatness. Snark. Troll, etc. There is NO WAY this antenna is viable other than a cheap ARES (whatever that is) gimmick. It's along the lines of the same junk design and construction of cheap Chinese portables without properly engineered chassis systems to provide adequate RF platform for rubber-ducky attenuators. This is indeed as much junk-science in proven RF fields as anything you can imagine. Enjoy your stray RF and pointless choking.
W8JI End-Fed Details
Second of two pages explaining counterpoise versus common-mode RF issues.
AA5TB End-Fed Details = Needs Counterpoise
AA1ZB J-Pole Data with very telling modeling
A More-Correct J-Pole
Dual-Band Mobile Antenna Reference PointsThis is where the great vs. sucks antenna review and performance stuff starts. There is no such thing as a great multi-band mobile antenna, nor mag-mount. Not physically possible.
Out of my own curiosity and further inspired by the many claims about this or that antenna being 'GREAT!' or 'better' or 'outperforms' some other "piece of junk" I've taken on some basic measurements of typical VHF and UHF ham antennas, starting with the oh-so-cute mini-mag mount dual-bander - and I'll just lay it out there - it IS junk for a ham antenna, but see the measurements in the pics. How is this even a ham antenna?? Mini-Magmount Mystery
The VHF Quarterwave on 440
Next up was the claim that a 1/4-wave VHF ground-plane makes a GREAT 3/4-wave on UHF, especially becuase VHF and UHF ham bands have a 3X relationship. Well, sort of, depending on where you want to operate - 144/432, OK. 145/445, not so much. As usual SWR does not tell the entire story... SWR does NOT provide ANY indication of impedance match which is the critical thing for your transmitter - a "gooder SWR" can still impose undo mis-match on the final PA, waste watts in coax, etc. Again, measurements and some dialog in the album.
Sampled here is a Tram 1180 - probably the best built and most consistent VHF/UHF dual-bander I've owned. I can't find my quarter-wave V/U dual-band pigtail so that album will have to wait.
These antennas follow-through the same measurement/resonance/operating range characteristics of the previous tests. The basic take-away is that no such antennas are ideal on both bands. The math and thus the construction do not have the same relationships as many multi-band antennas on HF (the 3.5, 7, 14, 21, 28 Mhz allocations) which are now confounded by allocations at 5, 10, 12, 18 and 24 MHz challenging 'easy' multi-band implementations.