On this page 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.
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
Antenna Height
G5RV and Variants
The x-Pole - The Lack of Data is In...
VHF/UHF Dual-Band Antennas
Detailed Antenna Primer from K5QHD
A Casual Discussion of Antenna Gain Myths
Antennas 101 - Basics - de Ward Silver NĜAX
5/8-wave Antenna Design per CAI Networks
Simple 5/8-wave Antenna - de W9WQ
Antenna Info - Basics - de Walt Fari W5ALT
Simple Antenna Drawings via Buxcomm
(J-Pole addicts note the direct feed versions with choke! Still begs for radials!)
1:1 Balun Demonstration - YouTube de IZ2UUF
Note only baluns but current chokes are of benefit here.
End-fed v Dipole: Effects of Common-mode Currents - YouTube de IZ2UUF
"Zepps", j-poles, anything without a proper counterpoise can cause this serious problem.
NO1PC: Antenna and Counterpoise Basics
After you watch the YouTube demos above, you'll want to see RF circuits visualized.
NO1PC: Foolproof $50 Dual-Band Base Antenna
A simple base-mount kit and either of two proven dual-band mobile antennas
is one of THE most reliable ways to get a legit dual-band antenna with adequate gain.
A Tram 1465 or 1470 base kit ($25) and your choice of 'whip' are no-brainer get
up quick for home or portable use.
Antenna Height Article from Mike Banz, AA3RL, on QSL.net
How High Should It Be / How Far is LOS - Horizon Calculator
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."
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.
Page 2 - G5RV - Author: Louis, G5RV Himself
We all really need to understand what this antenna is, more importantly what it is NOT!
Many have analyzed and provided modeling (because NO antenna test field data exists) and the variations of coverage and stray RF experiences... just build a 1/4-wave ground-plane!!! Smaller, cheaper, same gain, known radiation pattern, no stray RF issues.
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.
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 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 and the return RF goes... where? This logic escapes everyone.
One 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.
W8JI End-Fed Details
One of two pages explaining counterpoise else common-mode RF issues.
AA5TB End-Fed Details = Needs Counterpoise
More evidence that a counterpoise is needed else common-mode RF on feedline.
AA1ZB J-Pole Data with very telling modeling
More evidence that a counterpoise is needed else common-mode RF on feedline.
A More-Correct J-Pole
A correct way to do the off-center-fed-dipole thing people claim/think a stub-tuned j-pole is.
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??
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. It is comparable to the original Larsen NMO-2/70.
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.