J-pole: Where a choke is no joke
Measurements reveal the effects of common mode current on the J antenna.
Search Results for: j-pole
Slim Jim vs. Traditional J-pole Antenna
Real measurements of a Slim Jim antenna and traditional j-pole antenna reveal the truth about their respective gain and pattern.
Mast Mountable J-Pole Antenna
The J-Pole antenna’s long and storied design history is due for one more chapter to mitigate the longstanding mast current and reliability issues.
Have your J-Pole and ground it too
Tame the predictable mast currents found in any j-pole antenna grounding conductive mast using a simple stub. Shown is empirical evidence why this is a problem and a very simple solution all future grounded j-pole antennas should incorporate.
J-Pole Antenna – Should I ground it?
To function as intended, the J-Pole antenna needs RF electrical isolation from its mount. Here’s why and in technicolor no less.
5/8 Wave J-Pole vs. 1/2 Wave J-Pole EZNEC Shootout
We examine if 5/8 Wave J-Poles are better than 1/2 Wave J-Poles.
Collinear 5/8 wave J-Pole vs. Collinear 1/2 wave J-Pole EZNEC Shootout
Another 5/8 J-Pole Design arranged as a Collinear… can it justify the complexity and extra materials?
Can a 2m J-Pole be used at 440?
Analysis to suggest you really can use a 2 meter J-Pole in the 70cm band.
1/4 Wave Monopole vs. 1/2 Wave J-Pole EZNEC Shootout
Myths abound concerning how J-Poles do so well. Here is an EZNEC shootout between a 2 meter J-Pole and a Monopole with radials.
Copper J-Pole Antenna on Play Set
Can a 2 meter J-Pole antenna work well on a child’s playset? Read and find out.
Antenna radiator decoupling stub flub?
Measurements and analysis suggest why quarter-wave stubs fail to completely isolate radiator conductors on multi-band antennas including the popular rollup 2m/440 J-Pole products. Possible improvements are shown.
Where quarter-wave radiator decoupling stubs work… and don’t work
Tests suggest transmission line decoupling stubs are not immune to the conductor past the stub.
HT Antenna Comparisons
Does one really need to upgrade the antenna that came with your HT? Presented are EIRP measurements of various aftermarket HT aerials to help understand the trade space.
J antenna and variations thereof
There are many ways to morph the basic J antenna into useful forms.
J Antenna Design Patent Grant
USD798847S1 showcases one more incremental step towards a J antenna that works with masts and feedlines.
Mast Mountable Antenna Patent Application
The “mast mountable antenna” patent application is now available to review and critique.
Antenna pattern plots: Good intentions vs. good data
In the 21st century should we believe antenna graphical gain data based on hope and hearsay? J-pole antenna gain drawings are a common bad example.
SlimJIM and Antenna Gainflation
Understanding why SlimJIM antenna aficionados hype the gain in their marketing and discussions.
The Coaxial Dipole
G4CQM provides details on a Yagi-Uda coaxial dipole driver approach for designers lusting after a 50 ohm self-balancing feed.
Repeaters, Antennas & Trigonometry
You need an antenna with energy at high take off angles to hit the hill top repeaters… right? Well, not likely. Let’s review the details and do the math to understand what’s needed for VHF terrestrial radio communication.
Of Horses and Hams
One example of how amateur radio provides safety and service to the pubic providing otherwise impossible communications using the “Magic Band.”
First SOTA Activation – Using VHF FM
My first journey to the mountains as SOTA activator was a success using minimalist VHF FM gear.