A Growing Concern
When you first meet the J-Pole, you are forgiven if you don't quite grok how it is supposed to work. What is that 'J' for anyhow? When I have questions like this, I get out the 4NEC2 modeling program, and see what it says. Let's start out with the basic model -- the J consisting [...]
The bamboo Moxon I built for the 20 meter band earlier this summer convinced me of the power of compact two element antennas. When I was showing the Moxon to a friend, he pointed up to a nearby tree and said "There's the place to pull from," pointing to the crotch of a tall branching [...]
A couple of years ago I designed this antenna which had the good property of substantial low elevation gain and the model generated consistent and predictable 4NEC2 results. The wire that it would replace was already "pretty good" so it's taken two years to decide to build it. But I always had the feeling that [...]
As much as I love all of the wires up in my trees, I've come to realize that a little real gain and directivity would be nice. However, my trees are really in the way for a a typical tower and a beam antenna, so I am left to consider what resources I have and [...]
Antenna modelers are often left with a question about how to handle baluns and impedance matching devices when using the NEC codes. Often we just ignore all of the feed nonsense and place the source right on the antenna wire to find the pattern, drive impedance, etc. You can also just reflect the driving impedance [...]
I've been using a spool of RG-6 CATV cable of dubious quality for quite a while as my go-to source of antenna feed line because I happened to have the spool in my junk collection. Using the 75 Ω cable got me thinking about why we care what impedance the cable is and how matching [...]
Here are the slides for a presentation given to The Valley Radio Club on May 3, 2019. The hope is that the slides contain enough detail that the reader could easily build and run the examples in 4NEC2. Practical Antenna Modeling Power Point Presentation Practical Antenna Modeling PDF format slides Using the NEC Codes With Examples [...]
When I first started playing ham radio, I ran across the GR5V antenna. It seemed that a lot of folks had them, and there seemed to be a fair bit of controversy about how good/bad they were. For whatever reason, I bypassed the design and went to an off-center-fed dipole instead. Now with more experience [...]
Simple pieces of wire are not the most sexy ham radio antennas, but they are probably the most ubiquitous, if for no other reason than that their cost-performance ratio is very good. When it comes to the lower bands, there is little else that is more practical for most of us than using a wire [...]
After a few months of pondering how to build a simple pull-up vertical collinear antenna, I think I've finally got it! The motivation for such a design is the fact that I have tall trees for a support and can actually pull such an antenna up into the trees to 100 ft. or even higher. [...]
