A Growing Concern
When it comes to understanding the performance of HF antenna systems, there are only a few tools. You can measure the impedance match with an antenna analyzer, you can model the antenna to see what you might expect the antenna to do, and you can listen and talk on the air to see how well [...]
My bamboo pull-up hex beam has been a work horse antenna for the last couple of years. It underwent a few changes from the initial design. I removed the 30 meter wires because the antenna was just too large to turn easily and get up and down between the branches with the space needed for [...]
After doing the ferrite transformer scaling experiments last time, and learning a bit more about what matters in these transformers, it was time to make a stab at designing one. Let me review the salient observations from the previous work. 1) More primary turns and primary inductance improve the transformer efficiency and low end performance. [...]
Top Band, as 160 meters is called, presents a a challenge because the long wavelength leads to large antennas. One can always play tricks with loading to be able to use a physically shorter length of wire. There are many articles on compact 160 m antennas, but this is not one of them. Rather, I'm [...]
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 [...]
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. [...]
True understanding of a problem is confirmed when one can validate theoretical model predictions with measurements. It is too easy to believe pretty pictures that modeling programs produce, especially when making meaningful measurements is so difficult. In this article I try to take the bull by the horns and see how close I can come to [...]
Squash Practice 