Wednesday, January 30, 2013

Antenna Modeling and Making

I've literally been working on this post for a while, just haven't had the time research what needed to be researched. Still not done researching either ;-) This is what I would call a first effort.
After reading the latest antenna-centric issue of QST(way back in March 2012), I was a little disappointed. I knew I would be when I saw the front page and read "Special Ad Section Inside!"
hmmm,
I was hoping to read more about actual antennas. That is not to say that what articles there are not excellent, they are well worth reading. I guess I just can't get enough reading in on antennas. I'm always looking for a good idea or three. After looking through the magazine, I decided to work on modelling a multiband antenna project from the book I received when I rejoined the ARRL.
The idea is simple, you use shorted quarter wave stubs off the end of the antenna to isolate resonant sections. That's easy enough to understand, right? Ok, so I needed to see this antenna, and think about it for a second, and then I got it.
PROS:
Multibands without tuners!
   This is a big win for me, anytime I get to avoid a tuner is a good time.
Relatively simple to build!
    450 ohm Feedline, antenna wire, solder, insulators, and measuring tape. No traps to wind, no coils to dip, no ultragreezy uber kul big dollar capacitors either. Just wire, lead, tin, plastic.
CONS:
Mostly full size on lowest operating band.
    OK by me, I've got room for a 40m Dipole in the back yard.
Needs three supports.
   Could be a big deal to get all straightened out.

The model:
https://gist.github.com/1935227
Click on the link, and copy and paste the NEC file into a text file, save the text file as a .nec.
I'm pretty sure I'm doing it the wrong way :)
The internets so far have been no help, they simply don't know how to model this.
The build:
I will build this antenna in stages, testing each stage as I complete it, the object being a permantly install, no tuner triband antenna on 10, 20, and 40m.

Tonight begins the build. First Up, 10m Section.
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