New Antennas - Fast Tuning

 Hello there!  I've been making a bunch of contacts recently, thanks to a couple of new antennas at my house.  Things have been rather busy, so I didn't get to detail all the construction steps, but there was something "new to me" that I tried with both of these antennas, and I wanted to share - I did the "one-cut tuning" method for both of these, and it worked out great!

     If you're curious about the one-cut method, you can jump to the last section.  If you're curious about the antennas I did it with, here's the quick info:

Fan Dipole

This one had a saga...I gave the "real-time" account on twitter as I worked on it over several weeks, but here's the short version: Due to being busy, it took me a while to get it up.  Once it was up and tuned, but before I even made a single QSO on it, a storm brought down the tree holding one end up, so I had to start over.  Good news - it's now in the air!

CoopTenna

     This was another "from junk" antenna, that I built, basically because the antenna deities told me that if I built a giant ground plane (chicken coop) I had to put an antenna on top of it to keep them happy.  It's made from an old fiberglass extension pole (spray painted black) with a wire running up the middle, and a short whip on top that I can slide in and out to make it tuneable.  

One Cut Tuning

     I had read about "one cut tuning" in an article on ham universe a while back, but it basically goes like this:

Cut your antenna to length using the standard formula of 468 / frequency (in MHz)

1. Make note of the exact length of each half of the dipole.  It's easiest to work in inches or centimeters.  We'll call this (L1)
2. Put the antenna up into its final position.  Note the frequency where the actual SWR "dip" is.  We'll call this (f1)
3. Make note of the "desired" frequency - i.e. where you want the dip to be. We'll call this (f2)
4. New Length = (f1)/(f2) x (L1).
5. Trim (or fold back) so that the antenna halves are your new length.
6. Put the antenna back up, and go get on the air - you're done!

The things I was curious about, that I couldn't find anywhere, and my newly discovered answers were:

1. Does this work for a fan dipole, or does the interaction between elements screw things up?
   1. For me, Yes, it works!  The "new" frequency ended up being a little bit off from my target, but it was close enough that I was still under 3:1 everywhere I wanted to be on 80m, and under 2:1 across all of 40m and 20m.
2. Does this work for a vertical, when you're basically only working with half an antenna against a ground plane? 
   1. For me, Yes!  I did the exact same method for the length of the vertical, so I only had to put it up once, bring it down to tune it, and then put it up for good.

Done and done!