Capacitance Hat Pedestrian Mobile Antenna

This idea stemmed from the coming HFPack gathering at Hamvention this year. Their calling frequency is 18.157.5usb. I have never really done any /PM operating before so I figured I would give it a shot. The radio I am probably going to use is my IC-718. I know, it isn't a very compact radio, but it is fairly light and will get me on the air.

Another note before I describe the idea is all of this occurred in the course of about 6 hours - from the initial idea stimulation to the construction and getting on the air (tuned up, no contacts though).

My first idea for the antenna was a whip/mast that is 6' tall with a cap hat on top. The mast was to consist of a PVC pipe supporting a wire. The cap hat would be made out of tape measure pieces secured to a PVC cross connector.

Once I started getting materials together I realized I had some aluminum pipe that I could use for the mast instead. It is the center section and one outer section of the separation boom for two Cushcraft 13B2 antennas. I bought 1 antenna and this boom used from a guy. The pipes
have come in handy for all kinds of things! Anyway, the pipe works very well for this project because the two sections telescope. That means I can adjust the height of the antenna to tune it.

So, now my idea has taken a new form - from the original PVC pipe mast with the cap hat to a telescoping aluminum pipe with a cap hat. The cap hat is still made out of tape measures, 30" of 1" wide tape for each spoke.

One big question I should address with this antenna is how it actually mounts to the pack. Well, my back pack has a pocket right against my back that is supposed to be for a water bladder. So it has a zipper right on the top of the pack. It is on the pack side of the back plate/frame. So, I made an H-frame out of PVC. It uses a T connector on the bottom with two equal pieces of pipe
pushing out







Edit: 8/24/07

Its been a long time since I posted anything new here. I figured I would update this first.

The antenna works. I ended up using my TS-2000 at Hamvention /PM. Yep, it was heavy. The rig and my lawnmower battery for power were just under 50lbs. With my pack and all loaded for Hamvention I was toting around 60lbs. Not fun.

The H-frame was poking my tailbone the whole time, so I got a nice rash there. However, that was due to the battery pushing against the H-frame. This setup probably wont be too bad with a lighter rig/battery (such as the FT-857D and a 12 or 18AH AGM/SLA battery.