Roll Your Own
This roll up antenna is a version of the antenna that I also build with a PVC housing. I built them either for 2 meters, or as a dual band 2/70 version.
The antenna in this photo was built as a 2 meter single band antenna, and cut for the APRS frequency of 144.390 mhz, as I built it to use with my APRS-In-A-Box portable station.
The measurements that I have provided you with for building the antenna, has the SWR centered in the 2 meter band.
These antennas perform very well, and I have built dozens of them over the years. In fact I am using two of them on my home, and two of them at my work, one used for voice, and one for my APRS station in each location.
The 2 meter roll-up antenna featured here is a very simple build, and you can build one in 30 minutes or less, depending how nicely you finish the antenna. All that you require for tools are a soldering iron, a tape measure, and a razor knife.
To build yourself one like the one featured here cut for 2 meters, start by aquiring 54 inches of 300 ohm TV twinlead, a panel mount BNC, and 12 inches of RG 174 coax..
Begin the construction by measuring 37 1/4 inches down from the top of the twinlead, and with a razor knife, cut a 1/4 inch notch on one side ONLY of the twinlead, sectioning out 1/4 inch of the copper wire. Only remove enough material from the twinlead to remove the wire, as not to compromise the integrity of the twinlead.
At the bottom of the twinlead, strip the two copper wires back, and then solder them together.
Then measure up from the bottom of the twinlead 1 1/4 inches, and expose the wires on both sides.
Then take 12 inches of RG 174 coax, strip a 1/2 inch of the shield away, exposing the braid and center conductor.
Solder the BRAID of the coax to the copper wire on the SAME side of the twinlead that the notch is cut in. Then solder the center conductor of the coax to the other wire located on the opposite side of the twinlead. Shrink a length of shrink-tube over the solder connections to finish the job.
Strip a 1/2 inch of the end of the RG174 coax, and then solder a panel mount BNC in place on the coax.
Before soldering the BNC in place, you may want to slide a small length of shrink-tube over the coax, allowing you to dress up the solder connection of the BNC once you are done soldering the BNC in place.
You will also want to place a short section of shrink-tube over the notch cut in the twinlead, although it is not required, but it gives the finished antenna a nicer appearence.
You also will want to punch a small hole in the top of the antenna, allowing for a piece of dacron to be formed into a loop to hang the antenna from a tree, or where ever you might want to hang the antenna when it is in use.
If you measure carefully in building this antenna, you will find that you do not need to make any further adjustments to the antenna, as the antenna will have a low SWR across the 2 meter band.
Click on photo for a closer look....