Some time ago, I bought a small, lightweight telescopic fishing pole from a Chinese vendor on eBay. It’s about 19.5 feet tall and collapses down to about 26 inches. It’s a great size for backpacking or transporting on my bike. It weighs practically nothing. In fact, it’s too light for supporting anything but a lightweight vertical wire. Although I have used it a few times to support various antenna configurations, I never really found one that was a “keeper.”
Since I had some time over the long holiday weekend, I scratched out a quick design for yet another vertical antenna and cobbled it together with parts I had on hand in my junk box. I designed it to operate as a base-loaded resonant vertical on both 40 and 30 meters. On 20 meters and higher, it operates as a non-resonant wire; thus, an antenna tuner is required on those bands. Along with the loading coil, the matching unit contains a 1:1 choke balun to isolate the feedline. Both the choke balun and tapped loading coil are wound on toroids and mounted in a small, plastic enclosure. The radiator is a 19-foot piece of #28 wire. I could have shortened the radiator to make it resonant on 20 meters also, however, I went with the longer radiator for better performance on 40 meters. I used four 12.5-foot radials that I made from a 25-foot roll of cheap speaker wire.
Normally, I like to use the “build a little, test a little” approach. Since I don’t have the luxury of space at home for antenna testing, I just took my chances and built the whole thing. I headed out to a local park yesterday to give it the “smoke test” and see how close I came with my loading coil design.
It took less than 5 minutes to set it up. I used an antenna analyzer to take some initial measurements. On both 20 and 30 meters, the resonant frequencies were low and fell outside the band. I still have some work to do there. On 20 meters and up, the KX3’s tuner loaded it up easily.
Next, I wanted to put it on the air. I started on 40 meters and used the KX3’s tuner to tweak the SWR. I called CQ a few times and eventually got a call from K4ALE in Virginia. Bevin said I was 559 with QSB. Despite the poor band conditions, we had a nice chat.
After I signed with Bevin, I set the antenna for 30 meters and kicked in the KX3’s tuner. I called CQ and was quickly answered by NN4NC in North Carolina. Jim gave me a 569. At times, the band would fade to just about nothing. As I was chatting with Jim, some drizzle started blowing in under the pavilion where I was sitting. So I signed with Jim and quickly packed up.
I’ll be doing some adjustments to the antenna over the coming weeks. It looks, though, that this could be a useful portable antenna, once I get the loading coil straightened out.
Since this is a work in progress, I left out the details for now. After I get the antenna working as intended, I’ll provide a detailed description, schematic and parts list in a future post.
72, Craig WB3GCK