In our last post, we built the Portable 2m J-pole antenna. Construction was relatively simple. Tuning is straight forward; but, it will require some experimentation.
While constructing your antenna, do not solder your feed line to the radiator and stub until tuning. I wanted a picture of the antenna complete for the last post and soldered before tuning. To properly tune the antenna, the feed line had to be unsoldered and moved.
Move the feed line on the radiator and stub until you get as close to 1.0:1 SWR. If you are unable to get the SWR down, lengthen or shorten the stub. I cut my antennas long so wire does not have to added.
This antenna had to be shortened. 1/4″ (6mm) of wire was cut and then the feed point adjusted. This process was repeated until the SWR was acceptable. In total 1″(25mm) was removed from this antenna.
Over all, this was a nice build. The antenna rolls up nice and can be easily stored in a backpack. A change in future versions will be a better way to setup matching. With the current construction, it is difficult to keep water out of the coax at the feed point. This is not a major issue for most portable operaterations. Here in Florida it seems like it rains every day; so, waterproofing is always a good idea.
- Using a LM317 Adjustable Regulator
- Basic Weather Station Using a D1 Mini Pro
- Single Lever Paddle For the uBITX
- uBITX 3.2″ Touch Screen
- Installing a uBITX in a Case.