Ham Radio . Magnum Experimentum
Antennas, experiments, engineering and other articles of interest to radio folks.
Measurements and analysis suggest why quarter-wave stubs fail to completely isolate radiator conductors on multi-band antennas including the popular rollup 2m/440 J-Pole products. Possible improvements are shown.
The J-Pole antenna’s long and storied design history is due for one more chapter to mitigate the longstanding mast current and reliability issues.
The BigIR antenna from Fluid Motion looks like a winner, but there are some concerns about the 80 meter option.