The J-Pole antenna is an end-fed 1/2-wavelength antenna
that uses a 1/4-wavelength long transformer section to supply the feed
voltage.
It is an ideal end-mounted, single-mast antenna that is cheap and easy to build and
very easy to tune.
The antenna on this page is
made from 1/2" copper tubing and it is soldered together with 1 plumbing
tee and 1 elbow. Copper end caps are used on the tops to keep out water.
The coax can be soldered to the pipe or attached with
moveable conductive clamps (recomended).
This
antenna needs no impedance matching if you use 50 ohm coax since the
resistance/reactance is 50 ohms. Once you have it mounted and connected to
your radio slide the center and braid conductor clamps up or down and
note the SWR reading.
If the SWR cannot be lowered to the desired reading you
may have to cut or lengthen the long section.
Shortening the antenna will raise the resonate frequency.
Get Dimensions for Your JPOLE
Units:
Frequency:
MHz
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