Portable 'J' Pole Antenna For 2 Meters
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This antenna is simple, cheap, and great for travelling, since it
may be rolled up and stored in a suitcase.  It might take from
30-60 minutes to construct, depending upon your level of experience.

I just finished mine, and the SWR measured 1.5:1 or better over the
whole 2m band.  Your mileage may vary.

Materials:
6 feet of 300-ohm TV antenna twinlead.
suitable 50-ohm coaxial feedline, with choice of termination at one
end (PL-259, BNC, etc.)
Electricians tape and/or RTV sealant



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   A   B                 C                                       D
(Not to scale.)

The dimensions are very critical in this design (according to the
designer.)  Measure twice, cut once!

_Before you cut the twinlead_, remove about 1/2" of insulation from
each conductor and the dielectric insulation between them at one
end of the twinlead.  Twist them together so that they lie flush
against the end of the cable, and solder them together.

Measure exactly 54-1/4 inches from the wires you just joined, and
cut the cable (segment A-D in diagram).  The cut end of the cable
will remain unattached to anything, and is the top of the antenna.

Measure exactly 1-1/4 inch from the joined wires at the bottom
(segment A-B in diagram).   Using a single-edged razor, or a sharp
hobby knife, cut small v-shaped cuts _on the inside_ of the insulation.
_Carefully_ scrape the insulation away from the wires, without
nicking through the conductors.

Measure exactly 15-1/4 inches up from the  v-shaped notches
(segment B-C in diagram).  Cut away a 3/8 inch section _of only
one_ of the couductors (point C in diagram).

The coax feedline _must be an odd-integer multiple of quarter
wavelengths.  Remember that these are electrical wavelengths,
not physical.  This depends on the velocity factor for the
particular coax that you choose.  For example, RG-58 coax has a
VF of 66%, which, at 146 MHz yields a quarter wavelength of
13.34804791 inches.  One convenient odd multiple is 27, which
gives an overall cable length of 30.033 feet.

Solder the coax to the connectors at the 1-1/4 inch mark in the
v-notches (point B in diagram).  It's wise to tin the conductors
before soldering.  Tape them and the exposed wire at the bottom.
If the antenna will be exposed to weather, it's wise to seal
the connections and open coax end with RTV sealant.

To hang your antenna, you can tape a non-conducting clip, such as
a plastic clothes hangar to the top.

Check your SWR, and as long as it's below 2:1, you are on the air!

73 DE N1QNK
Jim