Whether you parallel dipoles or not, the textbook formulas are only a
starting point; and if you put the dipole lower than 1/2 wave high, it is
not likely to have low SWR at the calculated point. Below the 1/2 wave
height, local earth under the antenna is coupled closely and affects
results. When multiple wires are in parallel, it increase this capacity to
earth.
The other factor that especially affect the results are the diameter of the
antenna conductors. Shorter lengths are needed for thicker wires, or
tubing. Likewise, paralleling dipoles for harmonic bands like 80 and 40,
will affect the length the dipole is cut to be resonant. Certainly at 80m
you will still need a tuner to negotiate the band with wire dipoles. You
may need the tuner on other bands.
Using the tuner eliminates some of the tedium of trying to get the right
lengths of parallel antennas.
To avoid cutting wire, make the antennas longer than formula and fold up the
wire ends as needed to tune to the part of each band you want.
As others noted, spreading out the legs rather than close parallel legs will
be easier to get tuned with SWR meter or Antenna Analyzer.
-Stuart
K5KVH
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