>"Besides it being easier to find a certified protector for 50 ohm coax, a
>resonant dipole or a fan dipole fed with coax will have a nicer pattern and
>perform better than the W7FG dipole with ladder line on non-resonant
>frequencies. John KK9A"
Performance of the W7FG dipole (aka Dipole-Doublet and CF Zepp) is relative, as
shown by Cebik in the PDF attachment. The radiation pattern will be more
complex and less predictable than on resonant bands but it will produce gain
and nulls in various directions over a resonant dipole -- sometimes to an
advantage, sometimes not.
Given the flexibility of running coax to an outside-mounted ATU, then 600-ohm
open feeders to the antenna, I find that the benefit of this configuration
outweighs its disadvantages when compared to multiple resonant dipoles. With a
136 ft. dipole-doublet, the pattern mostly replicates a resonant dipole on 80m
and 40m where I'd rather not have the many lobes and deep nulls that occur when
using the antenna on the upper bands.
In this configuration, a certified Z50 surge protector can still be placed on
the coax at the outside-mounted ATU, or at the outside point of premises entry,
depending on the local code requirement. If at the ATU, the protector's ground
stud will require connection to the AC mains bonding point, generally not to
exceed 20 ft. in length. The NEC goes into additional detail when it comes to
longer bonding lengths. For that reason, placement at the premises entry point
is probably easiest, especially if it's close to the AC mains bonding point.
Paul, W9AC
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