T9A10

ANTENNAS AND FEED LINES · Antennas: vertical and horizontal polarization, concept of antenna gain, definition and types of beam antennas, antenna loading, common portable and mobile antennas, relationships between resonant length and frequency, dipole pattern

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In which direction does a half-wave dipole antenna radiate the strongest signal?

AEqually in all directions
BOff the ends of the antenna
CIn the direction of the feed line
DBroadside to the antenna

Why A half-wave dipole has a doughnut-shaped pattern: current flows along the wire, and radiation is strongest at right angles to that wire, which is called broadside. Plotted in the plane of the antenna this looks like a figure-8, with two lobes perpendicular to the wire and deep nulls off each tip. That is why you aim a dipole by turning it sideways to the station you want to work.

Watch out Radiating off the ends is exactly backwards, since those are the null directions; an equal pattern in all directions describes an isotropic radiator, which is only a theoretical reference, and the feed line direction has nothing to do with the pattern.

Dipole = figure-8: strong off the sides, deaf off the ends.

HamSandwich explanation, first draft. The question and answers are the NCVEC text.

T9A10

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