= Dipole antenna
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A <dipole antenna> uses two conducting arms carrying an oscillating current, commonly fed across a central gap. Its changing charge and current distributions produce electromagnetic radiation. A short straight dipole has far-zone power proportional to $\sin^2\theta$ relative to its axis: it radiates most strongly sideways and has axial nulls. A practical half-wave dipole has a nonuniform current distribution and a different exact pattern and input impedance. Geometric wire length, electrical length and the surrounding dielectric or conducting structures all affect resonance and matching.
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