Letters to the Editor

The question: "How does a dipole receive?" The core of this question appears to lie in a comparison of the physical area of a dipole and its capture area. For example, assume a dipole antenna one meter long and 10 mm in diameter, oriented toward the E vector of the incoming wave. The physical cross section normal to the incoming wave is 0.01 m². The resonant frequency will be close to 2 m, 150 MHz. From the relation, the effective aperture is 0.13 times the wavelength squared, about 0.52 m². Thus, the antenna is capturing energy from an area some 50 times as great as the physical area of the antenna.