The standing wave forms with this desired pattern at the design frequency, f0, and antennas are normally designed to be this size. However, feeding that element with 3f0 (whose wavelength is 1⁄3 that of f0) will also lead to a standing wave pattern. Thus, an antenna element is also resonant when its length is 3⁄4 of a wavelength. This is true for all odd multiples of 1⁄4 wavelength. This allows some flexibility of design in terms of antenna lengths and feed points. Antennas used in such a fashion are known to be harmonically operated. COUNT 4
QSN1 What frequency are antennas normally designed to be? ANS1 f0 QSN2 What can be added to f0 to create a standing wave pattern? ANS2 3f0 QSN3 What multiple is essential for wavelengths? ANS3 1⁄4 QSN4 How are waves which are used in the ways discussed controlled? ANS4 harmonically