This equation shows that, for a standing wave, the complex reflection coefficient and impedance repeats every half wavelength along the transmission line.

Each fringe - or band - represents a change of one half wavelength in the width of the gap between the glass and the workpiece.

The current on the Lecher line, like the voltage, forms a standing wave with nodes (points of minimum current) every half wavelength.

This type of antenna is a special case where each wire is exactly one quarter of the wavelength, for a total of a half wavelength.

Consider the case of a center-fed half-wave dipole antenna in free space, where the total length L is equal to one half wavelength (λ/2).

From this, a square, one half wavelength (on 790 kHz), 625 foot tower was constructed in 1938.

These waves will cancel periodically along the line causing nulls every half wavelength.

So it is a half wavelength out of phase with the first wave when they combine, and the two waves cancel.

The antenna is an electrical half wavelength, or multiple of half wavelengths.

The minimum impedance occurs when the thickness of the crystal is a multiple of a half wavelength of the acoustic wave.