More typical industrial lenses would have deviations no larger than a quarter wavelength (λ/4).
The bottom half of the ring is three quarter wavelengths in length.
This is only correct for omnidirectional aerials with a length of a quarter wavelength or shorter.
A 900 MHz antenna may be three inches long for a quarter wavelength.
In the case of the fundamental first mode, it is a quarter wavelength.
The effect is most striking when a continental shelf is about a quarter wavelength wide.
By measuring amplitude to a quarter wavelength, it is possible to improve the resolution down to about 8 mm.
The J-pole is somewhat sensitive to surrounding metal objects, and should have at least a quarter wavelength of free space around it.
From the nodal point to the top of a loop is a quarter wavelength.
In the case of a mirror at normal incidence, the layers have a thickness of a quarter wavelength.
