Question

Microwaves operate at a frequency of 2.40 GHz. Find the minimum thickness for a plastic tray with a refractive

index of 1.45 that will cause enhanced reflection of microwaves incident normal to the tray.

Answer 1

y (lambda) = c / f incident wavelength

y = 3 * E8 / 2.4 * E9 = .125 m incident wavelength

y' = .125 / 1.45 = .0862 m wavelength inside of tray

T = y' / 4 thickness required for phase change at bottom

T = .0862 m / 4 = .0261 m = 2.61 cm