REFLECTION AND TRANSMISSION AT A SLOTTED DIELECTRIC INTERFACE

Abstract

A theoretical analysis of a slotted dielectric interface is given for the case of a plane wave incident at an angle θi and polarized with the electric vector parallel to the slots. A variational solution yielding upper and lower bounds to the parameters of the equivalent circuit for the interface is given. A numerical example for a wave incident at an angle of 30° on a slotted dielectric with a relative dielectric constant of 2.56 at a wavelength of 3.14 cm. shows that the phase shifts introduced into the reflected and transmitted waves are of the order of 1°. Also the impedance transformation across the interface is just that due to the change in wave impedance. Such a slotted dielectric may be) used to match a microwave lens to free space. A theoretical calculation shows that the reflection coefficient does not exceed 5% for angles of incidence up to 30° in the wavelength range 3–3.28 cm. for a slotted section used to match a dielectric of relative dielectric constant 2.56 to free space. Without a matching section the reflection coefficient is 23% or more.