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ANALYSIS OF APERTURE ANTENNAS IN INHOMOGENEOUS MEDIA.
CALIFORNIA INST OF TECH PASADENA ANTENNA LAB
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The object of this report is to calculate the admittance and the radiation pattern of aperture antennas fed by waveguides of arbitrary cross-section and radiating into dielectric slabs, whose constitutive parameters may be functions of position along the direction normal to the slab faces. For a given aperture field distribution the antenna aperture admittance and the radiation field are expressed here, for the first time, in terms of two auxiliary quantities directly related to the plane wave reflection and transmission coefficients of the dielectric slab. These quantities are the input admittance of the dielectric slab and the ratio of the total electric field amplitude transmitted at one end of the slab to the transverse field at the other, both calculated for plane waves as a function of incident propagation direction. This approach introduces a great simplification in the solution of the problem, particularly in the case of an antenna radiating into an inhomogeneous dielectric slab. A simple and powerful method has been devised for the computation of the input admittance of an inhomogeneous dielectric slab as well as for electric field ratio. In this case the impracticability of obtaining analytical results has necessitated the use of numerical techniques. Applications of theory are discussed. Author
APPROVED FOR PUBLIC RELEASE