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The input admittance and near‐field coupling of a TEM‐driven concentric annular slot array
Author(s) -
Irzinski E. P.
Publication year - 1977
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs012i002p00213
Subject(s) - admittance , coupling (piping) , physics , boundary value problem , ground plane , wavelength , concentric , mathematical analysis , optics , geometry , topology (electrical circuits) , mathematics , electrical impedance , quantum mechanics , telecommunications , antenna (radio) , materials science , computer science , metallurgy , combinatorics
A theoretical study of a pair of TEM‐driven concentric annular slot antennas radiating through a perfectly conducting ground plane is described. The problem solution is accomplished in the rigorous Maxwell equation‐boundary value sense. Closed‐form solutions are obtained for the annular slot admittance and mutual coupling. These expressions include the effects of higher‐order TM modes which exist only in the evanescent state. Approximate solutions are obtained to a number of infinite coupling‐type integrals which are subsequently employed for numerical evaluation of the admittance and mutual coupling for several annular slot configurations. The effects to the annular slot admittance and mutual coupling are separable into those that are purely TEM induced and those that result from the presence of the beyond‐cutoff higher‐order TM modes. The analysis shows that the higher‐order mode perturbations are relatively minor provided that the width of the annular slots is less than one half wavelength. The method of analysis presented can be readily extended to multiple annular slot ring arrays under any set of TEM‐driven conditions.