The exact kernel for cylindrical antenna

In the numerical calculation for a cylindrical antenna, the thin-wire kernel is widely used as a convenient approximation to the exact kernel of the electric-field equation. However, this thin-wire approximation is valid only if the radius of wire is much less than its length and the wavelength; furthermore, arbitrarily using this approximation may not obtain the convergent outcomes. The expression of the exact kernel for the cylindrical antenna, which would be useful in the numerical work, is presented.<
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