THE IMPEDANCE OF A CENTER-FED STRIP DIPOLE BY THE POYNTING VECTOR METHOD

The impedance of a center-fed strip dipole of width w and thickness t, with t << w, is obtained by the Poynting vector method, With w also t aken to be small with respect to the operating wavelength (w << lambda ) the surface current on the dipole is modeled by the classical sinuso idal standing wave along its length, There are, however, appropriate t ransverse singularities assumed at the edges of the strip, The Poyntin g vector method leads to a two-dimensional integral in the transverse coordinates involving the classical mutual impedance between filamenta ry dipoles located on the surface of the strip itself as well as the a bove mentioned transverse edge singularities, A Legendre series expans ion of this mutual impedance (the coefficients obtained by numerical i ntegration) leads to a rapidly convergent series solution (eight terms ) for the overall impedance of the strip dipole, Numerical results are provided for a variety of strip widths, thicknesses and lengths, They are compared with the impedances of equivalent circular dipoles of ra dius a = (w + t)/4 and good agreement occurs except for quite wide str ips (w = 0.05 lambda).