Comments on "Input Impedance of Coaxial Line to Circular Waveguide Feed" [Letters]

The author read with interest the above paper in conjunction with the correction to it. While attempting to apply Harrington's well-known development for a coax/rectangular waveguide transition to the coax/circular waveguide transition case, the authors arrived at results and conclusions which are highly erroneous and misleading. As explained below, (4b) and the expression for X/sub 1/ in (6), the reactance part of the input impedance, are both incorrect. Even if the expression for X/sub 1/ in (6) is corrected, the reactance series is clearly divergent.