Electromagnetic Fields Radiated by a Circular Loop with Arbitrary   Current
  We present a rigorous approach to compute the electromagnetic fields radiated by a thin circular loop with arbitrary current. We employ a polar transmission representation along with a Kontorovich-Lebedev transform to derive integral representations of the field in the interior and exterior regions of a sphere circumscribing the loop. The convergence of the obtained expressions is discussed and comparisons with full-wave simulation and other methods are shown. 
Mohamed A. Salem and Christophe Caloz
physics.class-ph