Current distribution and input impedance of a loop antenna in a cold magnetoplasma

A study is made of the current distribution and the input impedance of a circular thin strip-loop antenna immersed in a cold collisionless uniform magnetoplasma. Assuming the loop axis to be aligned with an external static magnetic field, exact integral equations are formulated for the current distribution on the antenna, when it is subject to the excitation of a slice voltage generator. It is shown that, for a narrow enough strip, the equations can be approximated and solved analytically. Closed-form expressions for the antenna current distribution and the input impedance are derived and analyzed, with special emphasis placed on the resonant plasma case. The results obtained are compared with those following from existing approximate theories, and are applied to the analysis of the antenna characteristics for the whistler frequency band in a magnetoplasma modeled upon the earth's ionosphere.