A simple formula for the high frequency input impedance of the circular thin wire loop antenna

A formula is derived for the high frequency input impedance of a circular thin wire loop antenna. It allows for fast simulations, because it involves little numerical work, contrary to the previous models. A closed form is given for the first time, which can be written in a circuit simulator, for matching near the loop's second resonance. Simulation results compare well with published data, in the case of a thin wire.