The admittance of very long cylindrical antennae

The admittances of long cylindrical antennae ranging in electrical half-length from ßh = 0.3 to ßh = 63.1 have been determined experimentally when the antennae are centre-driven by a 2-wire line. The measured values are in good agreement with the King-Middleton1 second-order theoiy for the shorter antennae and with Wu´s theory2 for the longer ones. Particular care has been taken to avoid an unbalanced current on the feeding and measuring line, since such a current can lead to serious errors in the measured driving-point admittance. The measured admittance of the long antenna was extrapolated to infinite length and found to be in agreement with the theoretical values reported by Papas7 and by King and Schmitt.8