Consideration on the measurement of current distribution on bent wire antennas

As part of the measurement of the current distribution on a bent wire antenna with a shielded loop, the electromotive force (EMF) induced on the loop is theoretically formulated, and the relation between the current distribution and the measured values is investigated. The EMF is expressed as a summation of terms involving the current and the derivative of the current with coefficients depending on the measurement point. The calculated EMF agrees well with the measured value. At points away from the antenna ends and bend, the EMF is proportional to the current, but near the ends and bend the difference between EMF and current increases. It is shown that the current distribution is easily estimated from the measured data. The authors also present the measurement of charge distribution using a small dipole. The expression for the open-circuit voltage of the dipole is formulated and compared with measured values.>