Use of focused antenna for ionized trail measurements: Part I. Power transfer between two focused antennas

The transmission efficiency for power transmission between two identical circular apertures is considered. Each aperture is focused in a common focal plane which is located midway between them. The transmission efficiency is evaluated in terms of the percentage of the total energy flow through the focal plane which flows through a circular area of arbitrary radius, centered at the focal point and coincident with the focal plane. The results are used to estimate the diffraction error (leakage of energy around the phenomena to be observed) that arises when the focused beam system is used to probe a cylindrical ionized column in the focal plane. Kirchoff theory is used throughout, and perturbation of the focal field distribution due to the presence of the plasma is neglected. The effect of this perturbation has been analyzed theoretically and will be the subject of future papers.