Coupled Antennas and Transmission Lines

The problem of coupled antennas is reviewed; unbalanced currents in and radiation from transmission lines are discussed briefly and resolved into transmission line and antenna problems. The use of sections of transmission line as coupling links between antennas is discussed qualitatively and illustrated in terms of a colinear array. The principles of phase reversing and of detuning stubs and sleeves are explained in terms of coupled circuits in which a section of transmission line may carry transmission-line currents, antenna currents, or both. Methods of driving transmission lines and of feeding antennas using transmission lines are discussed from the point of view of minimizing unbalanced currents on the line.