Monopole antenna decoupling with a radial-transmission-line choke

A method of decoupling a monopole antenna from surrounding conductive elements is demonstrated using a radial- transmission-line equivalent of a lambda/4 choke mounted at the base of, and concentrically with the monopole. The arrangement can provide a structure smaller in dimension and more convenient than a conventional lambda/4 choke at wavelengths greater than 1 m. The radial line performance is extremely tolerant of dissymmetry in the configuration of either the monopole or the inner termination. Measurements of radiation patterns of monopoles with electrically small radial-line chokes indicate variations as expected, which can be controlled through changes in monopole configuration.