Dispersion Relations of Periodic and LOG-Periodic Dipole Arrays with Parasitic Elements

摘要

Dispersion relations were obtained for uniformly periodic arrays consisting of dipoles driven with glide-symmetric excitation from a uniform transmission line and interspersed with undriven, parasitic dipole elements. The effect obtained by introducing parasitic elements is to reduce the strength of the coupling between the uniform transmission line and the radiating modes of the dipole array at frequencies near the dipole resonances. This type of structure was investigated as a possible prototype for a log-periodic dipole array. The spatial dispersion curve for the L.P. array with parasitic elements was obtained theoretically by the method of coupled mode theory. It appears that the introduction of parasitic elements may enable the length of the active region of such an array to be increased, making possible an increase in directivity. (Author)