Microstrip antenna system having nonconductively coupled feedline.

摘要

A microcrisp antenna system having one or more conductively isolated resonantly dimensioned radiator structures disposed less than about one-tenth wavelength above a ground plane is nonconductively coupled to an intermediate layer of microcrip feedline structure. The microstrip feedline structure includes various microstrip transmission line segments fed with reference to the ground plane and including predetermined coupling locations positioned an odd integer number of one-fourth wavelength(s) from an effective r.f. short circuit to the underlying ground plane. Such coupling locations are also disposed proximate a predetermined corresponding feedpoint region of the radiating structure such that electromagnetic fields concentrated at the coupling location operate to nonconductively couple r.f. energy to/from the radiator structure from/to the feedline structure. The coupling location is preferably disposed at a widened and relatively lowered r.f. impedance coupling tab segment of the transmission line having a width dimension which is sufficient to provide matched impedance coupling to the corresponding feedpoint region but which is also substantially less than the dimension of the radiator structure transverse to its resonant dimension. The effective r.f. short circuit may be provided by an actual conductive connection to the underlying reference surface or by an r.f. open circuit termination located an additional one-fourth wavelength therefrom along the feedline structure.