Transparent vehicle window antenna with capacitive connection apparatus

摘要

A vehicle window antenna (30) is a transparent, electrically conducting film disposed between the inner (21) and outer (20) glass sheets of a composite window glass. The antenna has a principal element (32) spaced from the upper edge portion (11) of the window aperture and an impedance matching element (38) extending downward from the principal element (32) to essentially cover the visible area of the window and form a slot transmission line with the remaining edge portion of the window aperture parasitically coupled to the principal element. The large area of the antenna provides a large capacitance producing high gain in a commercial AM band. An essentially transparent planar capacitive coupling member (50) made of an electrically conducting material is affixed on an outer surface (210) of the inner window glass (21). The capacitive coupling member (50) defines a planar area of at least 100 square centimeters plane parallel with an equivalent planar area of the principal element (32) of the antenna (30) to capacitively couple therewith through one glass sheet (21) and the interposed layer (22) of the window glass. The large capacitive coupling area reduces the impedance at commercial FM wavelengths to an insignificant level to prevent the capacitive coupling member from adversely affecting the impedance matching of the impedance matching element of the antenna. The AM gain lost by capacitive coupling of the antenna is at least partially compensated by high AM gain due to the large area of the antenna. An electrically conducting terminal member (52) extends vertically from the capacitive coupling member (50) near the upper edge of the window aperture on an area of the window glass hidden by vehicle trim (19). <IMAGE>