Experimental vehicular angle-diversity antenna using mutual coupling

Abstract

A two-channel diversity antenna suitable for vehicle mounting has been demonstrated. It is effective for an antenna width of 1/8 wavelength, i.e., 4 cm at 900 MHz. This is narrow enough for two monopole elements to be encased in a blade fairing, and for the composite antenna to be mounted simply through one hole in the vehicle body, as a retrofit for a conventional single-element antenna. Although based on 5/8 wave element lengths, the same principle of operation would apply for, say 1/4 wave element lengths. The antenna is tolerant to a wide variation in the terminating impedance of the parasitic element, and to element spacing. Thus, the antenna is expected to have the practical advantages of being tolerant of fabrication error, and of the environment near the antenna. Simulated diversity performance is presented.