Prototype Development of FM Directional Antenna for Automotive Application 1999-01-0256

A new type of directional antenna, to be installed in a vehicle, is proposed to achieve an acceptable gain, fading reduction and the suppression of signal distortion for the FM broadcasting reception. This antenna consists of several antenna elements, a phase-synthesis circuit and a switching system. The circuit synthesizes the four patterns which are oriented toward the front, rear, left and right directions of the vehicle, respectively. The system switches the patterns from one direction to another, depending on the received voltage at a time. A prototype directional antenna, with four elements installed on the front and rear glasses of a vehicle, was fabricated and field-tested. This antenna had the smaller fading than the Pole one by 7 dB and the same fading with the diversity. In the weak field the lowest level, the 1% point of the distribution of the received voltage, was better in the directional one than in the Pole one by 3 dB.