Performance of a 20 cm short active AM/FM monopole antenna for automotive application

The performance of a very short active monopole AM/FM-antenna with a length of only 0.2 m (7.9
ⁿ
) is investigated and presented for automotive application. An advanced high impedance amplifier concept enables the realization of such a very short antenna on base of a lean monopole design which is easy to manufacture. The parameters and the conditions which determine the performance of the design are investigated and explained. Measurements in the field show that the new antenna has satisfactory performance in comparison with common passive rod antennas of 0.9 m (35.4
ⁿ
) length, both for the AM and FM range, if the density of strong FM broadcast stations is high, the co- and neighbour channel interference being predominant in comparison to the noise and reduction of sensitivity.