Abstract :
Measurements are made on ground electrical field intensity in order to obtain a coefficient for the shadow, or diffraction factor. This factor permits the determination, with good accuracy, of the ground E field from the transmitting antenna to a point well beyond the radio horizon. The ground E field is of paramount importance in obtaining the nocturnal service area of an AM broadcast station. Nocturnal service area depends on the antifading properties of the transmitting monopole antenna. Critical study of the height-radius (H/a) relationship effect is made in order to determine the performance of the transmitting monopole antenna. The results are of interest, since they permit evaluation of the best H/a relationship for a determined antenna height, in order to obtain maximum directivity and maximum diurnal and nocturnal service area. Improvements in existing MF AM antennas can be achieved for high-fidelity stereo transmissions choosing the optimum H/a relationship. Measured data from reduced-scale models are shown and compared with theoretical predictions. Good agreement between them has been achieved
Keywords :
amplitude modulation; broadcast antennas; field strength measurement; radio broadcasting; AM broadcast station; MF AM transmitting monopole antenna; antenna height; antifading properties; diurnal service area; ground electrical field intensity; height radius effect; high-fidelity stereo transmissions; maximum directivity; nocturnal service area; radio horizon; reduced-scale models; transmitting antenna; Antenna radiation patterns; Antenna theory; Current distribution; Diffraction; Impedance; Interference; Moment methods; Radio broadcasting; Transmitting antennas; Wire;
