Site attenuation with log-periodic antennas

Site attenuation measurements made with biconical antennas below 200 MHz are found to agree rather well with calculations based on point dipole antennas. The log-periodic dipole antennas used above 200 MHz differ more drastically than the biconical from an ideal point dipole. Discrepancies arising from the use of log-periodic antennas are examined, and a simple modification of the site attenuation model is offered to improve agreement. A simple model is proposed for the log-periodic dipole antenna. It accounts for the dependence of the position of the active element on frequency. Normalized site attenuation calculations for fixed antenna heights are dramatically improved because of the sensitivity of the location of attenuation peaks to the phases of the signals