A new approch to the evaluation of HF aircraft antennas

An improved method is described for establishing a factor of merit for an airborne HF transmitting system, taking into account both the transmitter power and the antenna radiation patterns at different frequencies. A large number of communication events are postulated, having different path lengths, directions, geographic locations, and times of occurrence. Some of these events are successful while others are not, depending on the calculated SNR at the receiver sites. The factor of merit is defined as the ratio of the number or successful events to the total number of events postulated. A graph of the factor of merit of a particular system as a function of the transmitter power can be used as a guide in effecting a reasonable compromise between power economy and system performance. Graphs based on two or more antennas can be used to compare the antennas in terms of the relative powers required for a given system factor of merit or in terms of the relative factors of merit obtained with a given power.