SBIR-STTR Award

An important function of survivable c(3) systems is ground wave communication following a nuclear event. Antennas most likely to survive such events are buried or low profile near-the-earth antennas. However, the ground wave field strength for such antennas is not easily calculated. Usually, such calculations are based on comparing the antenna in question to a "standard" electrically short vertical monopole. Field strength curves are readily available for the "standard" antenna from such sources as the ccir recommendation 368-4. Such gain determinations at zero degrees elevation angle, however, assume perfectly conducting earth. This method cannot be applied to buried antennas since they would not radiate in a prefectly conducting earth. Their ability to radiate depends upon the earth's finite conductivity and permittivity. Therefore, other methods of calculation must be used. Tci proposes to utilize its analytical expertise to accurately analyze buried ornear-earth hf antennas and develop space wave gain, efficiency and ground wave strength of these buried or near-earth antennas. A goal of the effort will be to establish a relationship between the ground wavelaunching efficiency of buried and near-earth antennas and the more conventional vertical monopoles, which will permit the use of availableground wave propagation curves and calculation techniques to predict the performance of c(3) applications of buried and near-earth antennas.