Estimating of RCS of AFAS Based on Ionospheric Heating

In the experimental researches of ionospheric heating, an interesting phenomenon was found: irregularities were excited in the heating experiment, which could scatter radio waves in a special way. The scattering is highly sensitive to the direction of geomagnetic field, and it is termed as AFAS (Artificial Field Aligned Scattering). A number of experimental researches were carried out by using the Platteville high power heating facility and other communication equipments. From these researches, people found that the RCS (Radar Cross Section) of AFAS is quite great, which may be as large as 80dB•m2. This is very useful for scattering communication. To study the application of the AFAS in communication, the estimation of RCS is important. A mathematical model was developed, which is based on the theoretical and experimental researches of the ionospheric heating, the characteristics of the scattering on F region and the scattering theory of irregularities. Comparison of the results between model and theory show that the model is applicable. Using the model, the RCS of AFAS in the frequency range of 20 MHz and 100 MHz were calculated, and a RCS of 80dB•m2 was obtained at low-level of VHF. Our calculation supports that the maximum of RCS occurs when the radar beams are in the direction perpendicular to the magnetic field.