Space Radiation Damage Measurements in the Earth Synchronous Orbit

For direct measurement of the integrated radiation dose experienced in Earth synchronous orbit, p-i-n diodes were flown as radiation dosimeters on LES-6. The diode, which has a lifetime of 10-4 seconds in the intrinsic region, was originally developed as a neutron dosimeter, but can detect 1-MeV electron fluences as low as 1013 e·cm-2. Observations over three years in orbit are presented.     

Pulse Compression Results Using Metallic Reflective Array Lines

Radar pulse-compression results are presented for the first reflective-array compressor (RAC) dispersive delay lines (DDL) with both metallic reflecting arrays and phase-compensating films. The time-bandwidth product of the devices reported is approximately 400. Operation in a recirculation loop with a 37.5-dB Taylor weighting filter yielded 36-dB near-in range sidelobes. RMS phase errors less than 0.71 degrees across the band were achieved. Greater than 50-dB rejection of spurious response is achieved in the far-out range gate region. The potential for high-quality cost-effective fabrication of metallic RAC DDL for system applications is explored.     

Half-Plane Scattering Applied to ILS Grading Criteria

A technique for calculating the derogation in the difference in depth of modulation (DDM) signal, used for aircraft glide slope guidance, due to slightly rough ground surfaces is developed. The contributions to the scattered signal from diffuse and specular scatter are treated separately. The diffuse derogation is calculated based on empirical data, and an average variation is presented. The specular contributions to the variation in the signal is calculated based on expanding the half-plane diffraction solution in terms of the ground roughness. A specular scattered deviation about the mean signal is then obtained by statistically averaging over normally distributed ground heights. Results of the analysis indicate that substantial relaxation in grading criteria can be effected.