Effect of nuclear radiation on microstrip and dielectric antennas in space

The effect of nuclear radiation in space on dielectric material used in microstrip and dielectric antennas is described. It has been shown that the primary effect of nuclear radiation on materials based on PTFE (polytetrafluoroethylene) is the reduction of molecular weight by breaking the large polymer molecule into smaller parts. There is an increase in brittleness, and this reaction is maximized in the presence of air. The degree to which PTFE is affected is essentially a function of the amount of energy absorbed regardless of the nature of the radiation. The susceptibility of electronic dielectric materials as a function of the total nuclear radiation dose is shown. Usually, the dose rate of 10 rad/h is quoted for the Van Allen belt. At this rate PTFE could operate for more than five years before a threshold level of damage would be detectable electrically and mechanically. Space-proven dielectric antennas are briefly discussed, with particular emphasis on the GTE GSTAR satellite reflector antenna which is fed by a dielectric loaded horn array. The elongation loss caused by radiation on a number of polyimide materials is shown.<>