Influence of temperature and frequency on microwave dielectric properties of the lunar regolith simulant

The dielectric constant of the surface material may be found from the reflection and transmission coefficients, and plays an important role in the lunar regolith study. In order to study the dielectric properties of the lunar regolith, the lunar regolith simulant is made according to the making procedure of the CAS-1 simulant. Then the dielectric constants of the lunar regolith simulant are measured with 85070E Aiglent microwave network analyzer over the range of 0.2-20 GHz and the temperature in 25.1, 17.7, 13.1, 11.5, 9.6, 8.0, 4.1, - 0.3, - 4.7, - 9.5, - 18.7, - 27.7, - 32.6℃, respectively. The Odelevsky model is employed to remove the influence from the water in the air on the final effective dielectric constant. The result indicates that frequency and temperature have clearly influences on the dielectric constants of the lunar regolith simulant. The real parts of the dielectric constant increase fast over the range of 0.2-3 GHz, but the real parts decrease slowly over the range of 4-20 GHz in total. The opposite phenomenon occurs to the imaginary part. The influences of the frequency and temperature on the brightness temperature are also estimated based on the radiative transfer equation. The result shows that the variation of frequency and temperature results in great changes to the microwave brightness temperature of the lunar regolith.