Citation
Abstract
Precise determinations of the transmission medium loss and noise temperature contribution are important to the performance characterization of low noise microwave recelving systems and thermal noise standards. Tropospheric loss is frequently inferred from microwave radiometer noise temperature measurements. Interpretation of these measurements requires an inversion of the radiative transfer integral equation. This is inconvenient even with computer techniques. Although there have been many published studies of the radiative transfer equation, this article provides a very accurate solution in terms of a rapidly convergent power series. This solution is applicable to a low-loss medium with either uniform or nonuniform loss distributions. A four-layer atmosphere model is investigated to demonstrate the accuracy of the solution relative to the model. These solutions for total loss range in accuracy from about 0.001 dB (~0.06 K) at 0.1 dB loss to about 0.01 dB (~0.6 K) at 1 dB total loss. Applications include thermal noise standards and single- and dual-frequency water vapor radiometers.
Details
- Volume
- 42-69
- Published
- June 15, 1982
- Pages
- 179–188
- File Size
- 549.5 KB