Abstract
The connection between Johnson noise and blackbody radiation is discussed, using a simple thermodynamic model. A microwave radiometer is described together with its theory of operation. The experimentally measured root mean square fluctuation of the output meter of a microwave radiometer (0.4°C) compares favorably with a theoretical value of 0.46°C. With an r-f band width of 16 mc/sec., the 0.4°C corresponds to a minimum detectable power of 10-16 watt. The method of calibrating using a variable temperature resistive load is described.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
Author information
Authors and Affiliations
Rights and permissions
Copyright information
© 1946 American Institute of Physics
About this chapter
Cite this chapter
Dicke, R.H. (1946). The Measurement of Thermal Radiation at Microwave Frequencies. In: Classics in Radio Astronomy. Studies in the History of Modern Science, vol 10. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-7752-5_11
Download citation
DOI: https://doi.org/10.1007/978-94-009-7752-5_11
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-009-7754-9
Online ISBN: 978-94-009-7752-5
eBook Packages: Springer Book Archive