New effect in near-field thermal emission

Area of Science:

• Physics
• Electromagnetism
• Radiophysics

Background:

• Thermal radio emission from absorbing dielectric media is influenced by electromagnetic field distribution near the surface.
• Understanding the emission formation depth is crucial for remote sensing applications.

Purpose of the Study:

• To experimentally discover and theoretically describe a near-field effect in thermal radio emission.
• To investigate the dependence of emission formation depth on antenna characteristics and proximity to the surface.
• To establish a method for obtaining information about subsurface temperature distribution.

Main Methods:

• Experimental investigation of thermal radio emission from an absorbing dielectric medium.
• Development of a theoretical model to analyze the contributions of wave and quasistationary field components.
• Measurement of emission characteristics with varying receiver antenna size and height.

Main Results:

• A near-field effect was experimentally observed, altering the effective depth of emission formation.
• The effective formation depth was found to be less than the skin-layer depth and dependent on antenna parameters.
• A theoretical framework was established to differentiate between wave and quasistationary field contributions to Plank emission.

Conclusions:

• The discovered near-field effect provides a novel approach for probing subsurface temperature profiles.
• Antenna characteristics significantly influence the interpretation of thermal radio emission data.
• The developed theory enables a more accurate analysis of Plank emission near a radiating surface.