Terahertz Molecular Absorption Peaks
Atmospheric Water Vapor and Oxygen Resonance Lines in Sub-THz Bands
Sharp physical absorption spikes where atmospheric water molecules absorb radio energy, dictating which frequency windows are usable.
Technical Explanation
Unlike lower radio frequencies where the atmosphere is largely transparent, sub-terahertz and terahertz signals collide with the rotational resonance frequencies of polar molecules—chiefly water vapor (H2O) and oxygen (O2). Severe absorption peaks occur at 118 GHz (O2), 183 GHz (H2O), and 325 GHz (H2O), causing attenuation exceeding 100 dB/km. 6G network designers exploit these physical realities: using transparent 'transmission windows' for communications and high-absorption peaks for ultra-secure, eavesdropping-proof short-range communications.
Key Functions
- Defines international frequency windows for long-range vs short-range 6G links
- Identifies high-absorption peaks for secure, self-attenuating whisper links
- Requires dynamic rain-fade and humidity compensation algorithms in base stations
- Enables atmospheric humidity and gas concentration sensing directly via radio path loss