Hazardous and safe zone for 2600 MHz BTS

Hazardous and safe zones at 2600 MHz, D = 0.5 m

λ  = c/f = 3×10⁸ / 2.6×10⁹ = 0.1154 m
R1 = 0.62√(D³/λ) = 0.62√(0.125/0.1154)
   = 0.62 × 1.0408 = 0.645 m
R2 = 2D²/λ = 2×0.25/0.1154 = 4.33 m

 [ant]|--0.65 m--|-------4.33 m-------|----->
      | reactive |  radiating near    | far field
      | DANGER   |  CAUTION (beam)    | SAFE (public)

So the hazardous zone is within about 4.3 m of the antenna (mainly in front of it), and the public safe zone is beyond about 4.3 m, provided the far-field power density there is below the ICNIRP public limit of 10 W/m² (2–300 GHz). The exact compliance distance depends on EIRP; for example, an EIRP of 1 kW gives S = 1000/(4π × 4.33²) = 4.2 W/m² at 4.33 m, which is already below 10 W/m².

How non-ionising radiation is hazardous

(The "non-radiating radiation" in the question is read as non-ionising radiation.)

• RF photons cannot ionise atoms, but the fields make polar molecules (water) rotate and ions move; this energy turns into heat.
• The absorption is the SAR = σE²/ρ (W/kg). Above about 4 W/kg the core temperature rises by about 1 °C, giving heat stress.
• At 2.6 GHz penetration is a few centimetres, so the skin, eyes and testes are heated most. The eye lens has poor blood flow and can develop cataract; burns occur at high power density.
• Long-term, possible non-thermal effects (headache, sleep disturbance, IARC Group 2B "possibly carcinogenic") are still being studied.