Measurements of human body microwave radiation

Major problems of registering microwave radiation of human body have been considered. It is pointed out that they are caused by at least three factors which may considerably influence the experimental results and their interpretation, namely: (1) properties of the radiation (their low intensity primarily); (2) features of measurements that implement waveguide techniques; (3) peculiar features of the emission medium and the environment. For the purpose of dividing the overall radiation into equilibrium and nonequilibrium fractions it has been proposed: (i) to take into account the influence of the thermal emission background and the equilibrium radiation of human body on the results of measurements; (ii) to estimate correctly the energy of radiation arriving at the sensor element of the measuring device after leaving the waveguide; (iii) to take into account the radiation coming out of the inner layers of the body, as well as the dependence of the body radiation properties on the physical properties of the environment. In practice it would be necessary to measure the temperatures of the receiver and the radiating body, as well as the microwave 'body-measuring device antenna' system reflectivity subsequently introducing the relevant corrections into the registered data. For the purpose of measuring the reflectivity |/spl Gamma/|/sup 2/ of a body in the given environment, waveguide systems should be used providing a direct contact with the body and being completely consistent with the environment. The values of |/spl Gamma/|/sup 2/ measured under these conditions in the air across the 54/spl divide/78 GHz frequency range for different parts of the human body differ slightly but are mostly close to zero. It would be safe to conclude from the results obtained that the thermal emission capacity of a human body in the microwave range is close to that of blackbody and equal to the value S/sub 0/=10/sup -19/ W/Hz.cm/sup 2/ at T=300 K and /spl nu/=60 GHz.