Table 6.2 Microwave Safety Standards in the USA, _______ _______Former USSR and Canada ____________ Thermal Effect of Microwaves There has been much reported about thermal microwave effects on the human body using numerical analysis on ideal models [Tell, R.A., 1972], As an example, here we show one of those results based on the multi-layer human tissue model. 1) < 150 MHz Living tissue is almost transparent to this electromagnetic wave. 2) 150 MHz-1 GHz Penetration depth into animal tissue is more than 2 cm. For those large animals like human, most of the energy is converted to heat in deep part of its body. The small animals suffer fewer effects than large animals. 3) 1 GHz-3 GHz This kind of electromagnetic wave is absorbed in the tissue 1-2 cm, 3-4 cm and 5-6 cm depth. There appears to be a periodic absorption peak depending on the wavelength and the property of the skin. The tissues with a high concentration of water absorb the microwave energy well. As the bone works as a reflector of the electromagnetic wave, the water rich tissue near to bone is easily heated. 4) 3 GHz< Most of the energy is converted to heat at the body surface, i.e., at the skin. As the wavelength shortens, its effects show more resemblance to the effects of the infrared beam and the visible laser beam. As the microwaves of number 3) or 4) has the highest possibility to be used in the power transmission system at present stage, we must be careful of their properties. Effects upon Whole Body Irradiation The ability of electromagnetic modeling of an animal body is very restricted because of its extreme complexity. If you intend to model the whole of an animal body, you must deal not only with its physical structure but also with the intrinsic protective and compensatory reaction mechanisms in the body. However, it is impossible at the present stage. Therefore we should observe the real effects of microwaves on real living organisms. Unfortunately, there are few reports using a microwaves of more than 10 GHz frequency.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==