The basic factors of the human body's various physiological reactions caused by ultrashort wave are thermal effect and non-thermal effect.

Because the human body is a composite tissue with electrical conductors and dielectrics, under the action of ultrashort waves, conduction current and displacement current are formed in the body at the same time. Due to its higher frequency, the resistance of the dielectric is getting smaller and smaller. When ultrashort wave treatment is formed, the displacement current component is dominant, and the dielectric loss is mainly used to generate heat. But when the frequency is extremely high, the dipole has no time to rotate or the rotation amplitude is extremely small, so that the dielectric loss is reduced and the heat production is reduced. This shows that the proportional relationship between the heat generation and the increase in frequency is only applicable to the oscillation frequency within a certain range. This displacement current generates heat in order to overcome the resistance of the medium, and the size of the medium loss is closely related to the dielectric constant of the tissue. Because the difference in the dielectric constant of various tissues in the human body is small, the heat distribution generated under the action of ultrashort waves is compared Evenly.

However, in the ultrashort wave capacitive electric field treatment, because there are fewer blood vessels in the fat layer, the heat is not easily taken away by the blood flow. Therefore, its temperature is higher than the muscles with rich blood supply. According to the measurement, when the ultrashort wave with a wavelength of 7.34 meters acts, the temperature of the fat rises and the muscles The ratio of heating up to 8:1 still has the disadvantage of overheating of fat. In actual treatment, the temperature of the deep tissue can be increased by adjusting the distance between the skin and the electrode plate, and the temperature of the skin and subcutaneous fat can be reduced.

Non-thermal effect. Organisms high in the ultra-high frequency capacitance electric field are affected by the potential difference voltage. The ultra-high-frequency electric oscillation wave causes the resonance of the intracellular material, causing the change of the surface tension of the liquid, the surface tension of some substances increases, and the Surface tension is reduced. When high-frequency alternating high-frequency electromagnetic waves act, when the intensity of the electric field is maximum, the cell is stretched in the direction of the electric field, and the moment of the minimum field strength is restored to its original state. The electric field of the appropriate frequency can make the cells fully expand and contract, produce special stimulation to the cells and tissues, and cause special biological effects.

Ultra-short wave is especially used in low-intensity action, and the current temperature can not be measured by all methods, the biological effect is still very obvious, but the same conditions of external heat effect has no similar effect. For example, when the short-term no-heat ultrashort wave is applied to the human body, the resolution of acute inflammation is more obvious than the long-term warm-heat effect. In addition, it can also cause reactions in other tissues and organs, collectively known as non-thermal effects. It is found that this non-thermal effect is particularly obvious when the low field strength (40mw/cm2 or less) is applied. When the high-intensity effect is applied, this special effect is masked by the thermal effect.