ELECTROMAGNETIC SPECTRUM BIOMEDICAL ENGINEERING TAE_EUI, KIM

Electromagnetic Spectrum ① Audio freq. ② Radio freq. ③ Microwave ④ Infrared ⑤ Visible light ⑥ Ultraviolet ⑦ X-ray ⑧ R-ray

① Audio frequency 20~20,000Hz; long wave length No change with respect to area or position Because it’s too low freq. long wave length to neglect ( diameter of the earth) Independent on position ECG bit overlapped, similar to the range of EMG. EEG is lower than 20HzNo sound from speaker

② Radio frequency 1)Low freq.:30kHz ~ 300kHz (10km ~ 1km) 2)Medium freq.:300kHz ~ 3MHz (1km ~ 100m)

3)High freq.:3MHz ~ 30MHz (100m ~ 10m) ② Radio frequency 1 period delayed 90 delay

② Radio frequency 3)High freq.:3MHz ~ 30MHz (100m ~ 10m) Able to describe magnitude of each wave at the same time. WAVE PROPAGATION In high frequency range, as circuits get bigger, we cannot say it is a same signal. Possible to adjust Circuit Analysis within 1M (Low freq.) whereas not to adjust Circuit Analysis over 1M (High freq.) Differentiate by means of time The length of antenna should be longer than half of wave length. The reason to try to use high Freq. Antenna can be shorter.

② Radio frequency 4)Very High freq. (VHF) : 30MHz ~ 300MHz (10m ~ 1m) Ex) TV 5)Ultra High freq. (UHF) : 300MHz ~ 3GHz (1m ~ 0.1m) Ex) Mobile

③ Microwave 1)Centimeter Wave : 3GHz ~ 30GHz (10cm ~ 1cm);Heavily Comm. Ex) Satellite 2)Millimeter Wave : 30GHz ~ 300GHz (10mm ~ 1mm);High comm. 3)Sub-millimeter Wave : 300GHz ~ 3THz ( 1mm ~ 0.1mm );Not so much

④ Infrared 1)Far infrared : 2)(Intermediate)Infrared :

⑤ Visible light Red (Longest ) Violet (Shorter ) Reflect our body

⑥ Ultraviolet ⑦ X - ray ⑧ R - ray Penetrate through our body Plank constant Energy

In summary : hundreds nm (Visible light) : tens um (Infrared light) Things emit electromagnetic Temp. of hands :

Radiation Thermometer ShutterLensIR Sensor Pyroelectric Sensor Thermometer Radiation Thermometer