F band, from 3GHz to 30GHz) suffer greatly from adverse weather conditions, particularly precipitation. This problem is Wavelength Wavelength Wavelength Figure 13.1 Wavelength Chapter 13 Wireless Communications Basics Table 13.1 Radio Spectrum Class of Frequency (Abbrev.) Frequency Wavelength Key Applications Extremely low (ELF) <3Hz-30Hz 100,000-10,000 km Communication with submarines Super low (SLF) 30Hz-300Hz 10,000-1,000 km Communication with submarines Ultra low (ULF) 300Hz-3KHz 1,000-100 km Communication within mines Very low (VLF) 3KHz-30KHz 100-10 km Submarine communica- tion, avalanche beacon- ing, wireless heart rate monitoring Low (LF) 30KHz-300KHz 10-1 km Navigation, time signal- ing, AM long-wave broadcasting Medium (MF) 300KHz-3MHz 1,000-100 m AM medium-wave broadcasting High (HF) 3MHz-30MHz 100-10 m Short-wave broadcasting and amateur radio Very high (VHF) 30MHz-300MHz 10-1 m FM and television broadcasting Ultrahigh (UHF) 300MHz-3GHz 100-10 cm Television broadcasting, mobile phones, WLANs, and ground-to-air and air- to-air communications Super high (SHF) 3GHz-30GHz 10-1 cm Microwave devices, mobile phones (W-CDMA), WLANs, and most modern radars Extremely high (EHF) 30GHz-300GHz 1-0.1 cm Radio astronomy, high- speed microwave radio relay Wireless Communications Regulations Issues even greater in the extremely high frequencies (EHF band, from 30GHz to 300GHz). Above 300GHz, the earth's atmosphere greatly absorbs electromagnetic radiation, rendering the atmosphere basically opaque to higher frequencies of electromagnetic radiation, until it once again becomes transparent in the infrared and optical fre- quency ranges. Beyond EHF, no class of frequency or ITU band is specified, but in the frequen- cies above 300GHz, the wavelengths are smaller than 1 mm. One application for this region is night vision. The majority of wireless data applications today are therefore handled in the band between 2GHz and 6GHz (the UHF and SHF bands). However, there is also great interest in making use of the higher bands, 