Smart Phone and Next Generation Mobile Computing

Supporting Wireless Technologies 101

frequency (MF), high frequency (HF), very high frequency (VHF),

ultra-high frequency (UHF), super-high frequency (SHF), extremely

high frequency (EHF), infrared, visible light, ultraviolet, x-ray,

gamma-ray, and cosmic ray, each of which represents a frequency

band. Figure 3.1 shows the frequency spectrum up to the visible

light band. Notice that in the context of electronic communication,

there are two categories of transmission medium: guided medium

(e.g., copper coaxial cable and twisted pair) and unguided medium

(for wireless communication in the air). The guided medium car-

ries signals or waves between a transmitter and a receiver, whereas

the unguided medium typically carries wireless signals between an

antenna ...