band (UWB), IEEE 802.15.4 ZigBee, and some applications of RFID. WPANs are discussed further in Chapter 15. As you can see, microwave is truly the workhorse of the wireless world. Part IV of this book therefore dedicates much attention to its variations. Satellite In May 1946, Project RAND released Preliminary Design of an Experimental World- Circling Spaceship, which stated, "A satellite vehicle with appropriate instrumenta- tion can be expected to be one of the most potent scientific tools of the Twentieth Century. The achievement of a satellite craft would produce repercussions compa- rable to the explosion of the atomic bomb." In 1947, Arthur C. Clarke (well known for his science fiction, particularly 2001: A Space Odyssey) presented a paper to the scientific community in which he suggested that if we explored orbits in higher elevations above the earth, we might achieve an orbit at which a satellite would be able to serve as a communications broadcast tool. Until that point, we were begin- ning early explorations of satellites, but they were what we today would call low- earth-orbit satellites, which means they were at relatively low altitudes over the earth and revolved around the earth much faster than the earth rotates on its own Chapter 2 Traditional Transmission Media axis. Clarke theorized that if we sent a satellite into a higher orbit, it would encounter a geosynchronous orbit, meaning that the satellite would rotate around the earth at exactly the same rate at which the earth rotates on its axis; the orbiting device would appear to hang stationary over a given point on earth. Clarke's hypotheses were supported and thus began the development of the communica- tions sector for the space industry. The first artificial satellite was Sputnik 1, launched by the Soviet Union on October 4, 1957. In the United States, NASA launched the first experimental com- munications satellite in 1963. The first commercial communications satellite was launched two years later, SO 1965 marked the beginning of the use of s