Applications of Microwave Engineering
The majority of today’s applications of RF and microwave technology are to wireless networking and communications systems, wireless security systems, radar systems, environmental remote sensing, and medical systems.
Modern wireless telephony is based on the concept of cellular frequency reuse, a technique first proposed by Bell Labs in 1947 but not practically implemented until the 1970s.
By this time advances in miniaturization, as well as increasing demand for wireless communications,drove the introduction of several early cellular telephone systems in Europe, the United States, and Japan.
The Nordic Mobile Telephone (NMT) system was deployed in 1981 in the Nordic countries, the Advanced Mobile Phone System (AMPS) was introduced in the United States in 1983 by AT&T, and NTT in Japan introduced its first mobile phone service in 1988.
Modern wireless telephony is based on the concept of cellular frequency reuse, a technique first proposed by Bell Labs in 1947 but not practically implemented until the 1970s.
By this time advances in miniaturization, as well as increasing demand for wireless communications,drove the introduction of several early cellular telephone systems in Europe, the United States, and Japan.
The Nordic Mobile Telephone (NMT) system was deployed in 1981 in the Nordic countries, the Advanced Mobile Phone System (AMPS) was introduced in the United States in 1983 by AT&T, and NTT in Japan introduced its first mobile phone service in 1988.
All of these early systems used analog FM modulation, with their allocated frequency bands divided into several hundred narrow band voice channels.
These early systems are usually referred to now as first-generation cellular systems, or 1G. Second-generation (2G) cellular systems achieved improved performance by using various digital modulation schemes, with systems such as GSM, CDMA, DAMPS, PCS, and PHS being some of the major standards introduced in the 1990s in the United States, Europe, and Japan. These systems can handle digitized voice, as well as some limited data, with data rates typically in the 8 to 14 kbps range.
In recent years there has been a wide variety of new and modified standards to transition to handheld services that include voice, texting, data networking, positioning, and Internet access.
These early systems are usually referred to now as first-generation cellular systems, or 1G. Second-generation (2G) cellular systems achieved improved performance by using various digital modulation schemes, with systems such as GSM, CDMA, DAMPS, PCS, and PHS being some of the major standards introduced in the 1990s in the United States, Europe, and Japan. These systems can handle digitized voice, as well as some limited data, with data rates typically in the 8 to 14 kbps range.
In recent years there has been a wide variety of new and modified standards to transition to handheld services that include voice, texting, data networking, positioning, and Internet access.
These standards are variously known as 2.5G, 3G, 3.5G, 3.75G, and 4G, with current plans to provide data rates up to at least 100 Mbps. The number of subscribers to wireless services seems to be keeping pace with the growing power and access provided by modern handheld wireless devices; as of 2010 there were more than five billion cell phone users worldwide.
Satellite systems also depend on RF and microwave technology, and satellites have been developed to provide cellular (voice), video, and data connections worldwide. Two large satellite constellations, Iridium and Globalstar, were deployed in the late 1990s to provide worldwide telephony service.
Satellite systems also depend on RF and microwave technology, and satellites have been developed to provide cellular (voice), video, and data connections worldwide. Two large satellite constellations, Iridium and Globalstar, were deployed in the late 1990s to provide worldwide telephony service.