A1-Electromagnetic signals

=⌘TOC on A1-Electromagnetic signals =

=⌘ Wave Propagation Parameters =

Can also be called "Propagation constant". Somewhat misleading, as the propagation usually varies strongly.

Alternative names:


 * Transmission parameters
 * Propagation parameters
 * Propagation coefficients
 * Transmission constants
 * Secondary coefficients

Propagation constant, symbol γ, is defined by the ratio between the amplitude at the source, and the amplitude at some distance x. Is a complex quantity, so we use α (attenuation constant) and β (phase constant) to define it. Attenuation constant, is the loss of signal, or attenuation of an electromagnetic wave travelling through a medium. Phase constant is the change in phase per meter, along the path travelled.

=⌘Wave propagation and absorption mechanisms=

The frequencies which we use for mobile communications are ranging from 450 MHz (ICE), the old TV bands, 800-900 MHz (GSM), 1800 (GSM), 1900, 2100 MHz (UMTS), 2400 MHz (Wifi), 2650 MHz (LTE), and 5100 MHz (IEEE802.11a..). While previously frequency band were used for a specific technology, refarming started in 2012 to open for communication technologies in other bands. Examples of such refarming are LTE1800 indicating an operation of LTE in the 1800 band. Back in 2013 Apple surprised the European operators, as the iPhone came with LTE only in the 1800 band, and not, as usual in Europe, in the 2600 band.

(Source:http://en.wikipedia.org/wiki/Radio_propagation)

=⌘ Further readings =
 * see Wave Propagation Parameters (by Joachim Tingvold)

=⌘ What will we learn today =


 * basics of radio communication
 * sampling theorem
 * typical radio transmission
 * what effects the signal strengths

=⌘ Heinrich Hertz - Radiowave propagation =

=⌘ Electromagnetic signals =

Literature:

 * Andersen, J.B., "Propagation measurements and models for wireless communications channels"
 * Simon Saunders, Alejandro Aragón-Zavala, "Antennas and propagation for wireless communication systems"
 * Seybold, J. S., "Introduction to RF Propagation"
 * Andreas F. Molisch, "Wireless Communications"
 * Andrea Goldsmith, "Wireless Communications"
 * Shigekazu Shibuya, "A basic atlas of radio-wave propagation"

Keywords used:


 * wireless electromagnetic propagation
 * wireless electromagnetic propagation parameter
 * wireless electromagnetic propagation fading
 * wireless propagation refraction
 * wireless wave attenuation constant