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Directivity. In electromagnetics, directivity is a parameter of an antenna or optical system which measures the degree to which the radiation emitted is concentrated in a single direction. It is the ratio of the radiation intensity in a given direction from the antenna to the radiation intensity averaged over all directions. [ 1] Therefore, the ...
Friis' original idea behind his transmission formula was to dispense with the usage of directivity or gain when describing antenna performance. In their place is the descriptor of antenna capture area as one of two important parts of the transmission formula that characterizes the behavior of a free-space radio circuit. [2]
Omnidirectional antenna. In radio communication, an omnidirectional antenna is a class of antenna which radiates equal radio power in all directions perpendicular to an axis ( azimuthal directions), with power varying with angle to the axis ( elevation angle ), declining to zero on the axis. [ 1][ 2] When graphed in three dimensions (see graph ...
Operating margin. In business, operating margin —also known as operating income margin, operating profit margin, EBIT margin and return on sales ( ROS )—is the ratio of operating income ("operating profit" in the UK) to net sales, usually expressed in percent. Net profit measures the profitability of ventures after accounting for all costs.
Link budget. A link budget is an accounting of all of the power gains and losses that a communication signal experiences in a telecommunication system; from a transmitter, through a communication medium such as radio waves, cable, waveguide, or optical fiber, to the receiver. It is an equation giving the received power from the transmitter ...
Marchant Calculating Machine Company. The Marchant Calculating Machine Company was founded in 1911 by Rodney and Alfred Marchant in Oakland, California . The company built mechanical, and then electro mechanical calculators which had a reputation for reliability. First models were similar to the Odhner arithmometer.
Link margin. In a wireless communication system, the link margin (LKM) is a critical parameter that measures the reliability and robustness of the communication link. It is expressed in decibels (dB) and represents the difference between the minimum expected power received at the receiver's end and the receiver's sensitivity.
Okumura developed a set of curves giving the median attenuation relative to free space (A mu), in an urban area over a quasi-smooth terrain with a base station effective antenna height (hte) of 200 m and a mobile antenna height (hre) of 3 m. These curves were developed from extensive measurements using vertical omni-directional antennas at both ...