US Robotics USR2450 Informacje Techniczne Pobierz pdf (Strona 85)

V 2.2 Copyright SystemExperts 2001,2002,2003

169

Antennas: Basics

n A radiation pattern is a diagram that allows

us to visualize in what directions the energy

will radiate from an antenna

n If an antenna radiates in all directions equally we

say it is an “isotropic radiator”

n The radiation pattern is split into two perpendicular

planes called Azimuth and Elevation

n When RF energy is concentrated, it means the

antenna has “gain” over a portion of the radiator

n gain is measured in decibels and written dBi

V 2.2 Copyright SystemExperts 2001,2002,2003

170

Antennas: Basics (cont.)

n Gaining coverage is achieved thru gain,

which again, is measured in decibels dB

n Calculation range

n Indoors, each 1 dB increase in gain results in a

range increase of 2.5%: outdoors it’s 5%

n Positioning

n Normally should be mounted as high and as clear

as obstructions as possible

n Best performance is when the transmitting and

receiving antenna are at the same height and in

direct line of site

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US Robotics USR2450 Informacje Techniczne Strona 85