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Copyright © 2017 Linx Technologies

159 Ort Lane, Merlin, OR 97532

Phone: +1 541 471 6256

Fax: +1 541 471 6251

www.linxtechnologies.com

by

ANT-2.4-ID Data Sheet

About Gain Plots

The true measure of the effectiveness of an antenna in any given application is determined by the gain

and radiation pattern measurement. For antennas gain is typically measured relative to a perfect (isotropic)

radiator having the same source power as the antenna under test, the units of gain in this case will be

decibels isotropic (dBi). The radiation pattern is a graphical representation of signal strength measured at

fixed distance from the antenna.

Gain when applied to antennas is a measure of how the antenna radiates and focuses energy into free

space. Much like a flashlight focuses light from a bulb in a specific direction, antennas focus RF energy into

specific directions. Gain in this sense refers to an increase in energy in one direction over others.

It should also be understood that gain is not “free”, gain above 0dBi in one

direction means that there must be less gain in another direction. Pictorially

this can be pictured as shown in the figures to the right. The orange pattern

represents the radiation pattern for a perfect dipole antenna, which is shaped

like a donut. The pattern for an omnidirectional antenna with gain is shown in

blue. The gain antenna is able to work with a device located further from the

center along the axis of the pattern, but not with devices closer to the

center when they are off the axis – the donut has been squished.

Gain is also related to the overall physical size of the antenna, as well as

surrounding materials. As the geometry of the antenna is reduced below the effective wavelength (considered

an electrically small antenna) the gain decreases. Also, the relative distance between an electrically small

antenna and its associated ground impacts antenna gain.

Gain Plots

-60.00

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XZ-Plane Gain

YZ-Plane Gain

XY-Plane Gain

E / Vertical Gain

H / Horizontal Gain

Total Gain

X

Y

Z

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Y

Z