ProSoft Technology RLX-IFH24S-A - Manual (Page 73)

RLX-IFHS ♦ RadioLinx Industrial Wireless Guide to the RLX-IFHS User Manual
RadioLinx® Industrial Frequency Hopping Serial Radios User Manual
ProSoft Technology, Inc. Page 73 of 107
November 19, 2013
4.1.2 Antenna Pattern
Information between two wireless devices is transferred via electromagnetic
energy radiated by one antenna and received by another. The radiated power of
most antennas is not uniform in all directions and has varying intensities. The
radiated power in various directions is called the pattern of the antenna. Each
antenna should be mounted so that its direction of strongest radiation intensity
points toward the other antenna or antennas with which it will exchange signals.
Complete antenna patterns are three-dimensional, although often only a two-
dimensional slice of the pattern is shown when all the antennas of interest are
located in roughly the same horizontal plane, along the ground rather than above
or below one another.
A slice taken in a horizontal plane through the center (or looking down on the
pattern) is called the azimuth pattern. A view from the side reveals a vertical
plane slice called the elevation pattern.
An antenna pattern with equal or nearly equal intensity in all directions is
omnidirectional. In two dimensions, an omnidirectional pattern appears as a
circle (in three dimensions, an omnidirectional antenna pattern would be a
sphere, but no antenna has true omnidirectional pattern in three dimensions). An
antenna is considered omnidirectional if one of its two dimensional patterns,
either azimuth or elevation pattern, is omnidirectional.
Beamwidth is an angular measurement of how strongly the power is
concentrated in a particular direction. Beamwidth is a three dimensional quantity
but can be broken into two-dimensional slices just like the antenna pattern. The
beamwidth of an omnidirectional pattern is 360 degrees because the power is
equal in all directions.
4.1.3 Antenna Gain
Antenna gain is a measure of how strongly an antenna radiates in its direction of
maximum radiation intensity compared to how strong the radiation would be if the
same power were applied to an antenna that radiated all of its power equally in
all directions. Using the antenna pattern, the gain is the distance to the furthest
point on the pattern from the origin. For an omnidirectional pattern, the gain is 1,
or equivalently 0 dB. The higher the antenna gain is, the narrower the
beamwidth, and vice versa.
The amount of power received by the receiving antenna is proportional to the
transmitter power multiplied by the transmit antenna gain, multiplied by the
receiving antenna gain. Therefore, the antenna gains and transmitting power can
be traded off. For example, doubling one antenna gain has the same effect as
doubling the transmitting power. Doubling both antenna gains has the same
effect as quadrupling the transmitting power.