Trimble Inc. 6848090 Manual De Usuario
4 Antenna Details
3 8 SNB900 Radio-Modem User Guide
4.1
Omni-Directional Antennas
The SNB900 radio-modem uses an omni-directional antenna. The
antenna concentrates the radio frequency energy that it receives from
the radio-modem and then radiates that energy equally in all directions
in the horizontal plane. The antenna does not increase the energy that
it receives.
antenna concentrates the radio frequency energy that it receives from
the radio-modem and then radiates that energy equally in all directions
in the horizontal plane. The antenna does not increase the energy that
it receives.
Note –
The omni-directional antenna used with the radio-modem is not
omni-directional in the vertical plane. You must orient the antenna
vertically.
vertically.
The degree to which an antenna concentrates radio frequency energy
in one direction is called directivity. Like antenna gain, directivity is
measured in decibels (dB).
in one direction is called directivity. Like antenna gain, directivity is
measured in decibels (dB).
High antenna gain results in high directivity, as more energy is
concentrated and then radiated in the particular plane.
concentrated and then radiated in the particular plane.
4.2
SNB900 Radio-Modem Antenna Range
In an omni-directional antenna, all azimuths receive equal energy, but a
5 dB antenna radiates four times more power in the horizontal plane
than a 0 dB antenna does. In the field, this equates to almost double the
range.
5 dB antenna radiates four times more power in the horizontal plane
than a 0 dB antenna does. In the field, this equates to almost double the
range.
However, it is the elevation and orientation of the rover antenna that
determines which antenna—the 5 dB or the 0 dB antenna—provides
the stronger signal.
determines which antenna—the 5 dB or the 0 dB antenna—provides
the stronger signal.