Afar AR-24010E, Operator'S Manual

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pulsAR radio Operator's Manual
6 RF LINK DESIGN
6.1 Antenna Selection
The pulsAR radio comes equipped with two antenna ports to connect to external antennas. The two
ports are typically used with the Mesh/Tree network topology described in section 2. Afar carries the
following antennas which cover the needs of most typical applications.
Band Antenna Type Gain AFAR Model Number
900 MHz
Omni-directional 5 dBi ATO-0905
Yagi 9 dBi ATD-0909
Dish Reflector 15 dBi ATD-0915
2.4 GHz
Omni-directional 9 dBi ATO-2409
Panel 16 dBi ATD-2416
Panel 19 dBi ATD-2419
Dish Reflector 24 dBi ATD-2424
The “gain” of the antenna is a measurement of how much it focuses its radiated energy in a specific
direction or plane. An “omni-directional” antenna for example radiates its energy over 360 degrees in
the horizontal plane but has a much poorer radiation in the vertical plane. In most applications you
don’t need to radiate vertically (into the sky or into the ground) so by focusing the energy in the
horizontal plane you achieve a reasonable gain.
Omni-directional antennas are a good choice for a hub radio in a point-to-multipoint application when
the remote radios are all around. If the remote radios happen to be all located in one particular
“sector” when viewed from the hub location then you can use a “sectorial” antenna that focuses the
energy in that general direction. There are antennas that cover sectors with different angles, for
example, 30, 60, 90 and 120 degrees. The narrower the angle the higher the gain of the sectorial
antenna.
At fixed remote radios, or in a point-to-point link, you should select high gain directional antennas
that focus all the radiated energy in one specific direction. These antennas not only provide a much
higher gain and therefore increased radio ranges and link margins, but also protect your link from
unwanted interference coming from other directions.
In mobile applications you typically need omni-directional antennas on the moving vehicle so that the
vehicle can change its orientation and stay connected to say, a fixed hub.
6-1