Cisco Cisco Catalyst 6000 Multilayer Switch Feature Card MSFC2 White Paper
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When an environment requires the use of directional antennas, the complexity of the design and the
implementation both will go up accordingly. It should, however, also be noted that outstanding results can be
achieved.
Channel Reuse and Directional Antennas
If mounting on the ceiling in an auditorium with high ceilings greater than 25 feet, it is recommended that high gain
directional patch or Yagi style MIMO antennas be used because these antennas provide:
●
Better ceiling to floor coverage, if mounted in the ceiling or on catwalks with antennas oriented in a direct
downward direction. This creates smaller cells of coverage directly beneath the APs and allows for better
channel isolation between adjacent cells while maintaining power levels and sensitivity in the direction of
the covered clients.
●
Coverage in larger venues with very high ceilings or perhaps where ceiling access is not available. Placing
directional antennas at mid level from the sides or from behind the coverage zone and using downtilt can
provide controllable coverage zones and better installation options in difficult environments.
●
A much narrower coverage lobe or beam, thus allowing smaller cells so the number of cells and channels
for both 2.4 GHz and 5 GHz can occupy a common room providing increased cell isolation and reducing
CCI. This is critical in any environment where the design solution requires channel reuse for either band.
Directional antennas like omnidirectional antennas are classified by their 3 dB beamwidth in the horizontal and
elevation planes. But directional antennas typically have much higher gain than an antenna that is classified as
omnidirectional. For example, the AIR-ANT2460NP-R antenna, Table 7, has a 3 dB horizontal beamwidth of 80°
and a 75° elevation plane. This is quite useful in isolating the AP and antenna from surrounding energy and
providing better coverage in the intended zone.
Table 7.
6 dBi Patch, Three Element Wall Mount
6 dBi Patch, Three Element Wall Mount AIR-ANT2460NP-R
Antenna A Radiation Pattern
Antenna B Radiation Pattern
Antenna C Radiation Pattern
Frequency Range
2402-2484 MHz
VSWR
2.1
Gain
6 dBi