Datasheet

Reference Guide
© 2009 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information. Page 7 of 63
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Small Office/Small Retail: The standard dipole may provide adequate coverage in these
areas depending on the location of the radio device. However, in a back corner office a
patch antenna may provide better coverage. It can be mounted to the wall above most
obstructions for best performance. Coverage of this type antenna depends on the
surrounding environment.
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Enterprise/Large Retail: In most cases, these installations require a large coverage area.
Experience has shown that omnidirectional antennas mounted just below the ceiling girders
or just below the drop ceiling typically provide the best coverage (this will vary with stocking,
type of material, and building construction). The antenna should be placed in the center of
the desired coverage cell and in an open area for best performance. In cases where the
radio unit will be located in a corner, or at one end of the building, a directional antenna
such as a patch or yagi can be used for better penetration of the area. Also, for areas that
are long and narrow—such as long rows of racking—a directional antenna at one end may
provide better coverage. The radiation angle of the antennas will also affect the coverage
area.
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Point-to-Point: When connecting two points together (such as a wireless bridge), the
distance, obstructions, and antenna location must be considered. If the antennas can be
mounted indoors and the distance is very short (several hundred feet), the standard dipole
or mast mount 5.2 dBi omnidirectional may be used. An alternative is to use two patch
antennas. For very long distances (1/2 mi. or more), directional high-gain antennas must
be used. These antennas should be installed as high as possible, and above obstructions
such as trees, buildings, and so on; and if directional antennas are used, they must be
aligned so that their main radiated power lobes are directed at each other. With a line-of-
site configuration, distances of up to 25 miles at 2.4 GHz and 12 miles at 5 GHz can be
reached using parabolic dish antennas, if a clear line-of-site is maintained. With the use of
directional antennas, fewer interference possibilities exist and there is less possibility of
causing interference to anyone else.
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Point-to-Multipoint Bridge: In this case (in which a single point is communicating to
several remote points), the use of an omnidirectional antenna at the main communication
point must be considered. The remote sites can use a directional antenna that is directed at
the main point antenna.
Cabling
As stated above, cabling introduces losses into the system, negating some of the gain an antenna
introduces and reducing range of the RF coverage.
Interconnect Cable
Attached to all antennas (except the standard dipoles), this cable provides a 50 Ohm impedance to
the radio and antenna, with a flexible connection between the two items. It has a high loss factor
and should not be used except for very short connections (usually less than 10 feet). Typical
length on all antennas is 36 in. (or 12 in. on some outdoor antennas).
Low-Loss/Ultra-Low-Loss Cable
Cisco offers two styles of cables for use with the 2.4 GHz and 5 GHz product line. These cables
provide a much lower loss factor than standard interconnect cable, and they can be used when the
antenna must be placed at any distance from the radio device. While these are low-loss cables,
they should still be kept to a minimum length. There are two types of cable supplied by Cisco for