Models

Table 2-1. Cisco 2.4-GHz Antennas

Cisco offers a number of antennas, and each caters to a different need, a different function, and a different range. The following models are basic types of antennas that you are likely to encounter in your Wi-Fi adventures: Omnidirectional antennas The signal radiates out in a circle from the antenna. That is, a client to the left of the antenna can receive the same signal as a client the same distance away on the right. Directional antennas The signal is focused into a tighter beam and projected a greater distance than the omnidirectional antenna. Although range is increased, the antenna serves only clients in a given direction. Examples of directional antennas include the Yagi antenna, patch antenna, and parabolic dish. Diversity antennas Two antennas reduce multipath distortion. The radio receives a signal on both antennas; however, it transmits on the one with the best signal reception. Note Multipath distortion is covered in greater depth later in this chapter. Antenna Tech Primer Before looking at the models of antennas Cisco offers, it is helpful to understand what the statistics next to each device mean. Beam Width This describes how the signal radiates from an antenna and is expressed in degrees horizontally and vertically. For example, an omnidirectional antenna radiates its signal 360 degrees horizontally. It depends on the model; it might have as much coverage area as 75 degrees vertically. As such, it doesn't radiate its signal in a complete sphere around the antenna. Rather, it's more of a donut shape. This is illustrated in Figure 2-1. Figure 2-1. An Antenna's Beam Width Measures the Horizontal and Vertical Angles at Which a Signal Emanates from the Antenna Gain Gain is a measurement of increase in power, measured in decibels (dB). The decibel scale is logarithmic, and it is used to demonstrate the ratio of one power value to another. The decibel communicates the amount of signal loss or gain within a system. The decibel is somewhat confusing because it is not a concrete measurement, such as meters, kilometers, or kilograms. The decibel is not a measure of signal strength; rather, it's a ratio between two power levels. When power is lost or gained in a system, it does not occur in regular, fixed amounts. Instead, power is lost by varying increments, such as one half, one quarter, and so on. To determine how much loss has occurred, you cannot just add and
Part Number	Type	Description	Beam Width	Gain	Range
AIR-ANT5959	Diversity Omnidirectional	Ceiling-mounted, indoor, diversity antenna. Low profile design makes it inconspicuous.	360 degrees horizontal 80 degrees vertical	2dBi	350 ft. at 1 Mbps 295 ft. at 6 Mbps 130 ft. at 11 Mbps 88 ft. at 54 Mbps
AIR-ANT4941	Omnidirectional	Single dipole antenna providing indoor, omnidirectional coverage.	360 degrees horizontal 65 degrees vertical	2.2dBi	350 ft. at 1 Mbps 300 ft. at 6 Mbps 130 ft. at 11 Mbps 90 ft. at 54 Mbps
AIR-ANT1728	Omnidirectional	Ceiling-mounted, indoor antenna. Unobtrusive, medium-range.	360 degrees horizontal 38 degrees vertical	5.2dBi	497 ft. at 1 Mbps 142 ft. at 11 Mbps
AIR-ANT3213	Diversity Omnidirectional	Pillar-mounted (mounting equipment includes two, six-inch poles that keep the antenna away from the mounting surface), diversity, indoor, medium-range.	360 degrees horizontal 30 degrees vertical	5.2dBi	497 ft. at 1 Mbps 379 ft. at 6 Mbps 142 ft. at 11 Mbps 114 ft. at 54 Mbps
AIR-ANT1729	Patch	Wall-mounted, indoor and outdoor directional patch antenna. Can also be used as a medium-range bridge antenna.	75 degrees horizontal 65 degrees vertical	6dBi	Connected to an AP at 1 Mbps: 542 ft. Connected to an AP at 6 Mbps: 403 ft. Connected to an AP at 11 Mbps: 155 ft. Connected to an AP at 54 Mbps: 121 ft. Connected to a bridge at 11 Mbps: 1900 ft.
AIR-ANT2012	Diversity Patch	Wall-mounted, indoor or outdoor diversity antenna.	80 degrees horizontal 55 degrees vertical	6dBi	547 ft. at 1 Mbps 167 ft. at 11 Mbps
AIR-ANT3549	Patch	Wall-mounted, indoor antenna. Small, unobtrusive design. Can also be used as a medium-range bridge antenna.	60 degrees horizontal 60 degrees vertical	9dBi	Connected to an AP at 1 Mbps: 1700 ft. Connected to an AP at 6 Mbps: 507 ft. Connected to an AP at 11 Mbps: 200 ft. Connected to an AP at 54 Mbps: 153 ft. Connected to a bridge at 11 Mbps: 3390 ft.
AIR-ANT2410Y-R	Yagi	Outdoor directional antenna. Designed as a bridge or for point-to-point communications.	47 degrees horizontal 55 degrees vertical	10dBi	800 ft. at 1 Mbps 548 ft. at 6 Mbps 230 ft. at 11 Mbps 165 ft. at 54 Mbps

Cisco 5-GHz Bridge Antennas

The 5-GHz, 802.11a devices operate at a higher frequency than 802.11b and 802.11g devices. As with the 2.4-GHz devices, Cisco offers a broad range of antennas for unique needs. Table 2-2 compares these models.

Table 2-2. Cisco 5-GHz Bridge Antennas

Part Number	Type	Description	Beam Width	Gain	Range
AIR-ANT58G9VOA-N	Omnidirectional	Used with the Cisco 1400 Wireless Bridge. Nondiversity antenna for outdoor applications.	360 degrees horizontal 6 degrees vertical	9dBi	8 miles at 9 Mbps 2 miles at 54 Mbps
AIR-ANT58G10SSA-N	Sector	Used with the Cisco 1400 Wireless Bridge. Nondiversity antenna for outdoor applications.	60 degrees horizontal 60 degrees vertical	9.5dBi	8 miles at 9 Mbps 2 miles at 54 Mbps
AIR-ANT58G28SDA-N	Dish	Used with the Cisco 1400 Wireless Bridge. Nondiversity antenna for outdoor applications. Designed for use at the client sites of a point-to-point or point-to-multipoint deployment.	5.7 degrees horizontal 6 degrees vertical	28dBi	23 miles at 9 Mbps 12 miles at 54 Mbps

Cisco 2.4-GHz Bridge Antennas

The bridges that work in the 2.4-GHz bands (like the Cisco 1300) have their own line of antennas. Table 2-3 compares these antennas.

Table 2-3. Cisco 2.4-GHz Bridge Antennas

Part Number	Type	Description	Beam Width	Gain	Range
AIR-ANT2506	Omnidirectional mast mount	Outdoor, short-range, point-to-multipoint connections.	360 degrees horizontal 38 degrees vertical	5.2dBi	3.3 miles at 2 Mbps 1.66 miles ft. at 11 Mbps .21 miles at 54 Mbps
AIR-ANT24120	High-gain omnidirectional mast mount	Outdoor, medium-range, point-to-multipoint connections.	360 degrees horizontal 7 degrees vertical	12dBi	15.83 miles at 2 Mbps 7.92 miles at 11 Mbps 1 mile at 54 Mbps
AIR-ANT2414S-R	Vertically polarized sector	Outdoor, long-range, point-to-multipoint connections.	90 degrees horizontal 8.5 degrees vertical	14dBi	16.71 miles at 2 Mbps 8.89 miles at 11 Mbps 1.26 miles at 54 Mbps
AIR-ANT1949	Yagi mast mount	Outdoor, medium-range, directional connections.	30 degrees horizontal 25 degrees vertical	13.5dBi	18.33 miles at 2 Mbps 11.19 miles at 11 Mbps 1.41 miles at 54 Mbps
AIR-ANT3338	Solid dish	Outdoor, long-range, directional connections.	12.4 degrees horizontal 12.4 degrees vertical	21dBi	26.49 miles at 2 Mbps 20.1 miles at 11 Mbps 4.46 miles at 54 Mbps