Models


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

Table 2-1. Cisco 2.4-GHz Antennas

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





Cisco 802.11 Wireless Networking Quick Reference
Cisco 802.11 Wireless Networking Quick Reference
ISBN: 158705227X
EAN: 2147483647
Year: 2005
Pages: 126

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