Cisco Aironet 1520 Series Uživatelský manuál stáhnout pdf (Strana 7)

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.

●

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.

●

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 lines. 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 mounting the antenna away from the radio unit. The 100- and

150-foot cables are LMR600 type cable, while the 20- and 50-foot cables are LMR400 type cables. All four lengths

are supplied with one RP-TNC plug and one RP-TNC jack connector attached. This allows for connection to the

radio unit and to the interconnect cable supplied on the antennas.

Connectors

According to the U.S. Federal Code of Regulations, products used in the 2.4- and 5-GHz ISM bands manufactured

after June 1994 must either use connectors that are unique and nonstandard (meaning not readily available on the

market by the average user) or be designed to be professionally installed (“professional” here indicates a person

trained in RF installation and regulations). Since many of the 2.4-GHz products are installed by non-RF trained

personnel, these products must comply with the unique connector ruling. The Cisco outdoor access and bridge

products are designed for installation by a RF professional, and therefore may use a standard N style connector.

Cisco Aironet indoor products use reverse polarity-TNC (RP-TNC) connectors. While they are similar to the normal

TNC connectors, they cannot be mated to the standard connectors.

To ensure compatibility with Cisco Aironet products, use antennas and cabling from Cisco.

1 2 3 4 5 6 7 8 9 10 11 12 ... 72 73

Komentáře k této Příručce

Žádné komentáře

Cisco Aironet 1520 Series Uživatelský manuál Strana 7

Komentáře k této Příručce

Související produkty a manuály pro Přístupové body WLAN Cisco Aironet 1520 Series