Cisco AIR-ANT24120 Mast Mount Outdoor High Gain AntennaThe Cisco AIR-ANT24120 antenna was designed for WLAN applications for frequencies of 2400-2500 MHz. The AIR-ANT24120 antenna is omni directional and has a nominal gain of 12 dBi. This design uses an elevated center-feed to produce an elevation pattern with very little "squint" or beam-tilt.
Cisco AIR-ANT24120 Mast Mount Outdoor High Gain Antenna with RP-TNC ConnectorThe Cisco AIR-ANT24120 is designed to be mounted on a round mast as well as perform in a variety of environments. Implementing the antenna system can greatly improve coverage and performance. To optimize the overall performance of a Cisco wireless LAN, it is important to understand how to maximize radio coverage with the appropriate antenna selection and placement. An antenna system comprises numerous components, including the antenna, mounting hardware, connectors, antenna cabling, and in some cases, a lightning arrestor.
The Cisco Aironet product lines utilize both the 2.4- and 5-GHz bands. In the United States, three bands are defined as unlicensed and known as the ISM bands. The ISM bands are as follows:
- 900 MHz (902-928 MHz)
- 2.4 GHz (2.4-2.4835 GHz) IEEE 802.11b
- 5 GHz (5.15-5.35 and 5.725-5.825 GHz) IEEE 802.11a, HIPERLAN/1 and HIPERLAN/2. This band is also known as the UNII band, and has 3 sub-bands, UNII1 (5.150-5.250 GHz), UNII2 (5.250-5.350 GHz) and UNII3 (5.725-5.825 GHz)
Each range has different characteristics. The lower frequencies exhibit better range, but with limited bandwidth and hence lower data rates. The higher frequencies have less range and are subject to greater attenuation from solid objects.
An antenna gives the wireless system three fundamental properties, gain, direction, and polarization. Gain is a measure of increase in power. Direction is the shape of the transmission pattern. A good analogy for an antenna is the reflector in a flashlight. The reflector concentrates and intensifies the light beam in a particular direction similar to what a parabolic dish antenna would to a RF source in a radio system.
Antenna gain ratings are in decibels which is a ratio between two values. An antenna rating is typically to the gain of an isotropic or dipole antenna. An isotropic antenna is a theoretical antenna with a uniform three-dimensional radiation pattern (similar to a light bulb with no reflector). dBi is used to compare the power level of a given antenna to the theoretical isotropic antenna. The U.S. FCC uses dBi in its calculations. An isotropic antenna is said to have a power rating of 0 dB; for example, zero gain/loss when compared to itself.
Unlike isotropic antennas, dipole antennas are real antennas (dipole antennas are standard on Cisco Aironet access points, base stations, and workgroup bridges). Dipole antennas have a different radiation pattern compared to isotropic antennas. The dipole radiation patter