Psiber Data Systems RF3D 2.4.1 Omnidirectional Antennas , 2.4.2 Patch Antennas , 2.4.3 Yagi Antennas , 2.5 Attenuation, 2.6 Theoretical Throughput Rates

manual

2.4.1 Omnidirectional Antennas Omnidirectional antennas are generally used to in-

crease the communication range within ofﬁces or homes. The antennas commonly sup-

plied with access points are omnidirectional. Omnidirectional antennas have a beam

angle of 360° in the horizontal plane. Vertically, their radiation pattern is compressed, and

may cover an angle of 80°. These antennas can have a gain of 2 to 5 dB, and may be

used to increase an access point’s horizontal range.

Please see appendix A: The Antenna Library

2.4.2 Patch Antennas Patch antennas typically offer gain of 4 to 6 dB, with horizontal

and vertical beam angles of 80° to 65°. A patch antenna can increase the communica-

tion range by up to 100%.

2.4.3 Yagi Antennas Yagi antennas are extremely directional antennas, and are used

to set up point-to-point radio links, bridging distances of up to 300 m at 54 Mbit/s, 1 km

at 11 Mbit/s, or 2 km at 2 Mbit/s for example using 2.4 GHz WLAN. In this way separate

buildings can be interconnected using WLAN equipment.

Please see appendix A: The Antenna Library

2.5 Attenuation

Once the signal leaves the access point’s antenna, it is subject to attenuation, or loss: that

is, it becomes weaker. In the ideal case, the signal attenuation with increasing distance

from the antenna is called free-space loss. The theoretical rate of free space loss is different

for the different frequency bands, 2.4 GHz and 5 GHz. A 5 GHz signal is subject to greater

loss than a 2.4 GHz signal. Indoors , the actual attenuation depends on the given build-

ing. The signal loss through wooden walls is clearly different from the loss through stone or

reinforced concrete. It is therefore important to determine the building materials involved

and their speciﬁc properties.

Please see appendix B: The Wall and Floor Library

2.6 Theoretical Throughput Rates

Signal strength is one of the factors that determine the theoretical throughput of a wireless

LAN. Wireless LAN components lower their data rate automatically when the received signal

power is no longer sufﬁcient for a higher throughput. Furthermore, the received signal must

also be greater than the noise due to interference, typically by 10 dB. Thus the signal quality

is characterized in terms of the signal-to-noise ratio (SNR).