Aerohive BR200-WP, Hardware Reference Manual

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Chapter A
116 Aerohive
Figure 6 Directional antenna patterns
Omnidirectional Antennas
You typically orient omnidirectional antennas vertically, positioning them on all devices in the same
direction. Omnidirectional antennas create coverage areas that can be toroidal (doughnut-shaped) or
cardioid (heart- or plum-shaped), broadcasting to the sides much more effectively than up or down (see
Figure 7 ). In general, this is good for most office environments because you have large flat floors. However, it
can be a problem in environments with high ceilings.
Figure 7 Omnidirectional antenna radiation patterns
MIMO
MIMO (Multiple In, Multiple Out) is a major WLAN advancement introduced in the IEEE 802.11n standard in
which multiple RF links are formed on the same channel between the transmitter and receiver
simultaneously. To accomplish this, the transmitter separates a single data stream into multiple spatial
streams, one for each RF chain (an a various digital signal processing modules linked to the
antenna). The transmit antennas at the end of each RF chain then transmit their spatial streams. The
Higher gain
Lower gain
(Bird’s eye view)
Patch
antennas
Higher gain
Toroidal pattern Cardioid pattern