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© 2008 Cisco Systems, Inc. All rights reserved. IUWNE v1.0—1-1

Wireless Fundamentals

Describing Antennae


Antenna Principles The radiation

pattern describes coverage shape.

RF radiation pattern is described by E-plane (elevation chart) and H-plane (azimuth chart).

Expressed in dB. Each antenna

design produces different RF radiation patterns.


Polarization Polarization describes the

orientation of the electric field. It can be linear or circular. The magnetic field is on the right

of the electric field. Wireless antennae can use any

polarization, but consistency is required. Vertical polarization is common.

Editor

In the sentences under the first two illustrations, lowercase the "L" in "Loop" and add periods. In the last label capitalize the "p" in "Polarization"


Magnetic Field 90 degrees perpendicular to the electric field


Diversity

Some wireless technologies use diversity to choose, on a per-client basis, which antenna to use to receive and which to answer. Antennae should be the same type and in the same area.

Editor

Please use initial caps for "Good Reception" and "Poor Reception"


Antenna Types


Basic Omnidirectional

“Rubber Duck” 2.14 dBi Dipole

Editor

In the middle of the circles, please hyphenate "H-plane" and "E-plane"

Robin Tardo

Robin Tardo6/20/2008And initial-cap "Plane" in the labels


Omnidirectionals

AIR ANT 1728, Ceiling MountOmni 5.2 dBi

Editor


Robin Tardo

And initial-cap "Plane" in both, in this slide and the next similar ones


AIR ANT 2506/24120

5.2 dBi Omni Mast Mount12 dBi Omni Mast Mount

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Special “Omnis”

Dual Patch Omnidirectional5.2 dBi, Pillar Mount


Directional Antennae

8.5 dBi Patch, Wall Mount

Editor



Directional13.5 dBi Yagi Ude Butterfly Effect, Polarization

Editor



Directional (Cont.)

21 dBi Parabolic Dish

Editor



Cables and Connectors

“RP-TNC” connectoris used on

most Cisco APs.

“N” connectoris used on the

1500 Mesh and 1400

Bridge.

“RP-SMA” connector isused on some Linksys products.

“SMA” connector is used on“pig-tail” type cable assemblies.


An attenuator would be positioned in the same way as the amplifier, but it would not require a power supply.

Attenuators and Amplifiers


Lightening Arrestors

Model to Insert Between Antenna and Cable


Lightening Arrestors (Cont.)

Fiber Interface

Ethernet Lightening Arrestor


Splitters

Splitters divide the signal between two antennae, but considerably reduce range: a 21 dBi dish loses 4 dBi. Its range drops from 33 to 21 km on each side.


Summary

Each antenna radiates in a unique way. Wireless uses vertical polarization. Some APs use diversity to offer better resistance to multipath issues. Antennae can be directional or omnidirectional. Omnidirectional antennae radiate 360 degrees in the H-plane. Directional antennae focus their beam more or less depending on

models. Connectors are usually specific to a vendor. Attenuators and amplifiers can be added to change the power transmitted

to the antenna. Lightening arrestors can mitigate the impact of surrounding lightening

strikes on the AP and the network. Splitters can be used to split the signal of one AP to two antennae.


Technology

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