© 2003, Cisco Systems, Inc. All rights reserved. FWL 1.0—7-1 Learning Objectives Define how an antenna is used to propagate an RF signal. Define basic

© 2003, Cisco Systems, Inc. All rights reserved. FWL 1.0—7-1

Learning Objectives

•Define how an antenna is used to propagate an RF signal.

•Define basic facts of EIRP.

•Define facts on FCC regulations for UNII-1, UNII-2 and UNII-3.

•Identify what an isotropic antenna is and why it is used as a reference for other antennas.

•Identify Cisco Aironet antennas, their coverage patterns, and the proper polarization of each antenna.


Beamwidth


Cisco Aironet 802.11b Antennas

FCC requires that ALL antennas sold by a spread spectrum vendor be certified with the radio they are to be sold with

All Cisco Aironet 802.11b supplied cables, RF devices and antennas have reverse polarity TNC (RP-TNC) connectors

Cisco Aironet supplied antennas meet all FCC rules

Wide variety of 802.11b antennas for most applications


Cisco Aironet 802.11a Antennas

FCC requires that all radios utilizing the UNII-1 Band (5.15 GHz – 5.25 GHz) must have non-removable or integrated antennas

FCC allows radios utilizing the UNII-2 Band (5.25 GHz – 5.35 GHz) to have external or removable antennas

The Cisco Aironet 802.11a radios utilize both UNII-1 and UNII-2 bands, therefore cannot have external or removable antennas

Cisco 802.11a antennas are integrated into the radio module

Cisco 1400 radios utilize UNII-3 bands, therefore have external or removable antennas


Antenna Concepts

Directionality• Omni (360º coverage) directional

• Directional (limited range of coverage)

Gain• Measured in dBi and dBd (0 dBd = 2.14 dBi)

• More gain means more coverage - in certain directions

Polarization• Antennas are used in the vertical polarization


Antenna Issues (cont.)

Antennas have gain in particular directions

Direction other than the main intended radiation pattern, are typically related to the main lobe gain


Antenna Gain

If the gain of an antenna goes up, the coverage area or angle goes down

Coverage areas or radiation patterns are measured in degrees

Angles are referred to as beamwidth• Horizontal measurement

• Vertical measurement


Beamwidth vs. Gain


Antenna Theory

A theoretical isotropic antenna has a perfect 360º vertical and horizontal beamwidth

This is a reference for ALL antennas


FCC Part 15 Antenna Requirements

802.11b antenna• Must use a unique, or proprietary connector

• Cisco Aironet products use RP-TNC connector

Part 15 standards• Approved antenna may exceed

• Exceeding may lead to interference problems

• Penalties could result in fines

• FCC standards apply to Part 15 users in the United States

Different countries will have similar standards


2.4 GHz EIRP Rules for FCC Governed Areas (cont.)

Transmitter Power

Transmitter Power

EIRPEIRP

Cisco MaximumCisco Maximum

6 dBi6 dBi 36 dBm36 dBm

100 mW100 mW 20 dBm20 dBm

FCC MaximumFCC Maximum

Maximum Gain

Maximum Gain

Transmitter dBm

Transmitter dBm

1 Watt1 Watt

Point-to-MultipointPoint-to-Multipoint

30 dBm30 dBm


Transmitter Power

Transmitter Power

EIRPEIRP

Cisco MaximumCisco Maximum


100 mW100 mW 20 dBm20 dBm

FCC MaximumFCC Maximum

Maximum Gain

Maximum Gain

Transmitter dBm

Transmitter dBm

1 Watt1 Watt

Point-to-PointPoint-to-Point

30 dBm30 dBm


The above values reflect the 1:1 rule

The above values reflect the 3:1 rule


2.4 GHz Omni-Directional Antennas

2 dBi Dipole "Standard Rubber Duck"



5.2 dBi Mast Mount Vertical



5.2 dBi Ceiling Mount



5.2 dBi Pillar Mount Diversity


2.4 GHz Diversity Omni-Directional Antennas

2 dBi Diversity Omni-Directional Ceiling Mount



12 dBi Omni-Directional (Outdoor only)


5 GHz Omni-Directional Antennas

9 dBi omni (Vertical polarization)


5 GHz Integrated Antenna

Innovative 5 GHz Combo Antenna:• Wall Mount: Fold antenna flat

against access point housing for 6 dBi gain patch antenna

• Ceiling Mount: Fold antenna out at a 90° angle for 5 dBi gain omni antenna

In 5 dBi omni position

In 6 dBi patch position


Mini-PCI RadioMini-PCI Radio

2.2 dBi Omni-Directional Diversity Antennas2.2 dBi Omni-Directional Diversity Antennas

•Option 1: 802.11b•Option 1: 802.11b

Cisco Aironet 1100 Series Internal View


Cisco Aironet 1100 Series Antenna Details

Cone of reduced coverage


Sphere of influenceSphere of influence

Sphere of influenceSphere of influence




H-Plane Pattern E-Plane Pattern

Top View Side View

Floor

H-Plane Pattern, Ivory Antenna = 90 degs Plane Cut (in x-y plane)

-20

-15

-10

-5

0

5

H-Plane Pattern, Ivory Antenna = 90 degs Plane Cut (in x-y plane)

-20

-15

-10

-5

0

5

E-Plane Pattern, Ivory Antenna = 0 degs Plane Cut (cut along x-z axis)

-25

-20

-15

-10

-5

0

5

E-Plane Pattern, Ivory Antenna = 0 degs Plane Cut (cut along x-z axis)

-25

-20

-15

-10

-5

0

5

Cisco Aironet 1100 Series Antenna Details (cont.)


Directional Antennas


2.4 GHz Diversity Antennas

6.5 dBi Diversity Patch Wall Mount – 55 degree


2.4 GHz Directional Antennas (cont.)

6 dBi Patch Antenna – 65 degree



8.5 dBi Patch Antenna – 60 degree



13.5 dBi Yagi Antenna – 25 degree


13.5 dBi Yagi Antenna—Inside view



21 dBi Parabolic Dish Antenna – 12 degree


5 GHz Omni-Directional Antennas

• 28 dBi dish (H or V polarization)


5 GHz Antenna

• 9.5 dBi sector (H or V polarization)


Cable and Accessories


2.4 GHz Accessories


RP-TNC Connectors


Lightning Arrestor

Designed to protect LAN devices from static electricity and lightning surges that travel on coax transmission lines

RP-TNC connectors used on all Cisco Antennas

To Antenna

Ground Wire

From RF Device

Lug

LockwasherNut


Lightning Arrestor


Coax Connection Sealing

Number one problems with bridges - water in the connectors

Proper sealing is important

Coax Seal is one product that is inexpensive and works great


1400 Accessories

Antenna Alignment Assistance with status/alignment LEDs and RSSI port on outdoor unit

Quick-hang mounting bracket supports weight of radio during installation process

Complete solution provided with radio including:

•Power Injector LR

•Multi Function Mount

•20’ and 50’ length of dual RG-6 cable

•Power supply and cord

•Coaxial sealant for all exposed connectors

•Corrosion proof gel for exposed metal surfaces

Management via SNMP, Telnet CLI, HTTP

Based upon 802.11a technology


1400 Power Injector LR

Converts standard 10/100 baseT Ethernet RJ-45 interface to F-Type connector dual coaxial cable

Power provided over dual coaxial cable with power discovery to protect other appliances

Support for longer cable runs by resetting the 100 meter, 100baseT Ethernet timer, enabling total cable runs of 200 meters.

Surge protection provided at the F-Type connectors to protect infrastructure devices


Link Engineering and RF Path Planning


Path Considerations

Radio line of sight

Earth bulge

Fresnel zone

Antenna and cabling

Data rate


Line of Sight

The following obstructions might obscure a visual link:• Topographic features, such as mountains

• Curvature of the Earth

• Buildings and other man-made objects

• Trees

Line of sight!


Longer Distances

Line of Sight disappears at 6 miles (9.7 Km) due to the earth curve


Fresnel Zone


Improving Fresnel Effect

Raise the antenna

New structure

Existing structure

Different mounting point

Remove trees


Total Distance

Fresnel @ 60% (Value “F”)

Earth Curvature (Value “C”)

Antenna Height (Value “H”)

Site to Site Fresnel Zone

Antenna Height• Fresnel zone consideration

• Line-of-Sight over 25 miles (40 Km) hard to implement


Antenna Alignment

Line of Sight


Antenna Issues

•No Downtilt

•One-way communications

High gain omni-directional

Directional antenna



8 Miles/13 Km

700 ft./213 m

8.50 downtilt

14.50

200

ft.

/61

m



Omni-directional antennas provide 3600 coverage

Also accepts interference from all directions


Antenna Installation


Antenna Mounting


Mounting (Cont.)


Interference

Carrier Detect Test (Spectrum Analyzer)• Built into Bridge

• Run from Console Menu


Antenna Installation

Towers and antennas may require permits and must meet local regulations


Antenna Installation (cont.)

Antenna Alignment Tool Id Name Address Signal Strength Signal Quality

18 Cisco Bridge #1 00409644fd35 100% -10 dBm 100%











Antenna Installation (cont.)

Aironet Client Utility

Site Survey Utility for antenna alignment


Ladder Safety


Summary

• Identify characteristics of Cisco Aironet 802.11a antennas.

• Identify characteristics of Cisco Aironet 802.11b antennas.

606060© 2003, Cisco Systems, Inc. All rights reserved.

Documents

© 2003, Cisco Systems, Inc. All rights reserved. FWL 1.0—7-1 Learning Objectives Define how an antenna is used to propagate an RF signal. Define basic