1. IFIP-UNU ADVANCED COURSE ON NETWORKING AND SECURITY Module II-Wireless Communications Section 7
Antennas

2. Overview
This module will cover basic antenna theory, including directional and omni directional antenna selection. After discussing antenna theory and types of antennas, cables, connectors and accessories for antennas will be discussed. Additionally, important antenna design considerations, such as link engineering, path planning, and installation are also discussed.

3. 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.

4. Key terms Lobes Directional Omnidirectional Beamwidth and Bandwidth
Polarization
Vertical
Horizontal
Diversity
Plane (H and E)
Fresnel Zone

5. Definition of Terms dB- Decibel- Ratio of one value to another
dBx where x =
m = compared to 1 milliwatt (0 dBm=1 mW)
i = compare to isotropic antenna
d = compared to dipole antenna
w = compared to 1 watt (0 dBw = 1 watt)

6. Antennas

7. Important Antenna Concepts

8. Beamwidth

9. 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 b supplied cables, RF devices and antennas have reverse polarity TNC (RP-TNC) connectors
Cisco Aironet supplied antennas meet all FCC rules
Wide variety of b antennas for most applications

10. 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 a radios utilize both UNII-1 and UNII-2 bands, therefore cannot have external or removable antennas
Cisco a antennas are integrated into the radio module
Cisco 1400 radios utilize UNII-3 bands, therefore have external or removable antennas

11. Antenna Concepts Directionality Gain Polarization
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

12. 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

13. 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

14. Beamwidth vs. Gain

15. Antenna Theory
A theoretical isotropic antenna has a perfect 360º vertical and horizontal beamwidth
This is a reference for ALL antennas

16. Antenna Theory- Dipole
Energy lobes are ‘pushed in’ from the top and bottom
Higher gain
Smaller vertical beamwidth
Larger horizontal lobe
Typical dipole pattern
Side View
(Vertical Pattern)
Top View
(Horizontal Pattern)
New Pattern (with Gain)
Vertical Beamwidth

17. High Gain Omni-Directionals
More coverage area in a circular pattern
Energy level directly above or below the antenna will become lower

18. Directional Antennas
Lobes are pushed in a certain direction, causing the energy to be condensed in a particular area
Very little energy is in the back side of a directional antenna
Side View
(Vertical Pattern)
Top View
(Horizontal Pattern)

19. 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

20. 2.4 GHz EIRP Rules for FCC Governed Areas
Point-to-Multipoint
FCC allows increasing the gain of an antenna/cable system if the transmitter power is reduced below 30 dBm in a 1:1 ratio
Reduce Transmit Power below maximum of 30 dBm by 1 dBm and increase antenna/cable system gain by 1dBi
Point-to-Point
Maximum of 36 dBm EIRP
Installations – 30 dBm maximum transmitter power with 6 dBi in gain attributed to antenna and cable combination
FCC allows exceeding the 36 dBm EIRP in Point-to-Point installations using the 3:1 rule
Reduce Transmit Power below maximum of 30 dBm by 1 dBm and increase antenna/cable system gain by 3 dBi

21. 2.4 GHz EIRP Rules for FCC Governed Areas (cont.)
Point-to-Multipoint
Transmitter Power
Transmitter dBm
Maximum Gain
EIRP
FCC Maximum
1 Watt
30 dBm
6 dBi
36 dBm
Cisco Maximum
100 mW
20 dBm
16 dBi
36 dBm
The above values reflect the 1:1 rule
Point-to-Point
Transmitter Power
Transmitter dBm
Maximum Gain
EIRP
FCC Maximum
1 Watt
30 dBm
6 dBi
36 dBm
Cisco Maximum
100 mW
20 dBm
36 dBi
56 dBm
The above values reflect the 3:1 rule

22. 2.4 GHz EIRP Rules for ETSI Governed Countries
Currently ETSI stipulates a maximum of 20 dBm EIRP on Point-to-Multipoint and Point-to-Point installations –17 dBm maximum transmitter power with 3 dBi in gain attributed to antenna and cable combination
Professional installers are allowed to increase the gain of an antenna/cable system if the transmitter power is reduced below 17 dBm in a 1:1 ratio
Reduce Transmit Power below maximum of 17 dBm by 1 dBm and increase antenna/cable system gain by 1 dBi

23. 2.4 GHz EIRP Rules for non-FCC Governed Bodies
Governing bodies with 20 dBm ceiling on EIRP: ETSI, France/Singapore, Israel, Mexico
Point-to-Multipoint and Point-to-Point
Transmitter Power
Transmitter dBm
Maximum Gain
EIRP
Gov. Body Maximum
50 mW
17 dBm
3 dBi
20 dBm
Cisco Integrated Antennas
50 mW
17 dBm
2.2 dBi
19.2 dBm
Reduced TX Power
30 mW
15 dBm
5 dBi
20 dBm
Reduced TX Power
20 mW
13 dBm
7 dBi
20 dBm
Reduced TX Power
5 mW
7 dBm
13 dBi
20 dBm
Reduced TX Power
1 mW
0 dBm
20 dBi
20 dBm
The above values reflect the 1:1 rule

24. 802.11a and FCC 5 GHz Specifications
FCC regulations for UNII-1 and UNII-2
UNII-1
FCC max 50 mW
802.11a max 40 mW
With max 6 dBi antenna gain
802.11a max of 40 mW complies with all countries except Singapore (20 mW)
UNII-2
FCC max 250 mW
802.11a max 200 mW

25. FCC Rules for 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
FCC requires radios operating in both UNII-1 and UNII-2 bands must comply with antenna rules regulating UNII-1 band (including indoor use only)
The Cisco Aironet a radios utilize both UNII-1 and UNII-2 bands, therefore cannot have external or removable antennas and must be used indoors only
Cisco a antennas are integrated into the radio module

26. Omni directional Antennas

27. 2.4 GHz Omni-Directional Antennas
2 dBi Dipole "Standard Rubber Duck"

28. 2.4 GHz Omni-Directional Antennas
5.2 dBi Mast Mount Vertical

29. 2.4 GHz Omni-Directional Antennas
5.2 dBi Ceiling Mount

30. 2.4 GHz Omni-Directional Antennas
5.2 dBi Pillar Mount Diversity

31. 2.4 GHz Diversity Omni-Directional Antennas
2 dBi Diversity Omni-Directional Ceiling Mount

32. 2.4 GHz Omni-Directional Antennas
12 dBi Omni-Directional (Outdoor only)

33. 5 GHz Omni-Directional Antennas
9 dBi omni (Vertical polarization)

34. 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 6 dBi patch position
In 5 dBi omni position

35. Cisco Aironet 1100 Series Internal View
2.2 dBi Omni-Directional Diversity Antennas
Mini-PCI Radio
Option 1: b

36. Cone of reduced coverage Cone of reduced coverage
Cisco Aironet 1100 Series Antenna Details
Cone of reduced coverage
Sphere of influence
Sphere of influence
Cone of reduced coverage

37. Cisco Aironet 1100 Series Antenna Details (cont.)
H-Plane Pattern
E-Plane Pattern
Floor
Top View
Side View

38. Directional Antennas

39. 2.4 GHz Diversity Antennas
6.5 dBi Diversity Patch Wall Mount – 55 degree

40. 2.4 GHz Directional Antennas (cont.)
6 dBi Patch Antenna – 65 degree

41. 2.4 GHz Directional Antennas (cont.)
8.5 dBi Patch Antenna – 60 degree

42. 2.4 GHz Directional Antennas (cont.)
13.5 dBi Yagi Antenna – 25 degree

43. 13.5 dBi Yagi Antenna—Inside view

44. 2.4 GHz Directional Antennas (cont.)
21 dBi Parabolic Dish Antenna – 12 degree

45. 5 GHz Omni-Directional Antennas
28 dBi dish (H or V polarization)

46. 5 GHz Antenna
9.5 dBi sector (H or V polarization)

47. Cable and Accessories

48. 2.4 GHz Accessories

49. RP-TNC Connectors

50. 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
Lug
Lockwasher
Nut
Ground Wire
From RF Device

51. Lightning Arrestor

52. 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

53. 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 a technology

54. 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

55. Link Engineering and RF Path Planning

56. Path Considerations Radio line of sight Earth bulge Fresnel zone
Antenna and cabling
Data rate

57. 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!

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

59. Fresnel Zone

60. Improving Fresnel Effect
Raise the antenna
New structure
Existing structure
Different mounting point
Remove trees

61. Site to Site Fresnel Zone
Antenna Height
Fresnel zone consideration
Line-of-Sight over 25 miles (40 Km) hard to implement
Antenna Height (Value “H”)
Total Distance
60% (Value “F”)
Earth Curvature (Value “C”)

62. Antenna Alignment
Line of Sight

63. High gain omni-directional
Antenna Issues
High gain omni-directional
Directional antenna
No Downtilt
One-way communications

64. Antenna Issues (cont.) 8.50 downtilt 200 ft./61 m 14.50 700 ft./213 m
8 Miles/13 Km

65. Antenna Issues (cont.) Omni-directional antennas provide 3600 coverage
Also accepts interference from all directions

66. Antenna Installation

67. Antenna Mounting

68. Mounting (Cont.)

69. Interference Carrier Detect Test (Spectrum Analyzer) Built into Bridge
Run from Console Menu

70. Antenna Installation
Towers and antennas may require permits and must meet local regulations

71. Antenna Installation (cont.)
Antenna Alignment Tool
Id Name Address Signal Strength Signal Quality
18 Cisco Bridge # fd % -10 dBm %
17 Cisco Bridge # fd % -10 dBm %
16 Cisco Bridge # fd % -73 dBm %
15 Cisco Bridge # fd % -77 dBm %
14 Cisco Bridge # fd % -10 dBm %
13 Cisco Bridge # fd % -67 dBm %
12 Cisco Bridge # fd % -77 dBm %
11 Cisco Bridge # fd % -64 dBm %
10 Cisco Bridge # fd % -10 dBm %
9 Cisco Bridge # fd % -73 dBm %

72. Antenna Installation (cont.)
Aironet Client Utility
Site Survey Utility for antenna alignment

73. Labs

74. Labs of Section 7 Lab 7.1.4 Antenna Setup
Lab Configure AP Diversity Settings
Lab Configure Bridge Diversity Settings
Lab Omnidirectional Antennas
Lab Directional Antennas