1. Olga Torstensson Halmstad University
Antennas
Olga Torstensson
Halmstad University

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

3. 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)

4. Important Antenna Concepts

5. Beamwidth

6. 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

7. 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

8. 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

9. Beamwidth vs. Gain

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

11. 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

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

13. 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)

14. 2.4 GHz Omni-Directional Antennas
2 dBi Dipole "Standard Rubber Duck"

15. 2.4 GHz Omni-Directional Antennas
5.2 dBi Mast Mount Vertical

16. 2.4 GHz Omni-Directional Antennas
5.2 dBi Ceiling Mount

17. 2.4 GHz Omni-Directional Antennas
5.2 dBi Pillar Mount Diversity

18. 2.4 GHz Diversity Omni-Directional Antennas
2 dBi Diversity Omni-Directional Ceiling Mount

19. 2.4 GHz Omni-Directional Antennas
12 dBi Omni-Directional (Outdoor only)

20. 5 GHz Omni-Directional Antennas
9 dBi omni (Vertical polarization)

21. 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

22. 2.4 GHz Diversity Antennas
6.5 dBi Diversity Patch Wall Mount – 55 degree

23. 2.4 GHz Directional Antennas (cont.)
6 dBi Patch Antenna – 65 degree

24. 2.4 GHz Directional Antennas (cont.)
8.5 dBi Patch Antenna – 60 degree

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

26. 13.5 dBi Yagi Antenna—Inside view

27. 2.4 GHz Directional Antennas (cont.)
21 dBi Parabolic Dish Antenna – 12 degree

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

29. 5 GHz Antenna
9.5 dBi sector (H or V polarization)

30. Cable and Accessories 2.4 GHz Accessories

31. RP-TNC Connectors

32. 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

33. Lightning Arrestor

34. 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
ces

35. Link Engineering and RF Path Planning
Path Considerations Radio line of sight
Earth bulge
Fresnel zone
Antenna and cabling
Data rate

36. 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!

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

38. Fresnel Zone

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

40. 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”)

41. Antenna Alignment
Line of Sight

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

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

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

45. Antenna Mounting

46. Mounting (Cont.)

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