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Antennas for CDMA System

Antennas for CDMA System. Contents. Base station antenna specification and meanings Antenna types and trends. Technical Data. Electrical properties Operation Frequency Band Input impedance VSWR Polarization Gain Radiation Pattern Horizontal/Vertical beamwidth Downtilt

lydia-richardson
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Antennas for CDMA System

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  1. Antennas for CDMA System

  2. Contents Base station antenna specification and meanings Antenna types and trends

  3. Technical Data

  4. Electrical properties Operation Frequency Band Input impedance VSWR Polarization Gain Radiation Pattern Horizontal/Vertical beamwidth Downtilt Front/back ratio Sidelobe suppression and null filling Power capability 3rd order Intermodulation Insulation Mechanical properties Size Weight Robe material Appearance and color Working temperature Storage termperature Windload Connector types Package Size Lightening

  5. Electrical properties

  6. Wavelength 1/4 Wavelength 1/2 Wavelength 1/4 Wavelength 1/2 Wavelength Dipole 1900MHz ：157mm 800MHz ：375mm Dipoles

  7. 1个 dipole(received power)：1mW Multiple dipole matrix Received power：4 mW GAIN= 10log(4mW/1mW) = 6dBd

  8. Antenna (Overlook Omnidirectional array”Received power：1mW “Sector antenna”Received power：8mW Gain=10log(8mW/1mW) = 9dBi

  9. Frequency Range • CDMA(CELLULA） 800 MHz: 824-894MHz • CDMA(PCS/PCN) 1900 MHz: 1850-1990MHz

  10. Impedance • 50 Antenna 50 ohms Cable 50 ohms

  11. 80 ohms 50 ohms VSWR Forwarda: 10W 9.5 W Backward: 0.5W Return Loss： 10log(10/0.5) = 13dB VSWR (Voltage Standing Wave Ratio)

  12. 1.5 • =(VSWR-1)/(VSWR+1) • RL=-20lg 

  13. Polarization Vertical Horizontal - 45degree slant + 45degree slant

  14. V/H (Vertical/Horizontal) Slant (+/- 45°)

  15. Linear,vertical • dual linear 45 slant

  16. 2.15dB dBd and dBi Ideal radiating dot source (lossless radiator) eg: 0dBd = 2.15dBi Dipole

  17. Pattern

  18. 3dB Beamwidth 10dB Beamwidth Peak - 3dB Peak - 10dB 120° (eg) 60° (eg) Peak Peak Peak - 3dB Peak - 10dB Beamwidth

  19. 3dB Beam width Horizontal • Directional Antenna：65°/90°/105°/120 °Omni：360°

  20. 3dB Beam width Vertical Directional： Omni-directional：

  21. Down Tilt • Mechanical down tilt • Fixed electronic down tilt • Adjustable electronic down tilt

  22. Demonstration of Electronic Down-tilt

  23. Mechanical downtilt Non down tilt Electronic downtilt

  24. Front to Back Ratio • Ratio of maximum mainlobe to maximum sidelobe Back power Front power F/B = 10 log(FP/BP) typically ： 25dB

  25. Upper Side lobes Suppression & Null Fill

  26. UP SIDELOBE (dB) DOWN SIDELOBE(dB) Sidelobes

  27. Permitted Power • Continuous :25-1500watts • peak :n2p

  28. Isolation 10log(1000mW/1mW) = 30dB 1000mW ( 1W) 1mW

  29. Mechanical properties

  30. Dimensions • LWH • Length：connected with vertical bandwidth and gain • Width：connected with horizontal bandwidth • Height：connected with techniques adopted

  31. Weight • Affecting transmission and deploy

  32. RadomeMaterial • PVC, Fiberglass • Anti-temperature、water-proof，anti-aging，weather resistant

  33. Colour • Good-looking, environment-protecting

  34. Operating Temperature Range • Typical range：-40°C — +70°C

  35. Storage Temperature Range • Typically：-40°C — +70°C

  36. Wind Load • Eg: 83N at 160 km/h

  37. Connector Type • 7/16”DIN，N，SMA • female

  38. Mast • Mast diameter 45-90mm

  39. Lightening Protection • Direct Ground

  40. Antenna Directional Coupler TX D u p l e x e r Comb -iner Jumper Transmission Line TX F R Jumpers RX BPF Antenna Systems • Antenna systems include more than just antennas • Transmission Lines • necessary to connect transmitting and receiving equipment • Other Components necessary to achieve desired system function • Filters, Combiners, Duplexers - to achieve desired connections • Directional Couplers, wattmeters - for measurement of performance • Manufacturer抯 system may include some or all of these items • remaining items are added individually as needed by system operator

  41. Typical Coaxial Cables Used as Feeders in Wireless Applications Foam Dielectric Air Dielectric Characteristics of Transmission Lines Physical Characteristics • Type of Line • coaxial, stripline, open-wire • balanced, unbalanced • Physical Configuration • Dielectric: • air • foam • Outside Surface: • unjacketed • jacketed • special: plenum rated • Size (nominal outer diameter) • 1/4?1/2? 7/8? 1-1/4? 1-7/8? 2-1/4? 3

  42. D d Characteristic Impedance of a Coaxial Line Zo = ( 138 / ( 1/2 ) ) Log10 ( D / d )  = Dielectric Constant = 1 for vacuum or dry air Characteristics of Transmission Lines Electrical Characteristics • Attenuation: • varies with frequency, size, dielectric characteristics of insulation • usually specified in db/100 ft and/or db/100 m • CharacteristicImpedance ZO (50 ohms is the usual commercial standard; 75 sometimes used) • value set by inner/outer diameter ratio and dielectric characteristics of insulation • connectors must preserve constant impedance (see figure at right) • VelocityFactor • determined by dielectric characteristics of insulation. • Power-HandlingCapability • varies with size, conductor materials, dielectric characteristics

  43. Matched Condition ZIN = 50 Zo=50 ZLOAD= 50 Mis-Matched Condition ZLOAD= 83 -j22 ZIN = ? Zo=50 Deliberate Mis-Match for Impedance Transformation /4 ZLOAD= 100 ZIN=25 Zo=50 ZIN= ZO2/ ZLOAD Transmission Lines:Special Electrical Properties • Transmission lines have impedance-transforming properties • When terminated with same impedance as Zo, input to line appears as impedance Zo • When terminated with impedance different from Zo, input to line is a complex function of frequency and line length. Use Smith Chart or formulae to compute • Special case of interest: Line section one-quarter wavelength long has convenient properties useful in matching networks • ZIN = (Zo2)/(ZLOAD)

  44. Air Dielectric Foam Dielectric Transmission Lines:Some Practical Considerations • Transmission Lines: Some Practical Considerations • Periodicity of inner conductor supporting structure can cause VSWR peaks at some frequencies, so specify the frequency band when ordering • Air dielectric lines: • lower loss than foam-dielectric; dry air is excellent insulator • shipped pressurized; do not accept delivery if pressure leak • Foam dielectric lines • simple, low maintenance; despite slightly higher loss • small pinholes and leaks can allow water penetration and gradual attenuation increases

  45. MAIN FEEDER

  46. JUMP CABLE

  47. 7DIN CONNECTOR DIN & N CONNECTOR

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