rf propogation
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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
CS698tWireless Networking:Principles and Practice
Lecture 0202 Aug 2005, Tuesday
Bhaskaran Raman
Department of CSEIndian Institute of Technology, Kanpur
http://www.cse.iitk.ac.in/users/braman/courses/wless-fall2005/
Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
From Previous Lecture...
Cellular operational frequencies in India
Scribe for today?
Terms: spectrum, bandwidth
Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Three Basic Propagation
Phenomena
Reflection Diffraction Scattering
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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Electro-Magnetic Spectrum
103 102 101 100 10-1 10-2 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 10-11 10-12
106 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
Common
nameLF MF HF VHF UHF SHF EHF
ISM band: 902-928MHz, 2400-2483.5MHz, 5725-5850MHz
Wavelength (m)
Frequency (Hz)
IR UV X-Rays
Radio
TVCellular Propagation depends on:
Distance, environment, frequency
Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
dB: Relative Measure(to measure propagtion)
Gravitational
force on a mass
m at distance d
Gravitational
force on a mass
m at distance d/2
4 timer more
Gravitational
force on a mass
m at distance 10d
100 times less
6dB more 20dB less
Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Measuring Path Loss in dB
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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Measuring Absolute Power indBm
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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Putting Together dB and dBm
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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Antenna Gain
Antenna Gain G: ratio of transmit/receive power in a
particular direction, to that of an isotropic antenna
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Transmit gain == Receive gain
Typically, gain is expressed in dBi
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Bhaskaran Raman, Department of CSE, IIT Kanpur Wireless Networks: Principles and Practice, Fall 2005
Antenna Radiation Pattern
0o
90o
180o
270o
0dB
-3dB
-10dB
-20dB
-30dB
Side-lobe
rejection
levels
Main direction
Side-lobes
Parabolic Grid
Antenna
Other antennas/patterns: http://www.hyperlinktech.com/