01- RF and Wireless Fundamentals - 12 Jun 2011

8/12/2019 01- RF and Wireless Fundamentals - 12 Jun 2011

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Some Important Wireless TerminologyModule # 236Saturday, June 11, 2011

Some Wireless TerminologySaturday, June 11, 2011

Some Wireless Terminology Line-of-Sight (LOS)

Saturday, June 11, 2011

Some Wireless Terminology Line-of-Sight (LOS) Non-Line-of-Sight


Some Wireless Terminology Line-of-Sight (LOS) Non-Line-of-Sight Fading Flat Fading Frequency Selective Fading Narrowband Frequency Fade

Saturday, June 11, 2011Some Wireless Terminology

Line-of-Sight (LOS) Non-Line-of-Sight Fading Flat Fading Frequency Selective Fading Narrowband Frequency Fade Multipath Interference


Line-of-Sight (LOS)


Line-of-Sight (LOS) Visual LOS must be achieved


Line-of-Sight (LOS) Visual LOS must be achieved Must be observed from the antenna


Line-of-Sight (LOS) Visual LOS must be achieved

Must be observed from the antenna Fresnel Zone must be consideredSaturday, June 11, 2011

Non-Line-of-Sight (NLOS)Saturday, June 11, 2011

Non-Line-of-Sight (NLOS) Transmitter & receiver antennas having reflectors &/

or absorbers between them


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or absorbers between them Results in degradation of the received signal power

or fadingSaturday, June 11, 2011


or absorbers between them Results in degradation of the received signal power

or fading Types of fading: Flat Fading Frequency Selective Fading


Flat FadingSaturday, June 11, 2011

Flat Fading Caused by absorbers between 2 antennas

Saturday, June 11, 2011Flat Fading

Caused by absorbers between 2 antennas Frequency dependent


Flat Fading Caused by absorbers between 2 antennas Frequency dependent Countered by antenna placement & transmit power

levelSaturday, June 11, 2011

Flat Fading Caused by absorbers between 2 antennas Frequency dependent Countered by antenna placement & transmit power

levelSaturday, June 11, 2011

Frequency Selective FadingSaturday, June 11, 2011

Frequency Selective Fading Caused by reflectors between transmitter & receiver


Frequency Selective Fading Caused by reflectors between transmitter & receiver Results in multipath


Frequency Selective Fading Caused by reflectors between transmitter & receiver Results in multipath


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More Frequency Selective FadingSaturday, June 11, 2011

More Frequency Selective Fading Spectral response dips or fades


More Frequency Selective Fading Spectral response dips or fades Reflections can lead to multipath signals & deep

nullsSaturday, June 11, 2011

More Frequency Selective Fading Spectral response dips or fades Reflections can lead to multipath signals & deep

nullsSaturday, June 11, 2011

Narrowband in Frequency FadeSaturday, June 11, 2011

Narrowband in Frequency Fade Null in the frequency response at the transmissionfrequency can lose signalSaturday, June 11, 2011

Narrowband in Frequency Fade Null in the frequency response at the transmission

frequency can lose signalSaturday, June 11, 2011

Multipath InterferenceSaturday, June 11, 2011

Multipath Interference Multipath interference can causeinter-symbol interferenceSaturday, June 11, 2011

Multipath Interference Multipath interference can cause

inter-symbol interference Distortion of the received signal Signal arrives at receiver at different times


Multipath Interference

Multipath interference can causeinter-symbol interference Distortion of the received signal Signal arrives at receiver at different times Receiver cannot reliably distinguish between

individual signal elementsSaturday, June 11, 2011

Delay SpreadSaturday, June 11, 2011


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Delay Spread Delayed multipath signal overlapping with following

symbolsSaturday, June 11, 2011

Delay Spread Delayed multipath signal overlapping with following

symbolsSaturday, June 11, 2011

Antenna BasicsModule # 346Saturday, June 11, 2011

47Antennas & Cables

Antenna Basics Cables & Connectors Peripheral Equipment


48

Antenna Basics Antenna function Radiation patterns Types of antennas Antenna parameters Implementation considerations Selecting antennas


49Antenna Function

Focus & absorb radio energy in specific directions,depending on design (radiation patterns)

Can be tuned to certain frequency rangesSaturday, June 11, 2011

50Radiation Patterns

The variation of the field intensity of an antenna as anangular function with respect to the axis

Usually represented graphically in either thehorizontal or vertical plane

May be interpreted as interference by anotherreceiving antennaSaturday, June 11, 2011

E-Plane Pattern H-Plane Pattern51Radiation Pattern ExamplesSaturday, June 11, 2011

52Types of Antennas

Currently there are five types of antennas availablefrom EION Wireless:

Omni s


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Yagi s Planar s Parabolic Grid s Parabolic Dish s Sectoral s


8 dBi Omni@ 915 MHz12 dBi Omni@ 2.4 GHz8 dBi Yagi@ 915 MHz53Omnis & YagisSaturday, June 11, 2011

21 dBi Dish@ 2.4 GHz16 dBi Planar@ 2.4 GHz18 dBi Grid@ 2.4 GHz54

Planars, Grids & DishesSaturday, June 11, 2011

TA2305H-2 Horizontal Sector TA2304-2 Vertical SectorTil-Tek Sectoral Antennas www.Til-Tek.com55SectoralsSaturday, June 11, 2011

56Antenna Parameters

Gain Beamwidth

Downtilt or Uptilt Front-to-Back Ratio Polarity & Cross-Polarization Discrimination Voltage Standing Wave Ratio


57Gain

Measure of their ability to focus signals in their tunedband

Achieved by focusing the signal A higher gain antenna has focused of compressed

the RF energy more in a given direction


58The Decibel

The unit that measures loudness or strength of asignal. dBs are a relative measurement derived froman initial reference level and a final observed level. Awhisper is about 20 dB, a normal conversation about60 dB, and loud thunder 110 dB. 120 dB is thethreshold of pain.


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dBm is referenced to 1 milli-watt. 30 dBm = 1 Watt (+ 3) dB = 2 times the power. i.e. 30 dBm = 1 watt, 33 dBm = 2 watts, 36 dBm = 4 watts (- 3) dB = times the power. i.e. 30 dBm = 1 watt, 27 dBm = .5 watts, 24 dBm = .25 watts


59dBd

Antenna Gain must be measured over a knownreference

Expressed in either dBd or dBi dBd Antenna Gain with respect to a half-wave dipole


60dBi

dBi Antenna Gain referenced over an isotropic radiator A theoretical antenna that radiates equally in all directions, e.g. the Sun EION Wireless uses dBi Conversion factor is: 0 dBd = 2.14 dBi A 10 dBd antenna will have a dbi gain of 12.14 dBi

Saturday, June 11, 201161Beamwidth

How a signal spreads out from an antenna The range of the reception area Measured between the points on the beam pattern

at which the power density is half of the maximumpower (often referred to as the -3 dB points)Saturday, June 11, 2011

-3 dBpoints

61Beamwidth How a signal spreads out from an antenna The range of the reception area Measured between the points on the beam pattern

at which the power density is half of the maximumpower (often referred to as the -3 dB points)Saturday, June 11, 2011

62More Beamwidth

High gain antenna has a very narrow beamwidth &may be more difficult to align


Focussed beamLess focussed beam62More Beamwidth

High gain antenna has a very narrow beamwidth &may be more difficult to alignSaturday, June 11, 2011


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E-PlaneH-Plane-3dB points63TIL-TEK TA-2304-45 SectorSaturday, June 11, 2011

64Downtilt or Uptilt

Further focuses the signal downward or upward withrespect to the horizon

Tilt may be: Electrically built into the antenna Achieved mechanically with mounting gear Necessary if there is a significant elevation deviation

between theRemote site(s) & Base siteSaturday, June 11, 2011

65Front-to-Back Ratio (F/B)

Directional antennas focus the signal in a forwardpath

Achieved by directing the signal in one direction

Reduces the signal in the opposite direction Higher gain antenna typically has a greater F/B ratioSaturday, June 11, 2011

Minimal signal here Signal is stronger here66Front-to-Back Ratio ExampleSaturday, June 11, 2011

67Polarity

Antennas have a polarity associated with them Antennas are usually vertically or horizontally

polarized The polarity of all antennas used in a segment mustbe the sameSaturday, June 11, 2011

68Cross-Polarization Discrimination

Cross-Polarization Discrimination (XPD) specifies theamount of signal isolation achieved when thereceiving element is perpendicular to the radiatingelement

May be advantageous whenco-locating radio systems


69Voltage Standing Wave Ratio

Voltage Standing Wave Ratio (VSWR) is the voltageratio of minimum to maximum across a transmissionline

2.0:1 or less is good in an antenna Most antennas are 1.5:1 Source of signal loss


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70Implementation Considerations

Absorption Diffraction Shadowing Multipath Interference


71Absorption

Antennas mounted too close to soft objects producea reduction in signal strength

If a system is installed in Winter, absorption may be aproblem when the trees grow their leaves backSaturday, June 11, 2011

72Absorption ExampleSaturday, June 11, 2011

72Absorption Example

Saturday, June 11, 201173Diffraction

When a radio signal reflects or bounces off a solidobject

The amount of diffraction could lead to connectivityproblems if the remaining signal level is too low

These are two types: Shadowing Multipath


74Shadowing When an antenna is mounted too close to a solid

surface Or the receive antenna is in a shadowed area Solution: Ensure adequate height above structures when mounting

antennaSaturday, June 11, 2011

Mounted too low and too farfrom the edgeMounted high enough & close

enough to the edge75Correcting ShadowingSaturday, June 11, 2011

76Multipath Interference

Same signal arrives at different times & confuses thereceiver

May be interpreted as interference by the receiver


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Can result in bit errors & processing delaysSaturday, June 11, 2011

77TIL-TEK TA-2304-45 Spec.Saturday, June 11, 2011

78Antenna Specification Sheets

Please visit www.til-tek.com and locate the TA-2408 antenna. It can be found underproducts by frequency band. It is a 2.4 GHz Planar antenna. Bookmark this specification sheet for uselater.

Frequency Band Gain Beamwidth Cross Polarization discrimination and Front to back ratios. Impedance Termination Type Wind rating and thrust Weight Radiation Patterns


79Cables & Connectors

Cables & connectors introduce some losses into thesystem

Greater loss with higher frequency Longer cable length means a greater dB loss Connectors introduce 1 dB of loss for the whole run


80Antenna Cable

EION Wireless recommends LMR 400

For Base station installations or long cable runs, usecable with very little loss LMR 600 & 7/8 Heliax cable types are also available

through EION Wireless Use LMR 400 Ultra-flex cable only for very short

lengthsSaturday, June 11, 2011

Cable Type 915 MHz 2.4 GHz 5.7 GHzLMR 400 0.13 0.22 0.355LMR 600 0.082 0.144 0.2381/2 Heliax(LDF4-50A)

0.073 0.13 0.2177/8 Heliax(LDF5-50A)0.043 0.065 N/A5/4 Heliax(LDF 6-50A)0.032 0.048 N/AEIONrecommends81


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94Site Plan Considerations

Determine shadowed areas Avoid interference from adjacent cells Keep antenna cable losses below 6 dB Ensure all permissions acquired


Planning an RF Path - Link BudgetModule # 595Saturday, June 11, 2011

96Link Budget Variables

System Gain EIRP Antenna Gain Propagation Loss Fresnel Zone Cable Loss Path Loss


97System Gain Bit Error Rate (BER) Number of bits in error vs. bits actually sent Target is zero Generally used to establish Receiver Sensitivity For example 80 at a BER of 0 x 10-6 1means that the receiver has a 80 dBm receiver

sensitivityat a 1 bit / million error rate.

System Gain = Transmit Power (dBm) - ReceiveSensitivity (dBm)

Example - Ultima3 RD System Gain = 21 dBm (TX power) (- 80) (Receiver sensitivity)

System gain = 101 dBSaturday, June 11, 2011

98Calculating EIRP

Effective Isotropic Radiated Power (EIRP) The power radiating from an antenna EIRP

= Transmit Power (dBm) - Cable Loss (dB) -Connector Loss (dB) + Antenna Gain (dBi)

Example AWE 120-24 has Tx power of 20 dBm 10 Meters of LMR 400 cable has a loss of 2.2 dB @ 2.4 GHz

Assume 1 dB for connector loss including Surge Arrestor I have selected an dish antenna with a gain of 19 dBi (TA-2318)

EIRP = 20 dBm - 2.2 dB 1 dB + 19 dBi EIRP = 35.8 dBm


99Working with Antenna Gain

dBi or dBd


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y dBi = x dBd + 2.14 dB Directional antennas are best for point-to-point

applications Example 10 dBd antenna has a gain of 12.14 dBi.


100Calculating Propagation Loss

Losses through space Propagation Loss or Attenuation (dB)

.. = Path Loss Constant + 20 log (dKm)where:dKm = Distance in Kilometers92 dB = Path Loss Constant for 900 MHz100 dB = Path Loss Constant for 2.4 GHz108 dB = Path Loss Constant for 5.7 GHz

Example A 10 Km link at 2.4 GHz has a loss of

= 100 dB + 20 Log (10km)= 100 dB + 20 (1)= 120 dBSaturday, June 11, 2011

Cable Type 915 MHz 2.4 GHz 5.7 GHzLMR 400 0.13 0.22 0.355LMR 600 0.082 0.144 0.2381/2 Heliax 0.073 0.13 0.2177/8 Heliax 0.043 0.065 N/A5/4 Heliax 0.032 0.048 N/A101Calculating Cable Loss

Cable loss is pre-determined Remember connector loss (Generally 1 dB / side) Professional installer required dB loss per meter of some common cables Example:

10 Meters of LMR 600 at 2.4 GHz has a loss of.. = 10 * .144 dB/Meter = 1.44 dBSaturday, June 11, 2011

102Calculating Total Loss

Total RF Loss or attenuation throughout system Total Loss

.. = Tx & Rx Cable Loss + Tx & Rx Connector Loss+ Propagation Loss

Example. Base has 10 Meters of LMR 600, remote has 15 Meters of

LMR 400

The link is 20 Km and operates at 2.4 GHzTotal Loss = (10 * .144) + (15 * .22) + (1) + (1) + (100 + 20 Log (20 Km)).. .. .. = 1.44 dB + 3.3 dB + 2 + (100 + 26).. .. .. = 132.74 dBSaturday, June 11, 2011

103Calculating Fade Margin

Fade Margin Measure of Signal to Noise.


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calculated to compensate for fading in the RF path due toweather conditions or increased noise.

EION Wireless generally recommends a 15 dBminimum in environments with no externalinterference

Fade Margin.... .. = System Gain + Antenna Gain Total LossSaturday, June 11, 2011

104Calculating Fade Margin Scenario

A 2.4 GHz link is required to complete a link of 7 Km (4.2 Miles).The product being used is the AWE 120-24 which has a Txpower of 20 dBm and a Rx sensitivity of 81 dB.

The cable required at the Base site will be 15 Meters of LMR600 (49.2 Feet), and the remote antenna requires 28 Meters( 91.84 feet) of LMR 600 because it must be placed on a tower25 Meters high to get proper Line of Site.

Select the proper antennas required to make a non licensedlink in Canada

Loss Cable Loss = 15 * .144 + 28 * .144 = 2.16 + 4.032 2 (Connector) =

8.2 dB

Path Loss = 100 + 20 (Log 7km) = 100 + 16.9 = 116.9 Total Loss = 116.9 + 8.2 = 125.1 dB System Gain System Gain = 20 dBm (-81) = 101 dB


105Calculating Fade Margin Scenario (Cont)

Select the proper antennas required to make a nonlicensed link in Canada

Total Loss (From Previous) = 125.1 dB System Gain (From Previous) = 101 dB As the fade margin must be greater at least equal to

15 dB, this means that the antenna gains must begreater than the 15 dB fade margin.15 dB


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= 20 - 2.16 - 1 + 19 = 35.84 = Lower than 36 dBm OK No license Required Remote EIRP 20 (Tx Power) (28 * .144) (cable Loss) 1 (Connector Loss) + 21

(Antenna Gain) = 20 4.032 1 +21 = 35.97 = Lower than 36 dBm OK No license Required


Rx SensitivityFrequency (Hz)-10010203040-20-30-40-50-60-70-80-90107

Fade Margin with InterferenceSaturday, June 11, 2011

Rx SensitivityFrequency (Hz)-10010203040-20-30

-40-50-60-70-80-90Noise Floor107Fade Margin with InterferenceSaturday, June 11, 2011

RF SignalRx Sensitivity

Frequency (Hz)-10010203040-20-30-40


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01- RF and Wireless Fundamentals - 12 Jun 2011

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Transcript of 01- RF and Wireless Fundamentals - 12 Jun 2011