Telkom Installer Course

Presented by

Poynting Antennas

Andre Fourie

Welcome

▪ Introductions

▪ What we hope to achieve

▪ Theory and Fundementals

▪ Practical Experience

▪ Have fun while doing so

Easy, once you know how

Overview of the Course

▪ Fundementals

▪ Antennas

▪ Radio waves

▪ Cables and Connectors

▪ Modulation and Throughput

▪ Lightning and Earthing

▪ Signal Testing and Surveys

Overview of the Course

▪ Practical Considerations

▪ Waterproofing

▪ Obstructions

▪ Aligning antennas

▪ Mounting antennas

▪ Etiquette

Day 2 : Practical Installation

▪ Hooking up Poynting with WiMAX

Communications Technologies

▪ Move information from one point to another

▪ Progress of communications technologies

▪ Voice - sound (short range, med data rate)

▪ Smoke signals - visual (med range, low data rate)

▪ Drums - sound (med range, low data rate)

▪ Written word - text (long range, v low data rate)

▪ Carrier pigeon - text (long range, low data rate)▪ Called TCP – Transfer by Carrier Pigeon

▪ Telegraph - wires (long range, high data rate)

▪ Radio - radio waves (v long range, v high data rates)

History of Radio

▪ James Clark Maxwell – 1873

▪ Predicted the existance of EM waves

▪ Heinrich Rudolf Hertz - 1887

▪ First person to intentionally transmit and receive EM waves.

▪ Guglielmo Marconi – 1902

▪ First transatlantic transmission

Hertz said…

▪ "It's of no use whatsoever ... this is just an experiment that proves Maestro Maxwell was right - we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there.”

▪ "I do not think that the wireless waves I have discovered will have any practical application."

Fundamentals

▪ Radio Waves

▪ Decibels

▪ Antennas

▪ Cables

▪ Transmitters

▪ Receivers

▪ Transmission of Information

Radio Waves

▪ Introduction/brief history of radio waves

▪ E and H Fields▪ E – electric field▪ H – magnetic field

▪ Propagation▪ Transfer of energy▪ E and H field are always perpendicular▪ Poynting vector

▪ Frequency▪ The number of times an electromagnetic field cycles per

second▪ Measured in Hertz (Hz)

Radio Waves (cont…)

▪ Wavelength

▪ Power▪ Flow of energy over time

▪ Electromagnetic field intensity

(Hertz)frequency

(meters)h wavelengt

secondper meters 000 000 300 light of speed c

)(

300)(

=

=

==

==

f

MHzff

cm

Some questions

▪ Why does 220VAC not create radio waves?

▪ Does lightning create radio waves?

Decibels

)(log10 10 xdB =

= 1010

dB

x

Decibels, why bother?

▪ Two advantages

▪ Compress large and expand small numbers

▪ All multiplication via summation

▪ Example

▪ Decibels relative to a metre

▪ 1m = 0 decibels [dB] relative to a metre [m] OR [dBm]

▪ Oxygen atom = 0.00000000014m OR -98.5 dBm

▪ Sun = 1400000000m OR 91.5 dBm

▪ Man = 1.8m OR 2.6 dBm

Decibels without Calculators

▪ Three rules of dB’s

▪ Rule of 0

▪ Any number compared to itself is 0dB

▪ Rule of 3

▪ Add 3 dB = Multiply by 2

▪ Subtract 3 dB = Divide by 2

▪ Rule of 10

▪ Add 10 dB = Multiply by 10

▪ Subtract 10 dB = Divide by 10

Decibels (cont…)

▪ Example▪ How many dBm in 50W?▪ How many watts in 17dBm?▪ If I have a 12.5dBm signal and I amplify the signal 500 times, what is the

new signal strength in dBm?▪ How much stronger is the signal from a 24dBi antenna compared to a

14dBi antenna?

▪ Decibels relative to one watt dBW▪ Decibels relative to one milliwatt dBm▪ Decibels relative to the gain of an isotropic antenna dBi

Antennas

▪ What is an antenna?

Antennas (cont…)

▪ Do not create energy

▪ Do not amplify signal

▪ Do focus energy

▪ Most important properties

▪ Radiation pattern (focus pattern)

▪ Willingness to accept energy

Radiation pattern

Gain

▪ Derived from the pattern

▪ Amount of power focusing relative to uniform (isotropic) source at direction of maximum focusing

▪ e.g. 4 times more focused than isotropic source at ‘boresight’ is 6 dBi gain

▪ We can also talk about gain in a specific direction

▪ Gain changes with direction

Beamwidth

▪ ‘Half power’ or ‘-3dB’ beamwidth

40o

Polarisation

▪ Linear

▪ Vertical

▪ Horizontal

▪ Circular

Willingness to accept energy

▪ AKA: Matching, VSWR, Return loss

▪ Antennas will generally accept only a certain percentage of incoming energy, the rest will be rejected and sent back!

▪ VSWR is the most common

indicator of this.

VSWR = 1 means accepts everything

VSWR = 2 means accepts 90% power

VSWR = 10 means accepts 2% power

VSWR and frequency

Gain and frequency

▪ Patterns and therefore gain ALSO change with frequency!

Antenna specifications

▪ Frequency

▪ Always look at pattern, not gain

▪ Type of antenna

▪ Make sure gain is consistent over your required frequency

▪ Check for inconsistencies between beamwidth and gain

▪ VSWR is almost always good enough

▪ Check if below 2.5

▪ Beware of ‘specmanship’

WLAN-A0038

▪ Let’s check out the brochure…

Good news!

▪ Reciprocity

Types of antennas

▪ Classified by the type of pattern

▪ Classified by design

▪ Omni’s

▪ Sectors

▪ Patches/Panels

▪ Dishes

▪ Yagi’s

▪ Helicals

▪ Enclosures with integrated antennas

Omni directional antennas

11 dBi outdoor omni pattern5 dBi Indoor omni pattern8 dBi outdoor omni pattern8 dBi outdoor downtilt pattern

Sectors16 dBi 90 degree sector pattern

Patches and panels

8dBi single patch patternQuad patch patternHigh gain panel pattern

Dishes

75cm grid dish pattern

Yagi antennas

Helicals

Enclosures with integrated antennas

Cables

▪ Transmission Lines

▪ Co-axial cable

▪ Impedance

▪ Matching

▪ Losses

Cables (cont…)

NameLoss in dB/m

at 2.4 GHzLoss in dB/m

at 5.8 GHzSize in mm Cost R/m

LMR-400 0.20 0.45 10.30 30

LMR-600 0.13 0.31 15.00 60

RG-58 1.00 2.10 5.00 5

LMR-195 0.55 1.30 4.95 13

RG174 ~2.00 ~5.00 3.00 3

Connectors

▪ Connectors

▪ Establishing sex

▪ Reverse Polarity

▪ Reverse Thread

Radios

▪ Transmitters

▪ Transmitted power [dBm]

▪ Receivers

▪ Receiver sensitivity [dBm]

▪ Transceivers

▪ Cannot RX and TX simultaneously

▪ 2-way Radio

▪ Transceiver and interface

Bits and Bytes on a Radio

▪ Modulation▪ Digital encoding (symbols, bits and baud rate)

▪ The flag analogy

Signal to Noise Ratio

▪ SNR : Signal to Noise Ratio

▪ RSSI : Received Signal Strength Indicator

▪ CINR : Carrier to Interference + Noise Ratio

Signal to Noise Ratio

Demonstration : Signal strength

▪ Symbol Rates and Data Rates

▪ Is it possible to have too much signal strength?

Outdoor propagation

Outdoor propagation (cont…)

▪ The Link Equation

( )22

4 r

GGPP rt

tr

=

Demonstration

▪ The Link Planning Tool

▪ Reality check : Actual radio link

Outdoor propagation (cont…)

▪ Obstructions

▪ Fresnel Zones

Link distance

(km)

r1 in meters

1 5.6

2 7.9

3 9.7

4 11.2

5 12.5

Outdoor propagation (cont…)

▪ Trees and rain

Lightning and surge

Lightning and surge

▪ The Rolling Ball Model

Lightning and surge

▪ Inline Surge Protection

Lightning and surge

▪ Earthing

▪ Voltage Gradients

The end