WLAN Antenna

PPS Antenna Tower Uetliberg

Mathias Aebersold

Matthias Bucher

Overview

Introduction to WLAN

Building our own antenna

Demonstration (next time)‏

Conclusion (next time)‏

Introduction to WLAN

Wireless LAN connection over 30-100m

Since 1997

Various standards (a,b,g,n) with different specifications

WiMax

Technology behind WLAN

Modulation: Orthogonal frequency-division multiplexing, Quadrature amplitude modulation

Frequencies: 2.4 and/or 5 GHz

Channels

No encryption per default

WLAN Standards

Source: http://en.wikipedia.org/wiki/IEEE_802.11

Building our antenna

Types

Our choice

Building our antenna

Building our antenna - Types

types

omnidirectional antenna

sector beam antenna

radiated beam antenna

Wlan-antenna-types

examples:

sources:

http://ecx.images-amazon.com/images/I/11NB6H3HJAL._AA240_.jpg

http://www.germes-online.com/direct/dbimage/50036375/Yagi_Antenna.jpg

~ 25°/25°~ 30°360° /30°angle

~10dBi~ 15dBi~ 5dBigain

BiQuadYagiStandard

Our choice

criteria:

easy to build

cheap(er)‏

high power gain

►BiQuad-antenna based on a cd-spindle

Legal aspects

Construction is legal, running it maybe not

frequencies must be between: 2,4 - 2,48

Ghz

limitation: 100mW = 20dBm of transmitting power

BiQuad-Antenna

radiated beam

source: http://www.lecad.uni-lj.si/~leon/other/wlan/biquad/radiation-wire.html

BiQuad-Antenna

Distance radiator – reflector

best at H=0.1315 λ ~120*0.1315=16mm

source: http://www.lecad.uni-lj.si/~leon/other/wlan/biquad/radiation-wire.html

BiQuad-Antenna

Dimension of the radiator

Best at H=0.23 λ29‏~‏mm

source: http://www.lecad.uni-lj.si/~leon/other/wlan/biquad/radiation-wire.html

Building our antenna

What do you need?

Construction/Specifications

Hints

Building our antenna - Material

cd spindle

1 cd

copper wire (~50cm, cross-section: 2.5mm2)‏

a short antenna/coaxial-cable

some tools

Building our antenna - Construction

reflector

preparing the spindle

stick: 18mm (antenna 16mm over ground)‏

rasp a cross

Building our antenna - Construction

antenna

bend radiator

31mm, 29mm

Building our antenna - Construction

the cable

damping

short distance

Length theoretical:‏multiple‏of‏λ/2

practical: additional adapter,

unknown cable, etc.

► try and error

Building our antenna - Construction

putting‏all‏together…

Building our antenna - Hints

copper oxidises ► use hairspray or similar

attach antenna cable on the back of the spindle aswell

Demonstration

Try it out!

Evaluation

It works!

How well?

For which purposes?

Price

Standard vs BiQuad Antenna

Short distance indoor:

Standard

-25dBm -20dBm -54dBm

-24dBm -29dBm

-25dBm -30dBm

-51dBm -48dBm -59dBm

-51dBm -54dBm

-50dBm -69dBm

Antenna BiQuad No Antenna

1m direct

1m sidewards

1m backwards

3m direct

3m sidewards

3m backwards

Standard vs BiQuad Antenna

Long distance outdoor:

1 3 6 10 14 28 32 39 44 50 60

0

10

20

30

40

50

60

70

80

90

Signal/Noise Ratio vs. Distance

Qualität BiQuad

Qualität Standard

Distance in meters

Sig

na

l/No

ise

Ra

tio in

dB

m

Standard vs BiQuad Antenna

Standard:

Indoor usage

Short distances

Multiple clients

Cheap

BiQuad:

Outdoor usage

Long and short distances

Point-to-point connection

Also cheap, but takes some effort to build it

Questions?

more information about our antenna:

vallstedt-networks.de/?Fotogalerien/Quad

Google

Questions?