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
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
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 - 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
the cable
damping
short distance
Length theoretical:multipleofλ/2
practical: additional adapter,
unknown cable, etc.
► try and error
Building our antenna - Hints
copper oxidises ► use hairspray or similar
attach antenna cable on the back of the spindle aswell
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