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18dBi
/ 24dBi Ex-Galaxy Mod for 2.4Ghz WiFi
How I did my galaxy mod for my
wireless networking
Things you will need when
making your dish
- Ex-Galaxy Dish (18dBi,
24dBi)
- LMR400 Cable
- Male/Female pigtail
connections that suit your Antenna / Wireless Network
Card.
- Solder Iron, and solder.
- Tools: Hacksaw, spanner,
wire cutters, file.
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General
Information
Galaxy Dishs are also
known as conifer antennas.
Most of the antennas
you will find around the suburbs will be
18dBi and 24dBi grid antennas.
Once you have one of
these conifer antennas you just need to mod
the feedhorn so it will work for 802.11b wireless
networking.
Wireless
Links
Links on doing
802.11b wireless network modifications:
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Here
is a list of parts you may need:
Pigtail ends: These ones are for the antenna
connection
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This a lucent connection that would plug in to most
PCMCIA wireless cards.
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How
to Mod a Ex-Galaxy Dish / Conifer Antenna
Important dimensions you need
are:
- Length of the dipole is
1/2 wavelength
- Length of the balun is 1/4
wavelength
- Ratio of inner diameter of
copper tube to outer diameter of brass rod
The 802.11b standard uses
2.412GHz to 2.484GHz frequency range.
The centre of that frequency range makes the 1/2 wavelength
61mm, and 1/4 wavelength is 30.5mm.
Detach Feed Horn
from Galaxy Dish
Back end of pole. |
Mesh Grid. |
The inside of the Feed Horn. |
Detach the feed horn from the mesh dish. (First Image is the
down-converter taken out of feed horn) Next images show how
this is done.
Taking Reflector
off the end of Feed Horn + Gut the insides (down-converter)
Looking down the Feed Horn. |
Same as Left Image but with
down-converter. |
Feed Horn in parts. |
Take the reflector of the end of the feed horn and take the
top end off as shown below. Remove down-convert as shown in
the above images.
Doing the Mod on
the tip of down-converter
Cutting down-converter to make
dipole. |
Ready to solder to coaxial
cable. |
The hole down-converter
circuit board. |
Using the end of the down-converter from the Galaxy's feed
horn measuring 1/2 wavelength which is 64mm of the
down-converter metal tip I cut the 1/4 wavelength which is
half the 1/2 wavelength which makes it 32mm of the circuit
board.
Close enough to the 802.11b
standard. (You could make your own tip up and make it 1/2
wavelength = 61mm & 1/4 wavelength = 30.5mm)
But using the tip of the down-converter makes it fast and easy
to do the galaxy mod.
Solder on the LMR400 cable to
the circuit board, the core goes to the middle part and the
outer core (the wires) go to the left/right parts of the
circuit board.
Doing the Mod on
the tip of down-converter
Put coaxial cable in feed
horn. |
Do this before Soldering Tip
on end. |
Before connecting the cable, make sure you have the cable
through the feed horn before connecting the cable to the tip.
Tip soldered to coaxial cable. |
Close-Up |
Once the cable has been connected to the tip.
Warning Sticker
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You
can be KILLED if this antenna comes near electric
power lines. |
EOF
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