Wireless antenna setup

I recently purchased a Dlink Wireless Airplus G Pci Card 2.4Ghz and a
Yagi 14db antenna. I mounted the antenna on the roof with a relatively
clear shot to my friends house . I'm also using lmr-400 cable. The card
is setup correctly because I pickup my neighbor with the little stubby
the card comes with. I have the antenna and cable to reach my friend.
When I screwed in the new cable my reception was no better with the
expensive antenna and cabling over the stub. Can anyone answer what am I
skipping .


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View this thread: http://www.wirelessforums.org/showthread.php?t=32688
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Make sure your yagi is pointing to the right spot in both direction
and ELEVATION. Also, consider the cable length since it might
attenuate the signal to point that the advantage of a roof mounted
yagi would not be of any significance over a stub. If else fails, look
for a 1W wifi amplifier on eBay. And if you insist in an outdoor
(roof) setup with such amplifier, then consult FCC regulations if you
don't want FBI agents to come knocking at your door.

Cheers


On Nov 19, 4:14 pm, homie.6 <homie.6.30b...@no-mx.wirelessforums.org>
wrote:
> I recently purchased a Dlink Wireless Airplus G Pci Card 2.4Ghz and a
> Yagi 14db antenna. I mounted the antenna on the roof with a relatively
> clear shot to my friends house . I'm also using lmr-400 cable. The card
> is setup correctly because I pickup my neighbor with the little stubby
> the card comes with. I have the antenna and cable to reach my friend.
> When I screwed in the new cable my reception was no better with the
> expensive antenna and cabling over the stub. Can anyone answer what am I
> skipping .
>
> ------------------------------------------------------------------------
> View this thread:http://www.wirelessforums.org/showth...lessforums.org

homie.6 <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

>
> I recently purchased a Dlink Wireless Airplus G Pci Card 2.4Ghz and a
> Yagi 14db antenna. I mounted the antenna on the roof with a relatively
> clear shot to my friends house . I'm also using lmr-400 cable. The card
> is setup correctly because I pickup my neighbor with the little stubby
> the card comes with. I have the antenna and cable to reach my friend.
> When I screwed in the new cable my reception was no better with the
> expensive antenna and cabling over the stub. Can anyone answer what am
I
> skipping .

bi24 was right about antenna aiming, but not about the 1-watt amp. You
don't want to use a 1-watt amp. The largest antenna you can use with a 1-
watt amp would be 6 dBi, legally. But you would end up with a receive
path with 8dB less gain. Typically, you would want to use the highest
gain antenna you can and still stay under the 36 dBm ERP limit.

LMR-400 is 6.8 dB/100 ft. Looking at a 100 foot run to make it easy.
Since the card is 15 dBm (nominally), and a 100 ft cable run....

15 dBm (TX power) - 6.8 dB (cable loss) + 14 dbi (ant gain) = 22.2 dbm
ERP.

Well below the 36 dBm limit. So in this case, you would be allowed to use
a 28'ish dBi antenna. This would give a 14 dB gain (over the original 14
db) on the RX side, while still maintaining a 36 dBm ERP level.

Here is a Operating margin calculator. You need to know the operating
specs of both ends (TX power/cable loss/antenna gain/RX sensitivity).
Note that quick calculators like this are dealing with an ideal world,
and you described your location as a 'relatively clear shot', whatever
that means.....

http://www.simrex.com/site/tools/som.php4

Also keep in mind that tools like this are also intended for 'fixed'
wireless, not mobile.

I'd look at aiming, as was said, and antenna location. Moving the antenna
a couple feet this way or a couple feet that way can make a significant
difference. And be sure the cable length is as short as possible.

At the bottom of this page is a typical pattern for a 14 dBi Yagi-like
antenna.

http://www.sparcotech.com/cgi-bin/co...on&key=PC2415N