Re: best antenna to go through walls?

On Fri, 20 Jul 2007 18:57:45 -0400, nirad
<nirad.2u1kyq@no-mx.wirelessforums.org> wrote:

>i am trying to extend my wireless network's range so I can work by the
>pool in my building ;)

Wireless doesn't work well under water. For that matter, neither does
your laptop.

>Currently I have a WRT54G (running tomato) with
>the standard antennas and I've been looking for replacement antennas to
>accomplish this.

Lots to chose from.
Hint: The bigger and uglier the antenna, the better they work.

>Here is a sectional drawing showing my current router location and the
>patio/pool area I want to reach:'loft section'
>(http://www.nirad.com/awot/LOFTSECTION.pdf). Note that this is an old
>building and the walls are thick. The walls adjoining the hallway are
>covered in marble on one side, though the front door to each unit is
>etched glass.

What's inside the walls? If it's aluminium foil backed insulation or
lath and plaster, give up now. As I see it from your PDF, you're
going through 4 walls. That's a problem even with more conventional
drywall construction. Offhand, I don't think you have a chance.

>I have no access from my unit to the outside, and I face the opposite
>way so it probably wouldn't do much good. However there are electrical
>outlets in the patio area, so FWIW I can plug-in a small range extender
>when I am out there.

A range extender would need to have a good view of both ends of the
path. I don't see a common area, except perhaps outside the building
through windows.

If the building is on a common AC power line, perhaps power line
networking might be more useful.

>Hawking makes some high-powered directional antennas that are less
>intrusive-looking than the typical Yagi designs. I've been looking at
>these two: '15 dB corner antenna'
>(http://www.newegg.com/Product/Produc...82E16833164110),
>'14dB outdoor antenna'
>(http://www.newegg.com/Product/Produc...82E16833164156)

Dunno. Without a fair idea of how much attenuation you're dealing
with due to the 4 walls, it's impossible to determine the optimum
antenna. Also, you making an assumption that a better antenna will
need to be only at the WRT54G end. That will help, but you can also
dramatically improve things by adding an antenna to your unspecified
model laptop.
<http://repair4laptop.org/wireless_lan_antennae.html>

>Is one of these a good choice for accomplishing this?

Good enough. The problem is that I can't calculate how much gain is
required without knowing how much the walls attenuate the signal.
Perhaps you can borrow an antenna and try it? Just about anything
with gain will do for testing. If you can get any kind of signal with
Netstumbler or Kismet, you have a chance.

>Would an omni
>antenna be better?

Hell no. The reflections will cause problems inside the building.

>I'm not sure how narrow the band is with a
>directional, and I haven't found any omni-directional antennas that are
>very powerful.

For good reason. A 12dBi omni will be about 6+ feet long. Add 3 more
dB of gain and the length doubles.

>Also, I will probably want to position the antenna on the
>opposite side of my loft from my router (a 25' cable run, see drawing).

Actually, the small distance probably doesn't make much difference in
path loss.

>Do I need a special cable for this, and do I need a 500mw booster?

Lay off the repeaters, range extenders, boosters, power amps, etc.
They work in some situations but not one where there's probably very
little signal to work with. Yes, you need special low loss cable. If
you're going 25ft or more across the room, you'll need about 30ft of
LMR-400 coax with N connectors and an N to RP-TNC pigtail adapter.
<http://www.fab-corp.com/home.php?cat=249>
Perhaps you might find it easier to move the WRT54G and use CAT5 for
the data extension? Before you fork out for the coax, try it from the
existing location as I don't think moving the antenna is going to do
much.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 jeffl@comix.santa-cruz.ca.us
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

DTC <no_spam@move_along_folks.foob> hath wroth:

>Jeff Liebermann wrote:
>> Hint: The bigger and uglier the antenna, the better they work.

>Try to explain that to the XYL.

I'm not married, so it's not a problem. However, the current
ladyfriend has already balked at me installing an antenna on her car
for GMRS.

The secret to installing a big ugly antenna on the house rooftop is to
start small. Every few weeks, just add a bit more to the
installation. A taller pipe, a bigger reflector, additional elements,
and phased arrays can always be added slowly. If they can't be
expanded, then perhaps a similar but larger antenna. I would think
the antenna manufacturers would get the clue and sell expandable
(inflatable?) antennas. Anyway, starting small, and growing slowly
works quite well and avoids the instantaneous adverse shock reaction
of a big ugly antenna (that works well).

Unfortunately, I may need to downsize my antenna farm and racks full
of nifty (junk) electronics. Most of the women that have seem my
house ask something like "You live like this?" which implies that some
changes are going to be required. In 1975, the county planning
department hinted that my house might be designated a local eyesore
after I did some remuddling.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558