"steve" <stevesemple@lycos.com> hath wroth:
>Building I suppose is 35 -30 feet high.
Ok, increase the vertical angle to:
Vert angle = 2 * tan-1 (35/125) = 2 * 15.6 deg = 31 degrees
That will be a problem for my recommended AMOS antenna. 44 degrees
horizontal and 31 degrees vertical is almost symmetrical enough to use
a common patch, panel, biquad, coffee can, or similar antenna. I
would also recommend trying a biquad.
>> You're obviously in a college so we're going to do this as a math
>> exercise instead of a shopping exercise.
>Well no college was about 30 years ago for me.
>Didnt have computers when I went to college.
Sorry. Bad guess. However, you still get to do the math. Dust off
your abacus or slide rule (I still use mine ocassionally).
Have you considered getting the students involved in this exercise? In
the past, I was seeing professional installs contracted by the
administration. Recently, I'm seeing a few student inspired and
managed systems.
>> 1. What equipment you currently have?
>Just a wireless us robotics router right now. Mostly doesnt work.
Purchase a router that works.
>> 2. How far into the building you plan to penetrate?
>Prety much whole building but dont mind a few dead spots.
It won't work. You'll get reasonable penetration near the windows and
into the rooms facing the outside but nothing in the interior rooms,
hallways, or rooms on the other side of the building. 2.4GHz does not
penetrate building structures very well. You mention the building is
50ft wide, which I guess(tm) means two rooms and a center hallway. The
hallway and the rooms on the other side of the building are going to
be dead spots.
>> 3. What radios are at the other end of your "broadcasting" (laptops)?
>Not sure what you mean?
It takes two to tango. You have a malfunctional SMC wireless router.
What type of computers are going to be talking to this wireless
router? Laptops? Desktops? Are they going to be able to use
external antennas that can see your malfunctional SMC wireless router?
>> 4. What thruput were you expecting?
>Hadnt that about this. Basically this is just for surfing. We only
>have a dsl line coming to the the school fo offices etc.
It's important because range varies with speed. The slower speeds
will go furthur. You can also trade speed for reliability. My
guess(tm) is that your DSL line run about 1.5Mbits/sec. Therefore, I
suggest a connection speed of 6Mbits/sec 802.11g OFDM which will offer
the most range. This would be a key component of calculating the
whether this will work.
>> 5. Are there any obstructions in the line of sight. In my experience
>No its pretty clear.
>Something someone said above which I wasnt considering was that the
>clients are going to have to send the signal back to the main building
>this sounds like I will need hardware at both ends. eg not just one
>antenna and expect laptops and desktops to reach it. Am I right in my
>thinking? So I would have to buy two antena's and other hardware for
>the residence.
Yes. The clients will need a wireless device of some sort to connect
to your malfunctional SMC wireless router. It takes two to tango.
What John Navas was aluding to was that you should not use a power
amplifier at just one end. It only increases the range in one
direction. It doesn't help if you can't hear the return signals.
Incidentally, such an amplified system is called an "alligator" or an
animal with a big mouth and small ears. If you need more range, it
should be done first with antennas, which increase the gain in BOTH
directions equally.
There's also a realistic limit to how many users can connect to your
system. It really depends on what they're doing. My rule-of-thumb
is:
100 light web and email users
10 business users
1 file sharing user
Think about how you're going to administer and police this system. I
can supply details if interested. Hardware is the least of your
problems.
Suggestions:
1. Find a wireless router that works.
2. Connect literally any directional antenna with a gain between 8
and 12dBi to the wireless router. Place it in the proposed location.
3. Find a laptop and do what's called a site survey. That's where
you walk around and see how well you can connect in the intended
coverage area. If you want to do it with some cool but pricy
software, see:
<http://www.ekahau.com/?id=4600>
Otherwise, use Netstumbler or iStumbler to check for coverage.
4. If building penetration is difficult, give up on wireless, and do
it another way. 150ft is not very far and can easily be handled with
CAT5 or fiber optic cable. If you must have wireless in the
building, sprinkle a few around the building and perhaps use wireless
for a point to point backhaul.
5. If the buildings have a common CATV, phone line system or AC power
line, then these can be used as an alternative method.
http://www.homepna.com http://www.homeplug.com http://www.multilet.com
--
Jeff Liebermann
jeffl@comix.santa-cruz.ca.us
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Which Antenna should I buy ?? 
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