Antennas on Both Ends?

My question is this, if I add a much larger omni antenna to my access point,
will I have to make any changes to the PCMCIA card in my laptop to take
advantage of it? I guess this could also be phrased, if the antenna is
sensitive enough to pick up data from a node, it should be able to transmit
to that node and be received, and vice versa?

If I can communicate an antenna only on the AP, assuming I have two laptops
that are both capable of reaching the souped up base station, but they are
far enough apart that they should not capable of reaching each other
directly, will the access point (in my case a D-Link DI-614+) be able to
repeat packets?

Thanks.
--
--Andre Masella (andre at masella.no-ip.org, masella.no-ip.org)

One of the most overlooked advantages to computers is... If they do
foul up, there's no law against whacking them around a little.
-- Joe Martin

On Mon, 28 Jul 2003 22:38:42 -0400, Andre Masella <(E-Mail Removed)> wrote:
> My question is this, if I add a much larger omni antenna to my access point,
> will I have to make any changes to the PCMCIA card in my laptop to take
> advantage of it? I guess this could also be phrased, if the antenna is
> sensitive enough to pick up data from a node, it should be able to transmit
> to that node and be received, and vice versa?

Mostly yes, the higher gain antenna will increase both the transmit and
recieve ability of whatever it's attached to and therefore will improve both
ends of the link. There are still times when one end of the link seems to
be able to hear better than the other end (maybe there is a source of noise
near one end but not near the other for example).

>
> If I can communicate an antenna only on the AP, assuming I have two laptops
> that are both capable of reaching the souped up base station, but they are
> far enough apart that they should not capable of reaching each other
> directly, will the access point (in my case a D-Link DI-614+) be able to
> repeat packets?

Yes, that's what APs do. Even if the two laptops are close enough that they
could communicate directly they will still go through the AP.

--
Ray

Thank you - best description of the problem I have read for a long time - I
usually try to explain in the terms of a telescope - yes it appears bigger
but only works in a very small direction. I think that yours is better
though.

If I wanted to make a really good hot spot could I use 2 or more antenna
connected back to back going to 2 or more access points. I was thinking of
using
http://trevormarshall.com/waveguides.htm - or possibly 3 in a triangle
pointing out. Would this work?

> http://trevormarshall.com/waveguides.htm - or possibly 3 in a triangle
> pointing out. Would this work?

Yes using channels 1,6,11 on 3 AP's. You could divide the signal but
AP's are cheap and save dividing the signal out.

"Keith Roberts" <(E-Mail Removed)> wrote in message
news:bg6ro1$42i$(E-Mail Removed)...
> Thank you - best description of the problem I have read for a long time -
I
> usually try to explain in the terms of a telescope - yes it appears bigger
> but only works in a very small direction. I think that yours is better
> though.
>
> If I wanted to make a really good hot spot could I use 2 or more antenna
> connected back to back going to 2 or more access points. I was thinking of
> using
> http://trevormarshall.com/waveguides.htm - or possibly 3 in a triangle
> pointing out. Would this work?
>

Yup, some WISPs use multilple APs each with its own sector antenna. Three
120º sector antennas with three APs on non-overlapping channels provides
excellent 360º coverage, but sucks up all available bandwidth near the site.

I think that's also the purpose of signal splitters -- to maintain proper
load impedance to the radio and allow connection of multiple antennas to one
radio. Unfortunately, the signal splitters degrade the performance of each
antenna and they cost almost as much as another AP (maybe MORE than an AP
when you consider extra cables!) So as long as you have enough available,
non-overlapping channels at the site, your plan is the way to do it.

Don W.

Where can I get some details of the sector antanna that are mentioned. Is it
possible to make at home? Is this the same as patch antenna?

If you split the signal the transmission would go all directions but the
receive should only come through one side - would there be enough signal

Would you have to look at amplifiers to boost the signal so that the maximum
signal level allowed is coming out of each antenna.

I think easiest way is 3 access points to 3 antenna. Would like to try this
but I cant afford this - costs too much at the moment for budget available
(almost none).

Don W. wrote:
> "Keith Roberts" <(E-Mail Removed)> wrote in message
> news:bg6ro1$42i$(E-Mail Removed)...
>> Thank you - best description of the problem I have read for a long
>> time - I usually try to explain in the terms of a telescope - yes it
>> appears bigger but only works in a very small direction. I think
>> that yours is better though.
>>
>> If I wanted to make a really good hot spot could I use 2 or more
>> antenna connected back to back going to 2 or more access points. I
>> was thinking of using
>> http://trevormarshall.com/waveguides.htm - or possibly 3 in a
>> triangle pointing out. Would this work?
>>
>
> Yup, some WISPs use multilple APs each with its own sector antenna.
> Three 120º sector antennas with three APs on non-overlapping channels
> provides excellent 360º coverage, but sucks up all available
> bandwidth near the site.
>
> I think that's also the purpose of signal splitters -- to maintain
> proper load impedance to the radio and allow connection of multiple
> antennas to one radio. Unfortunately, the signal splitters degrade
> the performance of each antenna and they cost almost as much as
> another AP (maybe MORE than an AP when you consider extra cables!)
> So as long as you have enough available, non-overlapping channels at
> the site, your plan is the way to do it.
>
> Don W.

"Keith Roberts" <(E-Mail Removed)> wrote in message
news:bg73tv$7t1$(E-Mail Removed)...
> Where can I get some details of the sector antanna that are mentioned. Is
it
> possible to make at home? Is this the same as patch antenna?
>
> If you split the signal the transmission would go all directions but the
> receive should only come through one side - would there be enough signal
>
> Would you have to look at amplifiers to boost the signal so that the
maximum
> signal level allowed is coming out of each antenna.
>
> I think easiest way is 3 access points to 3 antenna. Would like to try
this
> but I cant afford this - costs too much at the moment for budget available
> (almost none).
>
Here are a couple of good links for some sector antennas:
http://www.superpass.com/2400-2483M.html

http://www.hyperlinktech.com/web/ant...out_sector.php



Here you can find all sorts of splitters:

http://www.hyperlinktech.com/web/signal_splitters.php



Personally, I can't think of a situation where I would use a splitter.
Multiple APs each with its own sector antenna is the way to go, but it does
cost money. If you're trying to set up a WISP, this is the way to do it.
If not, what are you trying to do?



Don W.

Don W. wrote:
> "Keith Roberts" <(E-Mail Removed)> wrote in message
> news:bg73tv$7t1$(E-Mail Removed)...
>> Where can I get some details of the sector antanna that are
>> mentioned. Is it possible to make at home? Is this the same as patch
>> antenna?
>>
>> If you split the signal the transmission would go all directions but
>> the receive should only come through one side - would there be
>> enough signal
>>
>> Would you have to look at amplifiers to boost the signal so that the
>> maximum signal level allowed is coming out of each antenna.
>>
>> I think easiest way is 3 access points to 3 antenna. Would like to
>> try this but I cant afford this - costs too much at the moment for
>> budget available (almost none).
>>
> Here are a couple of good links for some sector antennas:
> http://www.superpass.com/2400-2483M.html
>
> http://www.hyperlinktech.com/web/ant...out_sector.php
>
>
>
> Here you can find all sorts of splitters:
>
> http://www.hyperlinktech.com/web/signal_splitters.php
>
>
>
> Personally, I can't think of a situation where I would use a splitter.
> Multiple APs each with its own sector antenna is the way to go, but
> it does cost money. If you're trying to set up a WISP, this is the
> way to do it. If not, what are you trying to do?
>
>
>
> Don W.
Thanks for the response

Just trying to get my head round some questions at the moment - I would like
to try out some antenna and I saw a cell phone mast yesterday and wondered
if you could do the same thing with wireless networking - seems to be
possible.

Do you have any idea how these sector antenna work - diagrams on how to make
one? I have already got details of other antennas but not this sort.

"Keith Roberts" <(E-Mail Removed)> wrote in message
news:bg8ec7$r9f$(E-Mail Removed)...
> Thanks for the response
>
> Just trying to get my head round some questions at the moment - I would
like
> to try out some antenna and I saw a cell phone mast yesterday and wondered
> if you could do the same thing with wireless networking - seems to be
> possible.
>
> Do you have any idea how these sector antenna work - diagrams on how to
make
> one? I have already got details of other antennas but not this sort.
>
>

It was perceptive of you to bring up cell towers, as that is a good model of
the concept you described.

Sector antennas can be any antenna with a steep cutoff to the sides of the
main lobe. Usually slotted waveguide antennas are used to achieve this. A
search on 'slotted waveguide' will bring up numerous informative links on
Google. The reason you don't find many construction articles on slotted
waveguides is the required precision of the slots. Both position and
dimensions are extremely critical. If you're very good at extremely precise
metalwork, then this kind of antenna will be a piece of cake for you.
Otherwise, you'll find these antennas to be very expensive because of the
precision required to manufacture them. They're really very simple
antennas -- just not easy to cut those slots!

Don W.

Don W. wrote:
> "Keith Roberts" <(E-Mail Removed)> wrote in message
> news:bg8ec7$r9f$(E-Mail Removed)...
>> Thanks for the response
>>
>> Just trying to get my head round some questions at the moment - I
>> would like to try out some antenna and I saw a cell phone mast
>> yesterday and wondered if you could do the same thing with wireless
>> networking - seems to be possible.
>>
>> Do you have any idea how these sector antenna work - diagrams on how
>> to make one? I have already got details of other antennas but not
>> this sort.
>>
>>
>
> It was perceptive of you to bring up cell towers, as that is a good
> model of the concept you described.
>
> Sector antennas can be any antenna with a steep cutoff to the sides
> of the main lobe. Usually slotted waveguide antennas are used to
> achieve this. A search on 'slotted waveguide' will bring up numerous
> informative links on Google. The reason you don't find many
> construction articles on slotted waveguides is the required precision
> of the slots. Both position and dimensions are extremely critical.
> If you're very good at extremely precise metalwork, then this kind of
> antenna will be a piece of cake for you. Otherwise, you'll find these
> antennas to be very expensive because of the precision required to
> manufacture them. They're really very simple antennas -- just not
> easy to cut those slots!
>
> Don W.

I have two links for these slotted design waveguides - one by Trevor
Marshall http://trevormarshall.com/waveguides.htm and another that is a lot
less critical of the tolerance - but I cant find link. Trevor's design is
very precise with square slots cut into the waveguide and the other used
rounded slots - and a simpler antenna feed into the wave guide. If I can
find the time and someone to help me I will try out some of these designs.

Is the cell phone towers using a similar design for the the antenna. I know
that the dimentions will be different due to the different frequencies used.
What sort of power level is used on these antenna? I assume it is higher
than used in 802.11a/b/g.