Trying to setup an offset antenna for wifi

hi recently i found a website
http://watafak.sandluis.com/patula/antenas/dtv.htm that explain how to
use a offset dss antenna for wifi with a usb adapter. So i give it a
try.

I use a 1.1M Channel Master antenna
(http://www.channelmaster.com/pdf/TYPE110.pdf#search='channel%20master%201.1m%20spec ificati%20ons')
and a TRENDnet TEW-424UB adapter. But i dont get results. Anyone have
tryed this method??


please help me

On 19 Aug 2005 09:58:02 -0700, "yahikochan1" <(E-Mail Removed)>
wrote:

>hi recently i found a website
>http://watafak.sandluis.com/patula/antenas/dtv.htm that explain how to
>use a offset dss antenna for wifi with a usb adapter. So i give it a
>try.
>
>I use a 1.1M Channel Master antenna
>(http://www.channelmaster.com/pdf/TYPE110.pdf#search='channel%20master%201.1m%20spec ificati%20ons')
>and a TRENDnet TEW-424UB adapter. But i dont get results.
>
>Anyone have
>tryed this method??

Yes. It sorta works:
http://802.11junk.com/jeffl/pics/ant...primestar.html
I haven't tried it with a USB adapter yet. Do a Google search for
"primestar 802.11" for some ideas.

A few problems you're going to run into:

1. The antenna has to mounted upside-down because the DBS dish mounts
were never designed to be pointed at the horizon.

2. Illumination angle of the feed horn or USB antenna must be
carefully controlled or lose most of your gain.

3. If working correctly, beamwidth will be about 5-8 degrees which is
difficult to aim.

So what results don't you get and how did you test?

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558

put my usb devide just on top of the LNB cuz i understand that there is
the focus then i adjust the elevation to 20 o 10 soo the antena look to
the horizon then i move side to side to see if i get signal but no
good, only 22% of sinal that was the same i get without the antenna soo
i think i dont put the usb too well on the focus.

i think i need to try again ppl say me that this could work. I think i
dont do it to well on the first try.

i dont see the primestar antena upside-down.
the other too comments in dont understand it to well. i will give it a
try soo

here a link of my usb chipset on the FCC database.
https://gullfoss2.fcc.gov/prod/oet/f...ive_or_pdf=pdf

i opened mine yesterday and look the same. I search it thru the FCC ID
soo it have to be the same chipset.

ok my antena is no a pizza size is a 43.3 inches of Diameter

from the links all give me i will read it, but i notice that in one of
the antenna was at 10 angle of elevation i keep mine on 20 that could
be a a big error.

i will need to try it again to post new results but here the specs from
my antenna.

The Channel Master® 1.1m Offset Antenna is a commercial grade product
suitable for receive only applications. The reflector is
thermoset-molded for strength and surface accuracy. Molded into the
rear of the reflector is a network of support ribs which not only
strengthens the antenna, but also helps to sustain its critical
parabolic shape.
The Az/El mount is constructed from heavy-gauge steel to provide a
rigid support to the reflector. The Az/El mount secures the antenna to
a 2.38 in.O.D.mast.An optional 2.38" universal roof/wall mount is
available. A specially formulated powder paint process offers excellent
protection from weather-related corrosion.

RF PERFORMANCE
Effective Aperture 1.1m (43.3in.)
Operating Frequency 11.45 - 12.7 GHz*
Polarization LHCP/RHCP*
Gain @ 12.5 GHz 41.0 dBi (Typical)
3 dB Beamwidth 1.8° (Typical)
Antenna Noise Temperature @ 30° Elevation 45°K (Typical)
* Frequence & Polarization Depending on LNBF

MECHANICAL PERFORMANCE
Reflector Material Glass Fiber Reinforced Polyester
Antenna Optics One-Piece Offset Feed Prime Focus
Mount Type Elevation over Azimuth
Elevation Adjustment Range 10°-70° Continuous Fine Adjustment
Azimuth Adjustment Range 360° Continuous
Mast Pipe Interface 2.38 in. (60 mm) Outside Diameter
Wind Loading Operational 50mi/h (80 km/h)
Survival 100 mi/h (160 km/h)
Temperature -34°C to 52°C
Humidity 0 to 100% (Condensing)
Atmosphere Salt, Pollutants and Contaminant's as Encountered in
Coastal and Industrial Areas
Solar Radiation 360 BTU/h/ft2
Shock and Vibration As Encountered During Shipping and Handling

yahikochan1 <(E-Mail Removed)> wrote:

> from the links all give me i will read it, but i notice that in one of
> the antenna was at 10 angle of elevation i keep mine on 20 that could
> be a a big error.

I have seen diagrams of the DSS offset dishes that show the true aim on the
web. I remember someone stating that they weren't a parabola, but a
portion of a parabola, so that they didn't point where they appeared to be
pointing. I recall that Primestar dishes always seemed to be pointed at
the ground when they were pointed at the satellites.

The indicator on the mast of my DirecTV dish is calibrated for the true aim
when mounted to a vertical pole. If you have yours pointing at 20, that's
a long ways off from directly horizontal, and this is a very narrow
beamwidth. You might move it around while trying to point at a WAP that
you can see easily.

If the surface of the dish is optically reflective, you could point it at
the sun and see the reflection on the feedhorn.

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

On Sat, 20 Aug 2005 16:12:13 +0000 (UTC),
(E-Mail Removed) wrote:

>yahikochan1 <(E-Mail Removed)> wrote:
>
>> from the links all give me i will read it, but i notice that in one of
>> the antenna was at 10 angle of elevation i keep mine on 20 that could
>> be a a big error.

>I have seen diagrams of the DSS offset dishes that show the true aim on the
>web. I remember someone stating that they weren't a parabola, but a
>portion of a parabola, so that they didn't point where they appeared to be
>pointing. I recall that Primestar dishes always seemed to be pointed at
>the ground when they were pointed at the satellites.

The common offset feed vertically eliptical DBS dish has an
interesting geometry. If you look at the dish from the focus, it
appears to be a perfect circle of about 18" in diameter.

The dual LNB horizontally oval dishes, that are about twice as wide as
they are high, are the equivalent of two 18" dishes side by side. The
reflection from the left LNB goes to the opposite (right) side of the
dish. The other side of the dish contributes nothing to the gain.
This is necessary to prevent a "daisy" antenna pattern, which will
pickup spurious rubbish from other satellites.

The less radically oval DBS dish antennas with dual or triple LNB
feeds are a compromise between gain and beamwidth. The design goal is
to keep the beamwidth from both LNB's around 2-3 degrees, while the
antenna is pointed in the same general direction. If you look at the
patterns for dual and triple LNB systems, the 3dB beamwidths are all
around 3-4 degress, but the 10dB beamwidth (an indication of side
lobes) goes from 3-4 degrees for a single LNB, to perhaps 7 degrees
for a triple LNB. It's not a perfect parabola but a good compromise.

Note that all this is for 10-13Ghz. The single LNB dish will probably
work at 2.4Ghz, but methinks the parabola is far too distorted with
the dual and triple dish designs to insure that the phase center is at
one point at 2.4Ghz. I might be wrong, but I'm too lazy to run the
models to be sure.

>The indicator on the mast of my DirecTV dish is calibrated for the true aim
>when mounted to a vertical pole. If you have yours pointing at 20, that's
>a long ways off from directly horizontal, and this is a very narrow
>beamwidth. You might move it around while trying to point at a WAP that
>you can see easily.

There are lots of ways to aim an offset dish. I do a test adjustment
to get the vertical elevation exactly horizontal when mounted on a
perfectly vertical pipe. I can then just spin the dish around to
wherever it's suppose to point and not worry much about vertical
alignment.

>If the surface of the dish is optically reflective, you could point it at
>the sun and see the reflection on the feedhorn.

Ummm... Melted USB dongle perhaps? You could temporarily cover the
dish with aluminium foil and do this experiment. However, I'm not
sure I would want to be at the focus when you try it.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558

What kind of gain could one expect from this type of antenna ?
Also in playing around with this particular model of USB adapter I was
less than impressed with performance as opposed to other actually less
well known brands.
Any idea of the chipset used on this D-Link USB adapter ?


Jeff Liebermann wrote:
> On Sat, 20 Aug 2005 16:12:13 +0000 (UTC),
> (E-Mail Removed) wrote:
>
> >yahikochan1 <(E-Mail Removed)> wrote:
> >
> >> from the links all give me i will read it, but i notice that in one of
> >> the antenna was at 10 angle of elevation i keep mine on 20 that could
> >> be a a big error.
>
> >I have seen diagrams of the DSS offset dishes that show the true aim on the
> >web. I remember someone stating that they weren't a parabola, but a
> >portion of a parabola, so that they didn't point where they appeared to be
> >pointing. I recall that Primestar dishes always seemed to be pointed at
> >the ground when they were pointed at the satellites.
>
> The common offset feed vertically eliptical DBS dish has an
> interesting geometry. If you look at the dish from the focus, it
> appears to be a perfect circle of about 18" in diameter.
>
> The dual LNB horizontally oval dishes, that are about twice as wide as
> they are high, are the equivalent of two 18" dishes side by side. The
> reflection from the left LNB goes to the opposite (right) side of the
> dish. The other side of the dish contributes nothing to the gain.
> This is necessary to prevent a "daisy" antenna pattern, which will
> pickup spurious rubbish from other satellites.
>
> The less radically oval DBS dish antennas with dual or triple LNB
> feeds are a compromise between gain and beamwidth. The design goal is
> to keep the beamwidth from both LNB's around 2-3 degrees, while the
> antenna is pointed in the same general direction. If you look at the
> patterns for dual and triple LNB systems, the 3dB beamwidths are all
> around 3-4 degress, but the 10dB beamwidth (an indication of side
> lobes) goes from 3-4 degrees for a single LNB, to perhaps 7 degrees
> for a triple LNB. It's not a perfect parabola but a good compromise.
>
> Note that all this is for 10-13Ghz. The single LNB dish will probably
> work at 2.4Ghz, but methinks the parabola is far too distorted with
> the dual and triple dish designs to insure that the phase center is at
> one point at 2.4Ghz. I might be wrong, but I'm too lazy to run the
> models to be sure.
>
> >The indicator on the mast of my DirecTV dish is calibrated for the true aim
> >when mounted to a vertical pole. If you have yours pointing at 20, that's
> >a long ways off from directly horizontal, and this is a very narrow
> >beamwidth. You might move it around while trying to point at a WAP that
> >you can see easily.
>
> There are lots of ways to aim an offset dish. I do a test adjustment
> to get the vertical elevation exactly horizontal when mounted on a
> perfectly vertical pipe. I can then just spin the dish around to
> wherever it's suppose to point and not worry much about vertical
> alignment.
>
> >If the surface of the dish is optically reflective, you could point it at
> >the sun and see the reflection on the feedhorn.
>
> Ummm... Melted USB dongle perhaps? You could temporarily cover the
> dish with aluminium foil and do this experiment. However, I'm not
> sure I would want to be at the focus when you try it.
>
>
> --
> Jeff Liebermann (E-Mail Removed)
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> AE6KS 831-336-2558

On 21 Aug 2005 04:55:59 -0700, "(E-Mail Removed)"
<(E-Mail Removed)> wrote:

>What kind of gain could one expect from this type of antenna ?

What antenna? Give me a type, size, and feed, and I'll guess(tm) or
calculate the gain. Did you catch my previous comments on using a USB
dongle as a dish feed?
> http://groups-beta.google.com/group/...7ddbbf5aa01dd7
The problem is the not so minor detail that the USB antenna sprays RF
in all directions, where perhaps 13% of it actually hits the dish and
is reflected in the desired direction. I posted an estimate for an
18" dish. You can scale them to whatever size dish you're using.

>Also in playing around with this particular model of USB adapter I was
>less than impressed with performance as opposed to other actually less
>well known brands.
>Any idea of the chipset used on this D-Link USB adapter ?

The original question was about a TRENDnet TEW-424UB. If you have the
FCCID number, you can lookup the data at:
> https://gullfoss2.fcc.gov/prod/oet/c...ericSearch.cfm
The inside photo should show the chipset used. I also found this URL:
> http://www.mepis.org/node/6631
which notes that it uses the common Zydas ZD1211 chip.

Now, which model DLink USB adapter are you talking about? There was
no Dlink USB adapter mentioned in previous postings.




--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558

Jeff Liebermann <(E-Mail Removed)> wrote:
> (E-Mail Removed) wrote:

>>If the surface of the dish is optically reflective, you could point it at
>>the sun and see the reflection on the feedhorn.

> Ummm... Melted USB dongle perhaps? You could temporarily cover the
> dish with aluminium foil and do this experiment. However, I'm not
> sure I would want to be at the focus when you try it.

I don't have the patience to cook stuff on 2 meter parabolas intended to
cook things. An aluminum foil lined parabola, and I wasn't even suggesting
that, might cause discomfort if _you_ were at the focus, but for judging
where the focus is directed, I don't think there's any danger of melting
anything in a short period of time used to note the direction.

I just checked my DirecTV dish. It has a 0-65 degree elevation range.

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

On Sun, 21 Aug 2005 19:09:40 +0000 (UTC),
(E-Mail Removed) wrote:

>Jeff Liebermann <(E-Mail Removed)> wrote:
>> (E-Mail Removed) wrote:
>
>>>If the surface of the dish is optically reflective, you could point it at
>>>the sun and see the reflection on the feedhorn.
>
>> Ummm... Melted USB dongle perhaps? You could temporarily cover the
>> dish with aluminium foil and do this experiment. However, I'm not
>> sure I would want to be at the focus when you try it.

>I don't have the patience to cook stuff on 2 meter parabolas intended to
>cook things. An aluminum foil lined parabola, and I wasn't even suggesting
>that, might cause discomfort if _you_ were at the focus, but for judging
>where the focus is directed, I don't think there's any danger of melting
>anything in a short period of time used to note the direction.

Hmmm... Seems like a fun project to try. Maybe keep my coffee warm
with a solar heater made from a DBS dish. Maybe a solar concentrator
for my boiling water steam turbine generator. Seems like a nice
dangerous project to recommend to my science fair project students.

>I just checked my DirecTV dish. It has a 0-65 degree elevation range.

Try adjusting it to 0 degrees. Either the arm that holds the LNB
hits the vertical pipe mount, or the dish hits the pipe. Just because
the markings go to zero, doesn't mean the mount will work at that
angle. I have seen odd mounts that will depress to zero. One can
also be fabricated from pipe parts.


--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
AE6KS 831-336-2558