Cellular yagi help needed
 

Hello,

Recently we purchased a cellular yagi dual band antenna to help our
signal strength on a Sierra 860 AirCard with Cingular/AT&T, in hopes
of improving the speed of the card at our home. We are having
horrible results and cannot get it to work correctly. The antenna is
a CCM brand 24 dB dual band yagi (824-896Mhz & 1870-1950Mhz); it was
purchased from he ( http://www.easystreetelectronics.com...PROD&ProdID=71
). It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card. We tried the antenna at a
test location where we know where the tower is at, about 2 miles away,
and can get 90% signal strength with the stock antenna there. When we
attached the yagi and moved it in small increments to each side until
we honed in on the exact spot, the highest signal strength we can get
is about 50-60%. I was assuming we should be able to get 100% signal
strength easily since the stock antenna already gets 90%.

We tried the yagi at another location where we only get about 30%
signal strength with the stock antenna. We do not know where the
tower is at so we started in one spot and went in 5 degree increments
in a complete circle, noting the signal strength at each stop. The
highest we were able to get is about 20%.

We must be missing something here, as I don't see why the yagi has
less signal strength than the stock antenna. I have not tested the 30
ft cable or ends yet, but it was factory made and appears to be fine
(no kinks, etc). The yagi is mounted on a PVC pole, and the elements
of the antenna are vertically oriented, and it the beam is parallel
with the ground.

Can anybody help us or provide some tips??? Are we using the right
antenna? Right now we are completely stumped, and would really like
to get this figured out.

Thank you very much for all feedback and help on this matter...

--
Chris

Cellular yagi help needed
 

"szilagyic" wrote in message
ups.com...
Hello,

Recently we purchased a cellular yagi dual band antenna to help our
signal strength on a Sierra 860 AirCard with Cingular/AT&T, in hopes
of improving the speed of the card at our home. We are having
horrible results and cannot get it to work correctly. The antenna is
a CCM brand 24 dB dual band yagi (824-896Mhz & 1870-1950Mhz); it was
purchased from he (
http://www.easystreetelectronics.com...PROD&ProdID=71
). It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card. We tried the antenna at a
test location where we know where the tower is at, about 2 miles away,
and can get 90% signal strength with the stock antenna there. When we
attached the yagi and moved it in small increments to each side until
we honed in on the exact spot, the highest signal strength we can get
is about 50-60%. I was assuming we should be able to get 100% signal
strength easily since the stock antenna already gets 90%.

We tried the yagi at another location where we only get about 30%
signal strength with the stock antenna. We do not know where the
tower is at so we started in one spot and went in 5 degree increments
in a complete circle, noting the signal strength at each stop. The
highest we were able to get is about 20%.

We must be missing something here, as I don't see why the yagi has
less signal strength than the stock antenna. I have not tested the 30
ft cable or ends yet, but it was factory made and appears to be fine
(no kinks, etc). The yagi is mounted on a PVC pole, and the elements
of the antenna are vertically oriented, and it the beam is parallel
with the ground.

Can anybody help us or provide some tips??? Are we using the right
antenna? Right now we are completely stumped, and would really like
to get this figured out.

Thank you very much for all feedback and help on this matter...

--
Chris


Hi Chris

The performance of your "24 dB Yagi" doesnt surprise me. I have doubts
about the accuracy of the antenna's specs. It wouldnt surprise me to
learn that the CCM antenna had only 10 dB gain over the "stock" antenna.
And coax line loss can vary from manufacturer to manufacturer. Some brands
of RG 58 could have more than 13 dB in the high frequency band.
It could be very difficult to build an antenna with 24 dB Minimum gain
thruout the frequency range 824 to 896 MHz and 1870 to 1950 MHz with one
feed point. A 23 dB "gain" antenna will have a very narrow radiation
pattern beam width. That would require a fairly large antenna at the low
frequency end of your band.

Cellular yagi help needed
 

In article . com,
szilagyic wrote:

It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

Cellular yagi help needed
 

You writes:


It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

I would be more polite but would say 30 ft of RG-58 is an excellent
dummy load at 1900...

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Cellular yagi help needed
 

David Lesher writes:

You writes:


It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

I would be more polite but would say 30 ft of RG-58 is an excellent
dummy load at 1900...

Indeed.

But nonetheless, an el cheapo yagi for 900 MHz GSM with 10 m of RG-58
boosted the indication on my phone from no bars to all 5 bars. The
yagi sees more signal because it is higher up. The yagi gain is
probably just a but more than cable + connector loss. And it looks
like the built in antenna in the phone has a significant negative
gain.

Around here, marginal areas mostly have 900 MHz. So if you need an
external antenna at all, you probably need one for 900.

OP: There has to be something wrong with your antenna system.

73
Jon

Cellular yagi help needed
 

On Jul 17, 4:44 am, LA4RT Jon Kåre Hellan wrote:
David Lesher writes:
You writes:

It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

I would be more polite but would say 30 ft of RG-58 is an excellent
dummy load at 1900...

Indeed.

But nonetheless, an el cheapo yagi for 900 MHz GSM with 10 m of RG-58
boosted the indication on my phone from no bars to all 5 bars. The
yagi sees more signal because it is higher up. The yagi gain is
probably just a but more than cable + connector loss. And it looks
like the built in antenna in the phone has a significant negative
gain.

Around here, marginal areas mostly have 900 MHz. So if you need an
external antenna at all, you probably need one for 900.

OP: There has to be something wrong with your antenna system.

73
Jon

Thanks for the reply. When you say 900 MHz, what frequency range
should I look for, for an antenna? For instance, the one I have now
claims it covers 824-896Mhz, so apparently it doesn't cover 900?

Thank you!
--
Chris

Cellular yagi help needed
 

szilagyic writes:

On Jul 17, 4:44 am, LA4RT Jon KÃ¥re Hellan wrote:
Around here, marginal areas mostly have 900 MHz. So if you need an
external antenna at all, you probably need one for 900.

OP: There has to be something wrong with your antenna system.

73
Jon

Thanks for the reply. When you say 900 MHz, what frequency range
should I look for, for an antenna? For instance, the one I have now
claims it covers 824-896Mhz, so apparently it doesn't cover 900?

Sorry, I wasn't clear enough. And come to think of it, I probably made
some unwarranted assumptions. I'm in Europe. Cell phones here use the
900 MHz band and the 1800 MHz band. All phones are GSM. I believe you
are in the U.S., where there's both GSM, CDMA and some analog, and
frequencies are different. In the U.S., GSM uses the 800 MHz and 1900
MHz bands, and I would expect CDMA to use the same bands.

In the U.S., rural areas are typically covered by 800 MHz networks, as
you want lower frequencies for larger cells. But you'll have to check
if this is actually the case for you. If it is, your antenna is cut
for the right frequency, but there seems to be something wrong with it.

Good luck
Jon

Cellular yagi help needed
 

On Jul 17, 4:44 am, LA4RT Jon Kåre Hellan wrote:
David Lesher writes:
You writes:

It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

I would be more polite but would say 30 ft of RG-58 is an excellent
dummy load at 1900...

Indeed.

But nonetheless, an el cheapo yagi for 900 MHz GSM with 10 m of RG-58
boosted the indication on my phone from no bars to all 5 bars. The
yagi sees more signal because it is higher up. The yagi gain is
probably just a but more than cable + connector loss. And it looks
like the built in antenna in the phone has a significant negative
gain.

Around here, marginal areas mostly have 900 MHz. So if you need an
external antenna at all, you probably need one for 900.

OP: There has to be something wrong with your antenna system.

73
Jon

Hello and thank you for the reply. I had asked around in the groups
originally

(http://groups.google.com/group/alt.c...ar/browse_frm/
thread/3f05f40902745b5/a91191a5bd3d3eb1?lnk=st&q=chris%40groupinfo.com
+frequencies&rnum=12#a91191a5bd3d3eb1)

and was told the frequencies were 800 MHz and 1900 MHz, so this is why
I chose this antenna. For 900 MHz, what frequency range should an
antenna cover to make sure it would work? I will do some more
checking to see if this might be our problem.

Thank you!

Cellular yagi help needed
 

On Jul 17, 4:44 am, LA4RT Jon Kåre Hellan wrote:
David Lesher writes:
You writes:

It is attached to a 30 ft RG58U coax cable that runs back to a TNC-
to-FME adapter, then to the Sierra card.

Only a Dufus, would expect to get ANY signal down 30Ft of RG-58U at those
Frequencies......

I would be more polite but would say 30 ft of RG-58 is an excellent
dummy load at 1900...

Indeed.

But nonetheless, an el cheapo yagi for 900 MHz GSM with 10 m of RG-58
boosted the indication on my phone from no bars to all 5 bars. The
yagi sees more signal because it is higher up. The yagi gain is
probably just a but more than cable + connector loss. And it looks
like the built in antenna in the phone has a significant negative
gain.

Around here, marginal areas mostly have 900 MHz. So if you need an
external antenna at all, you probably need one for 900.

OP: There has to be something wrong with your antenna system.

73
Jon

Thanks for the reply. I did not realize that RG-58 has that much
loss. I have read up and see that LMR-400 is a good alternative. I
will be trying that soon and will post the results.

Thank you!!
--
Chris

Cellular yagi help needed
 

Dear Chris:

Others have pointed out the expected large loss in the RG58 type coax
and the difficulty in designing an antenna to cover the two bands that you
mentioned.

You may find the FCC ID number of your phone/card and go to the FCC's
site to learn the band or bands that your communication device is able to
operate on. It is possible that the device is only able to operate on one
band. I have heard of cases where a device was able to operate on more than
one band but needed the operator to execute an instruction to cause the
device to find the best band. (In other words, apparently some devices do
not ascertain continually what band has the best SNR.)

When you have changed the coax, do report back.

Regards, Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:

"szilagyic" wrote in message
ups.com...
Hello,