Aircard yagi antenna help needed

Thats because the antenna is NOT really 24Db of gain and.....
15 feet of RG-58 Coax will lose more signal than the antenna
gains!!!
RG-58 is a sponge at 880Mhz..and even worse at 1900MHZ.

---

› See More: Aircard yagi antenna help needed

szilagyic wrote:
> 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 here: ( 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 main beam of the
> antenna 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...

I'm guessing something about the setup is causing the diversity antenna
system in the card to not select the yagi antenna. Bad coax, bad
antenna, picky card... who knows.

RG58 typically averages 10db per 100 feet loss at 900 MHZ, less at 800. At
15 feet loss would be about .6 db. I work with this stuff every day. My
guess is that a connector is defective, the cable is bad or the card has a
problem. Did he put on his own connectors?

Please back up your "fact" that "15 feet of RG-58 Coax will lose more signal
than the antenna gains!!!"

Dave
http://cgroup.us


"Bob's Backfire Burrito" <[email protected]> wrote in message
news:[email protected]...
> Thats because the antenna is NOT really 24Db of gain and.....
>
> RG-58 is a sponge at 880Mhz..and even worse at 1900MHZ.
>
>

"szilagyic" <[email protected]> wrote in message
news:[email protected]...
> ). It is attached to a 30 ft RG58U coax cable that runs back to a
> TNC-
> to-FME adapter, then to the Sierra card.

Here's your first problem. Assuming that you're using a 1900 MHz signal,
you'll only get about 10% of your signal at the end of 30' run of a stock
RG58 cable. There are some "super" RG58 cables (RG8X Ultra) that work much
better and are much more expensive. Normally, for this length of cable you'd
need a foam dielectric RG8.


>
> 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%.

The other thing you should keep in mind is that your phone won't necessarily
be looking for the strongest signal. The phone will lock onto the cell that
the system tells it to lock onto. In general, a Yagi works best in remote
places like an island where the cell towers you are "working" are all in the
same general direction. They will not work as well in places where the cells
are all around the antenna. No sooner do you get the antenna properly
pointed than the system decides that your phone should be talking to a
different cell.

--
Donald R. Newcomb
DRNewcomb (at) attglobal (dot) net

On Jul 18, 1:08 pm, "Bob's Backfire Burrito"
<[email protected]> wrote:
> Thats because the antenna is NOT really 24Db of gain and.....
> 15 feet of RG-58 Coax will lose more signal than the antenna
> gains!!!
> RG-58 is a sponge at 880Mhz..and even worse at 1900MHZ.

Thanks for the quick reply. That makes perfect sense, I did not
realize RG-58 had that much loss. I have been reading that LMR-400
has a much lower loss, so I will be trying some of that soon.

Thanks again,
--
Chris

On Jul 18, 10:38 pm, "Donald Newcomb" <[email protected]>
wrote:
> "szilagyic" <[email protected]> wrote in message
>
> news:[email protected]...
>
> > ). It is attached to a 30 ft RG58U coax cable that runs back to a
> > TNC-
> > to-FME adapter, then to the Sierra card.
>
> Here's your first problem. Assuming that you're using a 1900 MHz signal,
> you'll only get about 10% of your signal at the end of 30' run of a stock
> RG58 cable. There are some "super" RG58 cables (RG8X Ultra) that work much
> better and are much more expensive. Normally, for this length of cable you'd
> need a foam dielectric RG8.
>
>
>
> > 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%.
>
> The other thing you should keep in mind is that your phone won't necessarily
> be looking for the strongest signal. The phone will lock onto the cell that
> the system tells it to lock onto. In general, a Yagi works best in remote
> places like an island where the cell towers you are "working" are all in the
> same general direction. They will not work as well in places where the cells
> are all around the antenna. No sooner do you get the antenna properly
> pointed than the system decides that your phone should be talking to a
> different cell.
>
> --
> Donald R. Newcomb
> DRNewcomb (at) attglobal (dot) net

Thanks for the reply. I did not realize that the RG-58 has that much
loss. I have also read that LMR-400 would be a good alternative. I
will do some more looking and replace the RG-58 and see how that
works.

Thanks much,
--
Chris

> Thanks for the reply. I did not realize that the RG-58 has that much
> loss. I have also read that LMR-400 would be a good alternative. I
> will do some more looking and replace the RG-58 and see how that
> works.

And use as little of it as possible. You lose more as the cable length
increases. Your best bet may be to use a PCMCIA capable router placed in a
weatherproof enclosure as close as possible the antenna. You can then run
ethernet CAT5 wire up to 300' from there.

On Jul 18, 12:37 pm, szilagyic <[email protected]> wrote:
> Hello,
>
> Recently we purchased acellularyagi 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 here: (http://www.easystreetelectronics.com...on=VIEWPROD&Pr...
> ). 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 main beam of the
> antenna 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


Thank you very much for all of the feedback in this thread. I have
finally swapped out the original RG58U coax with LMR-400, and the
difference is phenominal. At our test location, we were getting
around 40% signal with the RG58U hooked to our yagi. When I swapped
out the RG58U cable with the LMR-400 cable, we got all the way to
100%! So it appears our yagi is working good, too.

Thanks again..........
--
Chris