help to solder coax for external antenna on pcmcia cards

Hallo everybody,

i searched a lot but found contrddittory infos on where to connect an
external antenna disabilng the printed one (or two) on the circuit
board. Some says the signal must be taken b4 the capacitor, others
after.. before or after the the signal splits?

can someone give me a hint ?

see my card here:

http://www.an4a.com/wifi-card-external-antenna_2.jpg
http://www.an4a.com/wifi-card-external-antenna_1.jpg


tnx in advance

happyCoder <lhenry@lhenry.com> wrote in news:ad88b726-7286-433b-a371-
314e80f4eb3e@x41g2000hsb.googlegroups.com:

> http://www.an4a.com/wifi-card-external-antenna_2.jpg
> http://www.an4a.com/wifi-card-external-antenna_1.jpg

Forbidden!

You don't have permission to access /wifi-card-external-antenna_2.jpg on
this server.

On Oct 25, 4:56*pm, DanS <t.h.i.s.n.t.h....@a.d.e.l.p.h.i.a.n.e.t>
wrote:
> happyCoder <lhe...@lhenry.com> wrote in news:ad88b726-7286-433b-a371-
> 314e80f4e...@x41g2000hsb.googlegroups.com:
>
> >http://www.an4a.com/wifi-card-external-antenna_2.jpg
> >http://www.an4a.com/wifi-card-external-antenna_1.jpg
>
> Forbidden!
>
> You don't have permission to access /wifi-card-external-antenna_2.jpg on
> this server.

arghh sorry,

now jpgs are readable..

On Oct 25, 8:21*am, happyCoder <lhe...@lhenry.com> wrote:
> Hallo everybody,
>
> i searched a lot but found contrddittory infos on where to connect an
> external antenna disabilng the printed one (or two) *on the circuit
> board. Some says the signal must be taken b4 the capacitor, others
> after.. *before or after the the signal splits?
>
> can someone give me a hint ?
>
> see my card here:
>
> http://www.an4a.com/wifi-card-extern...-antenna_1.jpg
>
> tnx in advance

I'm not sure if there is any good answer here. The antennas have a
shorted matching stub. You can see the trace terminate at the ground
plane. So how do you know the RF is set up for say 50 ohms? I guess
the question here is do you want the thing to more or less work, or
work well?

If work more or less is the answer, I would first determine which
antenna is used for transmitting. Manny of these cards receive on
either antenna, but only transmit on one.

It would be far simpler just to buy a card with a RF jack. There is
much effort involved in building an antenna, so unless your time has
no value, I wouldn't mess with this card.

On Sat, 25 Oct 2008 08:21:06 -0700 (PDT), happyCoder
<lhenry@lhenry.com> wrote:

>Hallo everybody,
>
>i searched a lot but found contrddittory infos on where to connect an
>external antenna disabilng the printed one (or two) on the circuit
>board. Some says the signal must be taken b4 the capacitor, others
>after.. before or after the the signal splits?
>
>can someone give me a hint ?
>
>see my card here:
>
>http://www.an4a.com/wifi-card-external-antenna_2.jpg
>http://www.an4a.com/wifi-card-external-antenna_1.jpg

Did you remove the PIN diode switch chip (6 pin IC at the junction of
the two antenna feed traces) or is the chip on the other side of the
board?

I would remove the PIN diode switch, which is only useful for
diversity receive, and attach the antenna to a coax pigtail to the
trace coming out of the radio section (shield). The switch and PCB
traces are good for a few dB of loss, which connecting directly should
eliminate. However, there may be DC on the lead from the radio so it
goes through a small value ceramic capacitor at the very end of the
trace. Keep the exposed coax leads very very very very short.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

> Did you remove the PIN diode switch chip (6 pin IC at the junction
of
> the two antenna feed traces) or is the chip on the other side of the
> board?

hallo Jeff,
no I did not removed any chip and there is no chip on the other side,
image 1 shows it clearer than image 2

>
> I would remove the PIN diode switch, which is only useful for
> diversity receive, and attach the antenna to a coax pigtail to the
> trace coming out of the radio section (shield). *The switch and PCB
> traces are good for a few dB of loss, which connecting directly should
> eliminate. *However, there may be DC on the lead from the radio so it
> goes through a small value ceramic capacitor at the very end of the
> trace. *Keep the exposed coax leads very very very very short.

plz clarilfy: do I should connect a capacitor at the end of the trace
out of the rf box ,and then the coax ?

but what about that unsoldered place for - i think - a female board
connector noticeabe in the middle of the card ?
il has gnd and singal ready to be soldered to the coax.

@sushi.com, anyway this is a spare card and I want to solder a pigtail
with female, I already own antenna with male connector

tnx guys!

On Tue, 28 Oct 2008 17:06:31 -0700 (PDT), happyCoder
<lhenry@lhenry.com> wrote:

> > Did you remove the PIN diode switch chip (6 pin IC at the junction
>of
>> the two antenna feed traces) or is the chip on the other side of the
>> board?

>no I did not removed any chip and there is no chip on the other side,
>image 1 shows it clearer than image 2

That area is otto focus in both pictures. Looking at the otto focus
photos, it looks like the center trace (from the RF box) goes nowhere.
Does this board currently function? It looks like the PIN diode
switch is literally missing and the center trace (from the RF can)
goes nowhere.

For my own curiosity, it would be interesting to know the maker and
model number. Extra credit for supplying the FCC ID number so I can
look at the photos on the FCC ID web pile and see if the diversity
switch is present.

>> I would remove the PIN diode switch, which is only useful for
>> diversity receive, and attach the antenna to a coax pigtail to the
>> trace coming out of the radio section (shield). *The switch and PCB
>> traces are good for a few dB of loss, which connecting directly should
>> eliminate. *However, there may be DC on the lead from the radio so it
>> goes through a small value ceramic capacitor at the very end of the
>> trace. *Keep the exposed coax leads very very very very short.
>
>plz clarilfy: do I should connect a capacitor at the end of the trace
>out of the rf box ,and then the coax ?

See the trace coming out of the RF box? At the very end of the trace,
sorta in the middle of where the PIN diode diversity switch would
normally sit, goes a chip capacitor. No clue as to the exact value
but 10pf is about the maximum. The other end goes to the center lead
of your coax pigtail, unspecified connector type, or whatever you're
attaching.

>but what about that unsoldered place for - i think - a female board
>connector noticeabe in the middle of the card ?
>il has gnd and singal ready to be soldered to the coax.

Yep. That's the "test connector". On most boards, there's a Hirose
U-FL connector for the purpose. On your board, it's also missing. You
could use the test pads *IF*:
1. You can disable the diversity switch in software or with a
soldering iron.
2. You can tolerate the extra loss of the PCB traces, diversity
switch, and possibly the matching circuitry.
3. You can somehow disable the existing PCB antennas.
4. You can find a suitable connector that fits the pad pattern.
5. You can keep the connector or exposed pigtail leads VERY short.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Oct 29, 3:59*am, Jeff Liebermann <je...@cruzio.com> wrote:
> On Tue, 28 Oct 2008 17:06:31 -0700 (PDT), happyCoder
>
> <lhe...@lhenry.com> wrote:
> > > Did you remove the PIN diode switch chip (6 pin IC at the junction
> >of
> >> the two antenna feed traces) or is the chip on the other side of the
> >> board?
> >no I did not removed any chip and there is no chip on the other side,
> >image 1 shows it clearer than image 2
>
> That area is otto focus in both pictures. *Looking at the otto focus
> photos, it looks like the center trace (from the RF box) goes nowhere.
> Does this board currently function? *It looks like the PIN diode
> switch is literally missing and the center trace (from the RF can)
> goes nowhere.
>
> For my own curiosity, it would be interesting to know the maker and
> model number. *Extra credit for supplying the FCC ID number so I can
> look at the photos on the FCC ID web pile and see if the diversity
> switch is present.
>
> >> I would remove the PIN diode switch, which is only useful for
> >> diversity receive, and attach the antenna to a coax pigtail to the
> >> trace coming out of the radio section (shield). *The switch and PCB
> >> traces are good for a few dB of loss, which connecting directly should
> >> eliminate. *However, there may be DC on the lead from the radio so it
> >> goes through a small value ceramic capacitor at the very end of the
> >> trace. *Keep the exposed coax leads very very very very short.
>
> >plz clarilfy: do I should connect a capacitor at the end of the trace
> >out of the rf box ,and then the coax ?
>
> See the trace coming out of the RF box? *At the very end of the trace,
> sorta in the middle of where the PIN diode diversity switch would
> normally sit, goes a chip capacitor. *No clue as to the exact value
> but 10pf is about the maximum. *The other end goes to the center lead
> of your coax pigtail, unspecified connector type, or whatever you're
> attaching.
>
> >but what about that unsoldered place for - i think - *a female board
> >connector noticeabe in the middle of the card ?
> >il has gnd and singal ready to be soldered to the coax.
>
> Yep. *That's the "test connector". *On most boards, there's a Hirose
> U-FL connector for the purpose. *On your board, it's also missing. You
> could use the test pads *IF*:
> 1. *You can disable the diversity switch in software or with a
> soldering iron.
> 2. *You can tolerate the extra loss of the PCB traces, diversity
> switch, and possibly the matching circuitry.
> 3. *You can somehow disable the existing PCB antennas.
> 4. *You can find a suitable connector that fits the pad pattern.
> 5. *You can keep the connector or exposed pigtail leads VERY short.
>
> --
> Jeff Liebermann * * je...@cruzio.com
> 150 Felker St #D * *http://www.LearnByDestroying.com
> Santa Cruz CA 95060http://802.11junk.com
> Skype: JeffLiebermann * * AE6KS * *831-336-2558

Depending on the antenna design, the DC could be tolerated. For
example, if it just went to a whip, I don't think DC would be an
issue. A biquad would be a problem.

It looks like there are AC coupling caps at both antennas. That is, it
goes through a cap, then sees a cap shunt. An inductor shunt as well,
not that it matters.

I like your idea of just whacking the center trace. Less is more.

On Wed, 29 Oct 2008 19:36:28 -0700 (PDT), miso@sushi.com wrote:

>Depending on the antenna design, the DC could be tolerated. For
>example, if it just went to a whip, I don't think DC would be an
>issue. A biquad would be a problem.

I wasn't thinking so much about what happens when he attaches a
grounded or DC short type antenna. That would certainly be a problem.
I was thinking about zapping the RF circuitry inside the RF can with a
static blast when I touched the antenna. I've done this a few times
(mostly with GPS prototypes). The small capacitor limits the energy
that can be delivered from the antenna connector.

>It looks like there are AC coupling caps at both antennas. That is, it
>goes through a cap, then sees a cap shunt. An inductor shunt as well,
>not that it matters.

Did you notice the missing diversity switch IC? How does this thing
work?

>I like your idea of just whacking the center trace. Less is more.

Yep.


--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558