cell phone antenna
 

greetings,

i am trying to build an external antenna for my cp. i have found
serveral programs from the net about antenna designing so i might try
them but my problem is this, how will i connect the coax cable to my
cell phone. it does not have a whip antenna. when i opened the case i
found a metal in the upper back portion of it. this is maybe the cell
phone's antenna. so is there a way i can connect my external antenna to
this type of cell phone? what is the impedance of a cell phone because
i read that the impedance of the antenna and the feeding device should
be same. any suggestion would be greatly appreciated.

thanks in advance,

ian
philippines

If your OK with the possibilty of ruining the phone!
... you can try to solder a short pigtail of coax to the antenna points you see
in the phone. Put a BNC on the end of the pigtail and use this to connect any
type of experimental antenna you like.

I dont know about in the Phillipines, but most cell phone operate on several
frequency bands, so the antenna is a compromise. If for instance the frequencies
are 900mhz and 2400mhz then you need to force the phone to operate on say 900
then attach a properly tuned antanna for 900mhz. Likewise for 2400mhz. A
resonant half wave dipole for 900 mhz will be about 33cm (or a quarter wave
vertical would be about 16cm tall with radials of 16cm). Directional antennas
would be better but they are more critical to build and adjust.

One way to solve your problem might be to sit on the roof to talk, that way you
get gain by your height.

Another way might be locate the phone up high, and use a remote headset, and use
voice commands to dial out. You still get the benefit of height but can stay
inside.

You could put the phone in the focus of a corner reflector or parabolic dish
pointed at the cell tower. The phone is the radiator and the dish gives you
gain. This is probably the ideal setup if you are stationary in not mobile.

Note: Any time you try to remote the antenna you need a length of coax between
the phone and the antenna. At these frequencies, 50ft of even excellent coax
(1/2" diameter) will likely completly ruin any gain the antenna may give you.
You would only be eliminating some sources of noise by getting up away from the
house. Directional antennas give +gain and the neccessary coax gives -gain but
hopefully not as much, so you come out ahead.




"yhan" wrote in message
ups.com...
greetings,

i am trying to build an external antenna for my cp. i have found
serveral programs from the net about antenna designing so i might try
them but my problem is this, how will i connect the coax cable to my
cell phone. it does not have a whip antenna. when i opened the case i
found a metal in the upper back portion of it. this is maybe the cell
phone's antenna. so is there a way i can connect my external antenna to
this type of cell phone? what is the impedance of a cell phone because
i read that the impedance of the antenna and the feeding device should
be same. any suggestion would be greatly appreciated.

thanks in advance,

ian
philippines

thanks for the advise. the shielded wire i think should be connected to
the cellphone's ground. but i can't see the ground. every metal inside
seems have continuity. maybe, its antenna is only radiator.i am not
sure.any advise where to place the shield wire of coax. how about a
cellphone's impedance?

thanks,

"tjs" bravely wrote to "All" (06 Sep 05 13:29:42)
--- on the heady topic of " cell phone antenna"

Say we point a yagi cut for 900MHz or 2.4GHz at the tower and instead
of using a coax to connect to the cellphone we use a balun to match a
small vertical directly connected to it. Then use the cellphone in
proximity to the yagi/balun/vertical combined antenna. If the yagi has
say +12dB gain then won't the vertical reradiate and recieve with that
added gain or is this one of those perpetual motion impossible gizmos?

A*s*i*m*o*v


tj From: "tjs"
tj Services Xref: core-easynews rec.radio.amateur.antenna:216297

tj If your OK with the possibilty of ruining the phone!
tj .. you can try to solder a short pigtail of coax to the antenna points
tj you see in the phone. Put a BNC on the end of the pigtail and use this
tj to connect any type of experimental antenna you like.

tj I dont know about in the Phillipines, but most cell phone operate on
tj several frequency bands, so the antenna is a compromise. If for
tj instance the frequencies are 900mhz and 2400mhz then you need to force
tj the phone to operate on say 900 then attach a properly tuned antanna
tj for 900mhz. Likewise for 2400mhz. A resonant half wave dipole for 900
tj mhz will be about 33cm (or a quarter wave vertical would be about 16cm
tj tall with radials of 16cm). Directional antennas would be better but
tj they are more critical to build and adjust.
tj One way to solve your problem might be to sit on the roof to talk,
tj that way you get gain by your height.

tj Another way might be locate the phone up high, and use a remote
tj headset, and use voice commands to dial out. You still get the benefit
tj of height but can stay inside.

tj You could put the phone in the focus of a corner reflector or
tj parabolic dish pointed at the cell tower. The phone is the radiator and
tj the dish gives you gain. This is probably the ideal setup if you are
tj stationary in not mobile.
tj Note: Any time you try to remote the antenna you need a length of coax
tj between the phone and the antenna. At these frequencies, 50ft of even
tj excellent coax (1/2" diameter) will likely completly ruin any gain the
tj antenna may give you. You would only be eliminating some sources of
tj noise by getting up away from the house. Directional antennas give
tj +gain and the neccessary coax gives -gain but hopefully not as much, so
tj you come out ahead.



tj "yhan" wrote in message
tj ups.com...
greetings,

i am trying to build an external antenna for my cp. i have found

.... Bad day: When the bird singing outside is a buzzard!