"erdem" wrote in message
m...
Actually I am not trying to design antennas ( 500Mhz to 1Ghz- I guess
this gives you information about what sort they are), I am trying to
buy them on a pcb or small chips that could be mounted on a PCB.

Your wavelength of interest is 3cm at a minimum...
you're trying to put them into a box smaller than
that.

How much gain should this antenna have? How
broad-banded does it have to be? How much
power does it have to handle? What kind of
polarization do I want? These are basic
questions you should answer.
__
Steve
KI5YG/EA
..

I am trying to build rf transmitter and receiver that could transfer
information (doors open closed, light on, etc, etc) from my car in the
parking lot to my office desk. The distance is about 100m. I would
like to have the receiver to be very small-key chain size. Therefore I
thought high frequency might result in a smaller antenna. Most
probably bandwidth will be very small (I do not need high speed data
transfer). I am not sure about the polarization issue. About the
power, that depends on the design, most probably. I am planning to use
the IC from; http://www.maxim-ic.com/Wireless.cfm

Is it possible to do this kind of a device that small?

Adam



" Stephen Cowell" wrote in message ...
"erdem" wrote in message
m...
Actually I am not trying to design antennas ( 500Mhz to 1Ghz- I guess
this gives you information about what sort they are), I am trying to
buy them on a pcb or small chips that could be mounted on a PCB.

Your wavelength of interest is 3cm at a minimum...
you're trying to put them into a box smaller than
that.

How much gain should this antenna have? How
broad-banded does it have to be? How much
power does it have to handle? What kind of
polarization do I want? These are basic
questions you should answer.
__
Steve
KI5YG/EA
.

"erdem" wrote in message
om...
I am trying to build rf transmitter and receiver that could transfer
information (doors open closed, light on, etc, etc) from my car in the
parking lot to my office desk. The distance is about 100m. I would
like to have the receiver to be very small-key chain size. Therefore I
thought high frequency might result in a smaller antenna. Most
probably bandwidth will be very small (I do not need high speed data
transfer). I am not sure about the polarization issue. About the
power, that depends on the design, most probably. I am planning to use
the IC from; http://www.maxim-ic.com/Wireless.cfm

Is it possible to do this kind of a device that small?

Easily... as long as all it has to do is receive. You
can pump out 20W of UHF RF from your car, you'll
hear it without any antenna at all inside, probably.
Your concerns are path loss (not that much through
the walls of the building) and receiver antenna
inefficiency (the greater of the two, since you put
a small size limit).

Perhaps you're talking about this chip:

http://www.maxim-ic.com/view_press_r...release_id/932

Pretty impressive, I must say... looks like fun.

Keeping this On Topic for r.r.a.a, I'd start with
a piece of wire 1/4 wave long, run around the
perimeter of your device, as an antenna.
__
Steve
KI5YG/EA
..


PS Make sure that you address any legal considerations
about one-way automatic transmissions.

Adam, before you get all wound up over building a system from scratch, why
not consult some security and alarm companies, and see what they have
available...?

- KI6PR

"erdem" wrote
I am trying to build rf transmitter and receiver that could transfer
information (doors open closed, light on, etc, etc) from my car in the
parking lot to my office desk. The distance is about 100m. I would
like to have the receiver to be very small-key chain size. Therefore I
thought high frequency might result in a smaller antenna. Most
probably bandwidth will be very small (I do not need high speed data
transfer). I am not sure about the polarization issue. About the
power, that depends on the design, most probably. I am planning to use
the IC from; http://www.maxim-ic.com/Wireless.cfm

Is it possible to do this kind of a device that small?

Adam



" Stephen Cowell" wrote in message
...
"erdem" wrote in message
m...
Actually I am not trying to design antennas ( 500Mhz to 1Ghz- I guess
this gives you information about what sort they are), I am trying to
buy them on a pcb or small chips that could be mounted on a PCB.

Your wavelength of interest is 3cm at a minimum...
you're trying to put them into a box smaller than
that.

How much gain should this antenna have? How
broad-banded does it have to be? How much
power does it have to handle? What kind of
polarization do I want? These are basic
questions you should answer.
__
Steve
KI5YG/EA
.

Before I start this circuit, could you guys suggest me any references
to look maybe, about some high freq. rf design tricks, etc

Thanks,
Adam

" Stephen Cowell" wrote in message ...
"erdem" wrote in message
om...
I am trying to build rf transmitter and receiver that could transfer
information (doors open closed, light on, etc, etc) from my car in the
parking lot to my office desk. The distance is about 100m. I would
like to have the receiver to be very small-key chain size. Therefore I
thought high frequency might result in a smaller antenna. Most
probably bandwidth will be very small (I do not need high speed data
transfer). I am not sure about the polarization issue. About the
power, that depends on the design, most probably. I am planning to use
the IC from; http://www.maxim-ic.com/Wireless.cfm

Is it possible to do this kind of a device that small?

Easily... as long as all it has to do is receive. You
can pump out 20W of UHF RF from your car, you'll
hear it without any antenna at all inside, probably.
Your concerns are path loss (not that much through
the walls of the building) and receiver antenna
inefficiency (the greater of the two, since you put
a small size limit).

Perhaps you're talking about this chip:

http://www.maxim-ic.com/view_press_r...release_id/932

Pretty impressive, I must say... looks like fun.

Keeping this On Topic for r.r.a.a, I'd start with
a piece of wire 1/4 wave long, run around the
perimeter of your device, as an antenna.
__
Steve
KI5YG/EA
.


PS Make sure that you address any legal considerations
about one-way automatic transmissions.