searching for the tiniest rf module ?

I m searching for the tiniest rf module that i can find. The module should fit inside a fountain pen. 2.4 or 434mhz ? SHould i consider custom pcb ? target size of the project 5mmx1cm ( including a tilt sensor). Any ideas ?
thx

I'm not sure that even the Ipad has such a tiny rf module as you're making.

I do know that tiny rf receivers are virtually a rule in radio controlled airplanes.

Tiny rf transmitters are available as kits. Or there are websites describing how to make one.

As for what frequency to use... The shorter wavelength can use the smaller antenna.

I assume you'll only use your pen-sized audio snooper for good.

You should go to 2.4GHz, the antenna size is the limiting factor in your design. And the application should be short range (10m max).

I have seen modules inside consumer products (doing teardown) at 2.4GHz that were ~1.5cmx0.8cm, very low cost (estimation in large volume below .5S!) using proprietary RF protocols that embed the printed antenna the transceiver and the xtal + all the passives.

Better results (in small dimentions) are obtained in newest dongle for mouse, also using proprietary RF protocols, as the module has also a microcontroller embedded (the IC is a single one that has radio+uC) and you can see them in any PC store. The dongle has the active part inside the usb connector and the ceramic antenna is only 2mmx2mmx8mm roughly.

Nordic RF tranceiver and SoC are the most used in these applications.

I'm not able to give you directions where to buy these, sorry.

Mazz