Paul,

it looks that your calculations are correct. The 100mW is total but most of
it (about 85%) is even used up by the rf. One should expect to get at least
20mW rf power and really, directly coupled to the 50 ohm input of a spectrum
analyzer you will get even more than that.

The real big difference arises out of mismaching messured rf output power
with ERP.
Since a 1/4 wavelength aerial which would achieve good performance at 433Mhz
is about 6 to 7 inch in length, it is not that handy to put it in your
pocket. Therefore common remote designs rely on pcb antennas which are small
in size but real worse in performance.

As their characteristics depend only on the pcb layout, you should be happy
to achieve a radiated power of 1 to 3% of your actual rf input after lets
say 3 to 5 design tries.

Germain

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu