Thanks, Harrison and Gene,
Actually this product is going to be deployed in about three months
time in one of our public sectors. And it really gives me and my boss
nightmare every night. For small company like us, there is no choice
but to grab everything we could to deliver.
The original prototype is well designed and tested. the frequency is
433 m. Therefore quarter wave length would be about 17.2 cm, which
would be too long for a commercial handheld product.
Our task is to re-package it and produce. And that is why i need to
modify the antenna. I tested quite a few antennas including loop,
semiloop, modified dipole and microstrip antenna as given in
http://www.rfm.com/corp/appdata/antenna.pdf
I am using copper fold to make the antenna plane and the groundplane.
However, the results is far from satisfactory.
For the above mentioned antennas, i did not changed the matching
network given in the transferred design which caters for 17.2 cm
antenna. Do i need to do so? Thanks.
Sigma montoya