antenna detector

Hi,

Does anyone know how it is possible to implement a low-cost effective antenna detector circuit for GSM, UMTS and GPS technologies?
I need material, whitepapers, and possibily reference designs.

Thank you in advance.

N.

http://www.wipo.int/pctdb/images1/PC...7/01052357.pdf

Thank you for the link.
It looks easy and fine, even though cannot be designed without any test on prototypes before...
Do you have anything else?

Thank you once more.