patch antenna s11

hi please help me in this......i have designed a microstrip printed dipole antenna that can resonate over multiple frequencies....but with one of the resonating frequency the refflection losses are at -9dB....i tried so much to achieve at -10dB but i just cant do so.....so i am interesting to know that if -9dB is valid or not.....is it good enough or not....and is there something like if s11 is greater than -10dB then the antenna doesnt radiates.....
please help its urgent

Hi,
I think, that - 9dB or -10 dB is not good, better minimal - 15dB, rather -20 dB .... try find on google or http://books.google.com about matching microstrip (or patch) antenna, for example may be:

http://books.google.com/books?id=_er...ennas#PPA24,M1

(page 23 figure 1.13), or united state patent:

http://www.freepatentsonline.com/5233360.pdf ( you must be registered - its free)

Added after 1 hours 33 minutes:

btw what is your band ? Patch antenna is not good for wide-band....

Even 6dB RL is also some time OK with respect to bandwidth requirement. However for narrow band you can achieve better then 10dB. Basically how your system is handling the reflected energy. Do you have mechanism to cancel the multiple reflections?