microstrip antenna gain and directivity

i design a microstrip antenna its s11 in resonance frequancy is less than 10 db , so can i canclude that my anttena is matched?

i dont know when i design an antenna directivity and gain in which range is acceptable ? for example 4db gain is acceptable?!

With any antenna, gain equals directivity minus loss. Some antennas are resonant and should be tuned for the best matching at a specified frequency (s11 >10 dB). Wideband antennas are considered if their S11 is poorer over the band width.
Low S11 means less RF power supplied from a transmitter is radiated, also in a receiver, some incident power is re-radiated due to the mismatch.
No antenna is perfect, also close objects affect the matching.

many thanks.
in the resonance frequancy my s11 is less than 10db and its gain is 5 db is it acceptable?
do you know after i design my antenna how i can plot e plane and h plane pattern for my antenna?



e plane and h plane pattern in cst simulator

Your antenna may be good for your application. To plot the radiation pattern, you need a test range or an anechoic chamber, with a reference antenna, a signal transmitter and a calibrated receiver. A positioner will rotate the antenna under test in E and H plane and you will record the response.

National metrology laboratory or a university dealing with microwave antennas may offer you such service. In private companies you will have to pay for such test.

there is no way to plot these patterns(e plane pattern and h plane pattern ) with simulators such as cst ?