brazoayeye:
I have to communicate over ~30m open field and i have like 6 bases.Is there a big difference between antenna orientation?
In an open field you should be able to communicate between a pair or Ardunos over 30m - I have had a pair of the low power modules (with PCB antenna) working at 110m out doors. With the high power modules (with external antenna) that range would be even easier to achieve.
Why would a master-to-several-slaves system not work?
A diagram showing what you want to do and a description of the data flows would be a great help. And simply telling us what the project is.
...R