So I am developing an idea for a project I want to work on. I have a Bluetooth device that I want to use to communicate with multiple robots. I want to have a maximum communication range of 100 meters between the device and the robots. I also do not want my signals to be largely affected by walls within that range. Bluetooth doesn't have those kinds of capabilities, and my device only uses Bluetooth. Radio, on the other hand, does.
So my current thoughts are, I can design a circuit with a Bluetooth receiver, a microcontroller, and a radio antenna. This circuit would act as an intermediary between my Bluetooth device and the robots. Bluetooth messages would be read by the uc and converted into a packet radio message and vice versa.
The problem is I know very little about radios. I have done some research before posting here, and it has helped give me a better idea of what I am dealing with, but I still have questions like which frequency should I use? How much power? What kind of antenna should I use? I want this circuit to be able to fit into no bigger than a 5cm x 5cm x 0.5cm box. Does that restrict the size of the antenna, or can the antenna loop inside the box allowing it to be as long as the perimeter of the box?
If you guys can answer these questions given this little information, that's great, but I'm more interested in figuring out how I can answer these questions. If you know any good tutorials for designing something like this or if you could give an explanation of how to go about solving this, I would highly appreciate it!
Thanks in advance!