Further to this question: 434MHz PCB Trace Antenna Design.
If I select a suitable 434MHz PCB antenna design and make two of them, what is the minimum extra circuitry I would require in order to de able to transmit a simple square wave from one to the other over a short distance (e.g. 30cm) ?
(10Hz Square wave) -> (Circuit A) -> (PCB Antenna 1) -> (PCB Antenna 2) -> (Circuit B) -> (10Hz Square wave out)
What could I use for circuits A and B? In this application, I would value simplicity, size and cost over reliability.
Could I literally use a crystal oscillator with enable input for A, and something like an AM radio for B?
Best Answer
RF comm is a regulated medium. There are specific bands in which unlicensed signals may be sent. Even in these unlicensed bands there are limits on output energy.
Just because the carrier is 434 MHz doesn't mean that all of the energy output will be at that frequency. For example a square wave has infinite bandwidth. When a square wave is multiplied by a carrier, it still has infinite bandwidth centred at the carrier frequency.
Real radios need bandwidth filters to ensure that the energy output complies with a spectral mask. So a square wave will only be parts of a square wave when it goes over the air.
That may be enough in your application. Or you may want to consider one of the usual RF packet protocols.