This is a little circuit that could be used to track an object up to 400m.
It is essentially an SAW stabilized OOK modulated RF transmitter. The modulation is done with two low frequency ultra low power oscillators that activate the transmitter every two seconds for a short period.
With the setup shown here I got up to 400m range. Current consumption is about 180uA average so it’ll work for a couple of days with the little button cell. Frequency 915MHz.”