An RF-energy modulation system dynamically adjusts tuned receiving circuits within a plurality of slave devices, thereby regulating the level of power reception in each slave device. The slave devices receive power from a single master device, through coupling of a primary antenna in the master device with a secondary antenna in each slave device. The amount of the power received by each slave device is a function of the antenna separation distance, and is thus different at each slave device location. The RF-energy modulation system monitors the power requirements of the slave device within which the modulation system is included, and modulates the tuning of the secondary antenna to maintain the proper power reception level. Advantageously, such modulation controls the power reception by the slave device, versus dissipating energy already received by the slave device. In a preferred embodiment, the RF-energy modulation system controls the power received by a multiplicity of microstimulators implanted in a single patient.