A system, comprising: - a control module comprising a first antenna, the control module being configured to generate a first radio frequency signal and transmit the first RF signal using the first antenna; - an implantable lead module comprising a second antenna and at least one electrode, the at least one electrode being configured to stimulate an excitable tissue of a subject; and - a relay module configured to: ∘ receive the first RF signal; ∘ generate a second RF signal based on the first RF signal, the second RF signal encoding a stimulus waveform to be applied by the at least one electrode of the implantable lead module to stimulate the excitable tissue of the subject; and ∘ transmit the second RF signal, wherein the relay module comprises: a receive antenna layer, configured to receive the first RF signal transmitted by the first antenna of the control module; at least one dielectric insulating layer; and a transmit antenna layer, separated from the receive antenna layer by the dielectric insulating layer, the transmit antenna layer being configured to transmit the second RF signal to the second antenna of the implantable lead module, the second RF signal being generated based on the first RF signal, and the second RF signal encoding a stimulus waveform to be applied by the at least one electrode of the implantable lead module to stimulate the excitable tissue of the subject, wherein the implantable lead module is configured to receive the second RF signal using the second antenna, generate the stimulus waveform from the received second RF signal, and apply the stimulus waveform to the excitable tissue of the subject. - a control module comprising a first antenna, the control module being configured to generate a first radio frequency signal and transmit the first RF signal using the first antenna; - an implantable lead module comprising a second antenna and at least one electrode, the at least one electrode being configured to stimulate an excitable tissue of a subject; and - a relay module configured to: ∘ receive the first RF signal; ∘ generate a second RF signal based on the first RF signal, the second RF signal encoding a stimulus waveform to be applied by the at least one electrode of the implantable lead module to stimulate the excitable tissue of the subject; and ∘ transmit the second RF signal, wherein the relay module comprises: a receive antenna layer, configured to receive the first RF signal transmitted by the first antenna of the control module; at least one dielectric insulating layer; and a transmit antenna layer, separated from the receive antenna layer by the dielectric insulating layer, the transmit antenna layer being configured to transmit the second RF signal to the second antenna of the implantable lead module, the second RF signal being generated based on the first RF signal, and the second RF signal encoding a stimulus waveform to be applied by the at least one electrode of the implantable lead module to stimulate the excitable tissue of the subject, wherein the implantable lead module is configured to receive the second RF signal using the second antenna, generate the stimulus waveform from the received second RF signal, and apply the stimulus waveform to the excitable tissue of the subject. ∘ receive the first RF signal; ∘ generate a second RF signal based on the first RF signal, the second RF signal encoding a stimulus waveform to be applied by the at least one electrode of the implantable lead module to stimulate the excitable tissue of the subject; and ∘ transmit the second RF signal, a receive antenna layer, configured to receive the first RF signal transmitted by the first antenna of the control module; at least one dielectric insulating layer; and a transmit antenna layer, separated from the receive antenna layer by the dielectric insulating layer, the transmit antenna layer being configured to transmit the second RF signal to the second antenna of the implantable lead module, the second RF signal being generated based on the first RF signal, and the second RF signal encoding a stimulus waveform to be applied by the at least one electrode of the implantable lead module to stimulate the excitable tissue of the subject,