An apparatus comprising: a first electronic component comprising first radio interface circuitry configured to generate a radio frequency signal, and a second electronic component comprising second radio interface circuitry configured to receive the radio frequency signal; wherein the first electronic component is switchable such that in a first mode of operation, the first radio interface circuitry is configured to transmit the generated radio frequency signal via a first antenna, and in a second mode of operation, the first radio interface circuitry is configured to transmit the radio frequency signal to the second electronic component via a constrained radio frequency signal path coupling the first electronic component and the second electronic component; wherein the second electronic component is switchable such that in the first mode of operation, the second radio interface circuitry is configured to receive the generated radio frequency signal via a second antenna, and in the second mode of operation, the second radio interface circuitry is configured to receive the radio frequency signal from the first electronic component via the constrained radio frequency signal path coupling the first electronic component and the second electronic component, and wherein the first electronic component and the second electronic component include authentication circuitry (212;262) configured to inhibit entering the second mode of operation in the absence of an authentication signal passing between the first and the second electronic components. a first electronic component comprising first radio interface circuitry configured to generate a radio frequency signal, and a second electronic component comprising second radio interface circuitry configured to receive the radio frequency signal; wherein the first electronic component is switchable such that in a first mode of operation, the first radio interface circuitry is configured to transmit the generated radio frequency signal via a first antenna, and in a second mode of operation, the first radio interface circuitry is configured to transmit the radio frequency signal to the second electronic component via a constrained radio frequency signal path coupling the first electronic component and the second electronic component; in a first mode of operation, the first radio interface circuitry is configured to transmit the generated radio frequency signal via a first antenna, and in a second mode of operation, the first radio interface circuitry is configured to transmit the radio frequency signal to the second electronic component via a constrained radio frequency signal path coupling the first electronic component and the second electronic component; wherein the second electronic component is switchable such that in the first mode of operation, the second radio interface circuitry is configured to receive the generated radio frequency signal via a second antenna, and in the second mode of operation, the second radio interface circuitry is configured to receive the radio frequency signal from the first electronic component via the constrained radio frequency signal path coupling the first electronic component and the second electronic component, and wherein the first electronic component and the second electronic component include authentication circuitry (212;262) configured to inhibit entering the second mode of operation in the absence of an authentication signal passing between the first and the second electronic components.