A system including an implantable medical device. Embodiments of the node device can dynamically vary the power level for the radio in response to communication with other node devices. Weighting structures are connected to passive antenna elements positioned substantially equidistant from the active antenna element. The sliding members are configured to move the divided slab waveguide in their respective mutually-different temperature ranges in the operating temperature range of the arrayed waveguide grating. The bond pad-wiring pattern is formed substantially in a center region of the semiconductor substrate.