A sensor that that can be, but do not have to be, communicatively coupled with luminaires, includes a sensor module having an electronics board and a battery enclosure. The electronics board includes a sensing component, a controller, and a flex antenna. The battery enclosure is couple with the electronics board and includes a base and a side wall having an outer wall surface. The flex antenna is supported on the outer wall surface such that the flex antenna forms a radially outermost portion of the sensor module, and the flex antenna is conformable to a profile of the outer wall surface. In certain aspects, the sensor module is configured to support a power source on the sensor module. In some cases, the sensor is an indoor sensor.