A coating includes an antenna uniformly distributed in both a matrix and a leuco-dye phase of the coating. A method for preparing an imaging material includes providing a powder having an activator and an antenna, dissolving the activator/antenna powder to form an activator/matrix pre-polymer solution, providing a leuco-dye alloy, and dispersing the leuco-dye alloy into the activator/matrix pre-polymer solution to form a radiation-curable paste. An image-recording medium includes a matrix having an antenna and an activator, and an alloy dispersed in the matrix as an independent phase. The alloy includes an antenna, a leuco-dye, and an accelerator.