The magnetic properties of crystalline superconductors in an externally applied field can be modeled by a system of interacting weak link supercurrent loops. The quantum state of the interacting system is described by a set of integersnj. In each quantum statenthe magnetic flux through each independent loop is quantized. The magnetic field dependence of the energy in each quantum state, E(n, Bext), is computed in terms of classical parameters (mutual inductance matrix), quantum numbersnand the external magnetic fieldBext. Transitions between states are driven by absorption and emission of microwave quanta. Back reaction of the network on the field eliminates ‘frustration.’ The model is applied to bulk and single crystal high‐Tcsuperconductors and the results are in qualitative agreement with microwave absorption experiments. The theory predicts the possibility of energy bands in superconductors.