The invention relates to a method of making a composite sheet. A plurality of layers is first assembled, each layer being comprised of an untreated, unidirectional array of strands. The assembled layers are then placed adjacent one another to form an assembled sheet, with adjacent layers being in a non-parallel orientation, and without any of the layers having been treated with a matrix or binding component. The assembled sheet is then impregnated with a matrix component, which comprises a binding component and may also comprise a radiation-absorbing component.