An article having low ac loss includes an elongated substrate having a length and a width; and a plurality of filaments comprising an oxide superconductor extending substantially along the length of the elongated substrate and spaced apart from one other filaments across the width of the elongated substrate, wherein at least one filament crosses over at least one other filament such that the at least one filament occupies a first position across the width of the elongated substrate before the crossover and a second position across the width of the elongated substrate after crossover.