A superconducting microtriangle is proposed to be used as a field-dependent diode. A dc voltage generated by the triangle induced by an applied ac drive is observed close to the superconducting/normal phase boundary. This effect is due to the superposition of the asymmetric screening currents in the triangle and the ac drive. The sign of the dc voltage is an alternating function of the applied magnetic field that reflects switching of the direction of the screening currents in the structure. (c) 2006 American Institute of Physics.