A device with radio frequency identification (RFID) window for coupling to a mouth of a shopping cart, wherein the device comprises: - a frame that comprises: - a window horizontally crossed by a plurality of light rays coming from a light curtain, the window having a width between 330 mm and 550 mm; - an infrared sensor located on any one of the sides of a framework of the window, - an RFID reader connected to at least two UHF antennas (21, 24), where the UHF antennas are located on opposite sides of the framework of the window and directed upward with an angle "α" over the frame between 0° and 26° configured for emitting a radiation beam occupying a volume of space over the window, having each UHF antenna a radiation beam width "ß" between 80° and 150°; - a processor connected to the infrared sensor, to the light curtain and to the RFID reader, where the infrared sensor is configured to detect at least one object that approaches the window; the UHF antennas are configured to be activated once the infrared sensor detects the at least one object that approaches; the RFID reader is configured to detect and identify an EPC code of RFID tags incorporated in the objects that enter or exit the cart through the window; and the light curtain is configured to detect any object that passes through it, and the processor is configured to store the objects that stay within the cart in an electronic shopping list; wherein the frame further comprises a first power supply circuit configured to electrically disconnect the device with RFID window when a plurality of carts are stacked, each shopping cart comprising - a separator part; and - a guide that comprises a spring on the inside thereof and a conducting metallic part; where upon stacking the plurality of carts, the separator part of a first stacked cart is configured to be introduced in the guide of a second stacked cart compressing the spring with the metallic conducting part, thus opening said first power circuit. - a frame that comprises: - a window horizontally crossed by a plurality of light rays coming from a light curtain, the window having a width between 330 mm and 550 mm; - an infrared sensor located on any one of the sides of a framework of the window, - an RFID reader connected to at least two UHF antennas (21, 24), where the UHF antennas are located on opposite sides of the framework of the window and directed upward with an angle "α" over the frame between 0° and 26° configured for emitting a radiation beam occupying a volume of space over the window, having each UHF antenna a radiation beam width "ß" between 80° and 150°; - a processor connected to the infrared sensor, to the light curtain and to the RFID reader, where the infrared sensor is configured to detect at least one object that approaches the window; the UHF antennas are configured to be activated once the infrared sensor detects the at least one object that approaches; the RFID reader is configured to detect and identify an EPC code of RFID tags incorporated in the objects that enter or exit the cart through the window; and the light curtain is configured to detect any object that passes through it, and the processor is configured to store the objects that stay within the cart in an electronic shopping list; - a window horizontally crossed by a plurality of light rays coming from a light curtain, the window having a width between 330 mm and 550 mm; - an infrared sensor located on any one of the sides of a framework of the window, - an RFID reader connected to at least two UHF antennas (21, 24), where the UHF antennas are located on opposite sides of the framework of the window and directed upward with an angle "α" over the frame between 0° and 26° configured for emitting a radiation beam occupying a volume of space over the window, having each UHF antenna a radiation beam width "ß" between 80° and 150°; - a processor connected to the infrared sensor, to the light curtain and to the RFID reader, where the infrared sensor is configured to detect at least one object that approaches the window; the UHF antennas are configured to be activated once the infrared sensor detects the at least one object that approaches; the RFID reader is configured to detect and identify an EPC code of RFID tags incorporated in the objects that enter or exit the cart through the window; and the light curtain is configured to detect any object that passes through it, and the processor is configured to store the objects that stay within the cart in an electronic shopping list; - a separator part; and - a guide that comprises a spring on the inside thereof and a conducting metallic part; where upon stacking the plurality of carts, the separator part of a first stacked cart is configured to be introduced in the guide of a second stacked cart compressing the spring with the metallic conducting part, thus opening said first power circuit.