A simple topology is described for radio frequency identification (RFID) tags mountable on metal surfaces. The tag is built around a commercial UHF RFID module combining an IC and a coupling loop. The module is placed in the neighbourhood of a slot which is used both to couple the energy from the module to the patch-like antenna and to miniaturise the tag. A read range of almost 4 m is obtained in the 865-868 MHz band with a 1.6 mm low-cost FR4 substrate.Introduction: There is strong interest from many industries in tagging metal items (airplane or automotive parts, metal containers, shelves, pipes etc.) with the UHF RFID technology. The thicknesses of the published designs vary from 170 μm [1] to 1 cm [2] and even more. For the tracking of large high value assets, relatively bulky tags are acceptable to guarantee the required performance and thick antennas ( > 3 mm) can protrude from the mounting surface [2]. Ultra-low-profile metal tags whose thicknesses fall into the sub-mm range (down to 200 μm) are required for flat items to achieve an aesthetic integration (e.g. the thickness of the latest Apple MacBook Air is 3 mm), but only when short read ranges ( < 1 m) are acceptable [1,3]. Antenna thicknesses about 1-2 mm also find applications in numerous use cases, for instance when the tags should be curved for mounting on metallic cylinders (e.g. gas tanks and fire extinguishers) while providing medium to long read ranges (from 3 to 9 m) depending on the substrate characteristics [4,5].The read range degradation is inescapable when the tags are placed above large metallic surfaces especially for small antenna thicknesses. This flows from the simultaneous drop of the antenna efficiency and detuning of its input impedance due to the high parasitic capacitance between the metallic surface and the antenna. Apart from effective multiple folded dipole [6] configurations, most solutions are based on patch type or inverted-F type designs. These antennas use shorting-pins or shorting-walls. It makes their fabrication cost higher than that of normal label-type antennas and excludes them from low-cost mass production with inexpensive materials. In this Letter, we propose a simple design for a cost-effective metal tag dedicated to medium reading distances (up to 4 m) working in the European band (865)(866)(867)(868). This tag uses a module combining a loop excitation and an RFID chip. Performances are competitive with published designs of mid-range tags built on FR4 for equivalent antenna volumes and chip sensitivity, but without shorting points.