RFID-reader-antenna for interrogating at least one RFID-transponder having an item-antenna attached on an item, by sending excitation signals (Ex) to the item-antenna and receiving response signals (Re) from the item-antenna, the signals (Ex, Re) having pre-defined electrical characteristics, the RFID-reader-antenna being adapted to fit into an item-holder that keeps the at least one item with the item-antenna at a position that is limited by the dimension of the item and by the dimension of the item-holder, wherein a) the RFID-reader-antenna has at least a first antenna unit and a second antenna unit implemented as electrically conductive elements that are planar and that are electrically isolated attached to a base, wherein the first antenna unit and the second antenna unit are implemented on the base by coating; b) the base is adapted to be attached to the item-holder, the base being formable for attaching the reader antenna with the item holder by being inserted into the item holder; c) the dimensions of the first antenna unit and of the second antenna unit comply with the following dimension condition: (i) for the pre-defined electrical characteristics of the excitation signals and response signals, and for situations in that the base is actually attached to the item-holder, the first antenna unit and the second antenna unit provide interrogation ranges (169-1, 169-2) that are partially overlapping and that in combination create an overall interrogation range that includes the space in that the item-antenna can be positioned, so that interrogating is possible for any position of the item by at least one of the first antenna unit and of the second antenna unit, wherein the dimension condition is in compliance if the projection (ΔZ) of the item-antenna to the first antenna unit or the projection (ΔZ) of the item-antenna to the second antenna unit is larger than a pre-defined area, for any position of the item. a) the RFID-reader-antenna has at least a first antenna unit and a second antenna unit implemented as electrically conductive elements that are planar and that are electrically isolated attached to a base, wherein the first antenna unit and the second antenna unit are implemented on the base by coating; b) the base is adapted to be attached to the item-holder, the base being formable for attaching the reader antenna with the item holder by being inserted into the item holder; c) the dimensions of the first antenna unit and of the second antenna unit comply with the following dimension condition: (i) for the pre-defined electrical characteristics of the excitation signals and response signals, and for situations in that the base is actually attached to the item-holder, the first antenna unit and the second antenna unit provide interrogation ranges (169-1, 169-2) that are partially overlapping and that in combination create an overall interrogation range that includes the space in that the item-antenna can be positioned, so that interrogating is possible for any position of the item by at least one of the first antenna unit and of the second antenna unit, wherein the dimension condition is in compliance if the projection (ΔZ) of the item-antenna to the first antenna unit or the projection (ΔZ) of the item-antenna to the second antenna unit is larger than a pre-defined area, for any position of the item. (i) for the pre-defined electrical characteristics of the excitation signals and response signals, and for situations in that the base is actually attached to the item-holder, the first antenna unit and the second antenna unit provide interrogation ranges (169-1, 169-2) that are partially overlapping and that in combination create an overall interrogation range that includes the space in that the item-antenna can be positioned, so that interrogating is possible for any position of the item by at least one of the first antenna unit and of the second antenna unit, wherein the dimension condition is in compliance if the projection (ΔZ) of the item-antenna to the first antenna unit or the projection (ΔZ) of the item-antenna to the second antenna unit is larger than a pre-defined area, for any position of the item.