A device for detecting and localizing in a confined manner one or more radio devices which might be present in an enclosed or semi-open area of prohibition, characterized in that it comprises at least the following elements: at least one linear aerial comprising several orifices Oi designed to allow the capture of the signals emitted by the prohibited radio device or devices then their transmission via the linear aerial to a receiving device connected to the linear aerial via a connector, the receiving device being adapted to process the signals sensed by the linear aerial in order to detect the presence of prohibited devices in said area and to reject the detections of the authorized devices outside of said area, and in that the receiving device comprises at least two detection thresholds Seuil j,f and Seuil' j,f, the value of the threshold Seuil j,f is adapted so that the value of the power received P(r,l) j,f at the detection device is such that the ratio P(r,l) j,f /N j,f is higher than the detection threshold Seuil j,f for the carriers employed by the transmitters of the illicit devices considered at the points M(r,l) inside of the area of prohibition, with: 10. log 10 P 0, j, f − C r 0 − P '. I − I 0 − 10. log 10 r / r 0 − 10. log 10 N j, f ≥ 10. log 10 Seuil j, f + η where. r, l, are the radial and linear coordinates of a point M,. l 0 denotes a reference linear distance,. r 0 denotes a reference radial distance to the linear element,. P' denotes the rate of the linear losses along the radiating aerial starting from the distance l 0,. -C(r 0) denotes the coupling losses in the band B j,f at the reference radial distance,. N j,f denotes the receiver noise in the band B j,f,. P 0,j,f denotes the power radiated at the point M(r,l) in the band B j,f,. Seuil j,f represents the sensitivity threshold of the receiving device in the band B j,f, adjusted in order to obtain the confinement of the detection,. η represents a safety margin taking into account the additional attenuations of the signal when it propagates from the prohibited terminal to the aerial, and the value of the threshold Seuil' j,f is such that: 10. log 10 P S, j, f − 20. log 10 R − 10. log 10 N j, f ≤ 10. log 10 Seuil ', j, f − η ' where. R is the distance from the point M, outside of the area of prohibition, to the phase center of the linear aerial,. P S,j,f denotes the power radiated at the point M by the permissible terminals outside of the area of prohibition, in the band B j,f,. Seuil',j,f represents a non-detection threshold of the receiving device in the band B j,f, adjusted according to the gain of the linear element in order to obtain the confinement of the detection to the area of prohibition,. η' represents a safety margin taking into account excesses of power at transmission.. r, l, are the radial and linear coordinates of a point M,. l 0 denotes a reference linear distance,. r 0 denotes a reference radial distance to the linear element,. P' denotes the rate of the linear losses along the radiating aerial starting from the distance l 0,. -C(r 0) denotes the coupling losses in the band B j,f at the reference radial distance,. N j,f denotes the receiver noise in the band B j,f,. P 0,j,f denotes the power radiated at the point M(r,l) in the band B j,f,. Seuil j,f represents the sensitivity threshold of the receiving device in the band B j,f, adjusted in order to obtain the confinement of the detection,. η represents a safety margin taking into account the additional attenuations of the signal when it propagates from the prohibited terminal to the aerial, and. R is the distance from the point M, outside of the area of prohibition, to the phase center of the linear aerial,. P S,j,f denotes the power radiated at the point M by the permissible terminals outside of the area of prohibition, in the band B j,f,. Seuil',j,f represents a non-detection threshold of the receiving device in the band B j,f, adjusted according to the gain of the linear element in order to obtain the confinement of the detection to the area of prohibition,. η' represents a safety margin taking into account excesses of power at transmission.