A wireless device comprising a Van Atta array, said Van Atta array comprising a plurality of antenna pairs (A,B;C,D;E,F); each of said antenna pairs comprising two antenna elements (A,B;C,D;E,F) electrically coupled by a signal path of predetermined length (101,102,103); the signal path of each of said antenna pairs having a center point around which the two electrically coupled antenna elements are symmetrically arranged, and the wireless device further comprises a measurement unit, said measurement unit adapted to perform electrical measurements between two measurement points (220,ab,cd), one of said two measurement points (220,ab) being located at a first predetermined location on the signal path of one of the antenna pairs (A,B), and the other of said two measurement points (cd) being located on a second predetermined location on the signal path of one of the other antenna pairs (C,D) and wherein the first predetermined location and the second predetermined location are at non-equal signal lengths from the center point of their respective signal paths, and wherein the measurement unit comprises a directional coupler, the directional coupler is a quadrature hybrid and wherein the first port of the quadrature hybrid is coupled to the first antenna element of one of the antenna pairs of the Van Atta array, the second port of the quadrature hybrid is coupled to the second antenna element of the one of the antenna pairs of the Van Atta array, and wherein the wireless device further comprises a first diode and a second diode, the first diode being coupled to the third port (x) of the quadrature hybrid, and the second diode being coupled to the fourth port (y) of the quadrature hybrid. each of said antenna pairs comprising two antenna elements (A,B;C,D;E,F) electrically coupled by a signal path of predetermined length (101,102,103); the signal path of each of said antenna pairs having a center point around which the two electrically coupled antenna elements are symmetrically arranged, and the wireless device further comprises a measurement unit, said measurement unit adapted to perform electrical measurements between two measurement points (220,ab,cd), one of said two measurement points (220,ab) being located at a first predetermined location on the signal path of one of the antenna pairs (A,B), and the other of said two measurement points (cd) being located on a second predetermined location on the signal path of one of the other antenna pairs (C,D) and wherein the first predetermined location and the second predetermined location are at non-equal signal lengths from the center point of their respective signal paths, and wherein the measurement unit comprises a directional coupler, the directional coupler is a quadrature hybrid and wherein the first port of the quadrature hybrid is coupled to the first antenna element of one of the antenna pairs of the Van Atta array, the second port of the quadrature hybrid is coupled to the second antenna element of the one of the antenna pairs of the Van Atta array, and wherein the wireless device further comprises a first diode and a second diode, the first diode being coupled to the third port (x) of the quadrature hybrid, and the second diode being coupled to the fourth port (y) of the quadrature hybrid.