Abstract: A replaceable antenna assembly for use with a piston accumulator configured for supplying fluid to a hydraulic cylinder is provided. The antenna assembly includes a hollow manifold for flow of fluid and an antenna connected into or onto the manifold for emitting and receiving electromagnetic waves. The hollow manifold is connectable to and configured to be in fluid communication with both the piston accumulator at one end and a pressure line at the other end. The pressure line is connectable to an external high pressure gas bank. The antenna assembly further includes at least one first bore for transferring signals to and from the antenna and at least two fluid channels symmetrically displaced around the circumference of the antenna, thereby ensuring that most of, or all, fluid flows on the radial outside of the antenna during use.

Abstract: A replaceable antenna assembly (1) for use with a piston accumulator (2) configured for supplying fluid to a hydraulic cylinder, the antenna assembly (1) comprises; a hollow manifold (3) for flow of fluid, and an antenna (4) connected into or onto the manifold (3) for emitting and receiving electromagnetic waves, wherein the hollow manifold (3) is connectable to and configured to be in fluid communication with both the piston accumulator (2) at one end and a pressure line (5) at the other end, said pressure line (5) being connectable to an external high pressure gas bank, and wherein the antenna assembly (1) further comprises; at least one first bore (6) for transferring signals to and from the antenna (4), and at least two fluid channels (7) symmetrically displaced around the circumference of the antenna, thereby ensuring that most of or all, fluid flows on the radial outside of the antenna (4) during use.

Abstract: A reflector reflects electromagnetic waves, which waves are emitted into a conducting structure from at least one antenna situated at a distance (d?) from the reflector. The distance (d?) is calculated based on measured emitted and reflected waves to and from the reflector, respectively. The reflector includes a reflector disc, an elongated body having a first longitudinal end and a second longitudinal end, the first longitudinal end being fastened to the reflector disc and the second longitudinal end being fastenable to an accumulator piston. Said elongated body further comprises at least two telescopically interconnected reflector tubes rendering reversible adjustment of the elongated body's longitudinal length around a predetermined equilibrium length possible. A piston accumulator applying the reflector, and a method for measuring the distance (d?) are also provided.