Decoherence plate for use in a communications system

A decoherence plate provides reduced field coupling or improved isolation between two or more antennas. An antenna module includes a first antenna, a second antenna and a decoherence plate having a surface. The first antenna transmits one or more electromagnetic signals. The surface of the decoherence plate is positioned in a plane perpendicular to a line connecting the first antenna and the second antenna. For each first path from the first antenna to the plane to the second antenna, in a plurality of paths having a range of path lengths, there is a corresponding second path, from the first antenna to the plane to the second antenna, that is substantially 180° out of phase for a respective wavelength in the one or more electromagnetic signals transmitted by the first antenna. In this way, the decoherence plate reduces the field coupling between the first antenna and the second antenna.