A communication module for a survey tool assembly comprising: an outer housing, an inner body within the outer housing, an RF transceiver in the inner body, at least one coupling for coupling the communication module to a survey tool assembly, wherein the inner body comprises two or more apertures circumferentially arranged about the inner body, each aperture having: a) a length that allows propagation of RF signals to/from the RF transceiver, and b) a width such that the body has structural integrity to withstand: torsional forces due to rotation of a survey tool assembly and/or axial forces due to forces along the survey tool assembly.