A Compact Single Conductor Transmission Line Launcher for Telemetry in Borehole Drilling

A very compact and conformal launcher for single conductor transmission lines (SCTLs) at the HF-band is presented. Also the concept of using drill pipes as the conductor of SCTL is introduced for the first time to satisfy the need for cost-effective and real-time data communication in drilling process. It is shown that a TM surface wave can be launched effectively making use of the drilling mud around the drill pipe. Provision of TM surface wave launchers that can fit within the borehole at both ends makes it feasible to transmit data over the drill pipe from downhole to the surface and vice versa. The launcher is composed of an open ended helical conductor which concentrically surrounds the drill pipe with appropriate pitch and length forming a compact surface wave launcher. Keeping its dimension smaller than 0.005 lambda x0.005 lambda x0.03 lambda, the proposed launcher provides 2% fractional bandwidth at low HF-band.