Analysis of Asymmetrically Corrugated Goubau-Line Antenna for Endfire Radiation

We systematically analyze and describe a new type of traveling-wave endfire antenna based on an asymmetrically corrugated Goubau line that exhibits high efficiency and has a low profile. By proving that asymmetry is a necessary condition in addition to the Hanson-Woodyard condition for traveling-wave endfire radiation, we study the effect of asymmetric corrugation on the mode guide and coupling. We subsequently show that two different waves are independently guided along the two corrugated edges, whose phase difference leads to a transversally polarized dipole moment radiating in the endfire direction. A closed-form expression for the radiation pattern is derived based on the proposed analysis to approximately predict the antennas' optimum length. To verify the proposed analysis and design principles, results from an experimental prototype operating at 13-15 GHz are also provided. The experimental results show that the antenna design has an average gain of 9.9 dBi and an average efficiency of 82%. The agreement between the predicted results and the final optimized results validates the proposed analysis.