Far Field Computation of the Traveling Wave Structures and a New Approach for Suppressing the Sidelobe Levels

The effective radiation section (ERS) proposed for studying the radiation of traveling-wave structure is further studied in this communication. The formulas for computing the radiation pattern of traveling-wave structure using the newly defined ERSs is derived. The effect of the attenuation constant on the computation of radiation pattern is discussed. A new idea for reducing the sidelobe level (SLL) of the traveling-wave structure is proposed by suppressing the emissions from the corresponding ERSs. It is found that the ERSs are not always located at the ends of the traveling-wave structure, this is quite different from the conventional viewpoint concerning the fast-and slow-wave radiations, and the reason is explained in detail. A line-source model corresponding to a 70-cell composite right/left handed (CRLH) traveling-wave structure is employed in the analysis, and the results are verified by full-wave method.