UHF radio propagation characteristics in straight open-groove structures

The imperfect waveguide method is used to study UHF radio propagation characteristics in open-groove structures with particular interest being devoted to the frequency characteristics of the propagation attenuation constant. Attenuation of propagation has been characterized by the surrounding media absorption, the roughness of the sidewall, and the sidewall tilt. Our study shows that attenuation due to the surrounding media absorption is inversely proportional to the square of the frequency, whereas that due to the roughness on the sidewall surfaces is inversely proportional to the frequency and that due to the sidewall tilt is directly proportional to the frequency. The imperfectness of the actual open groove structures will cause additional electromagnetic mode conversion, thus increasing the propagation loss. The theoretical results are in agreement with the experimental data.