Millimeter Wave Band, Flat Rectangular Grating Radiation Characteristics

Smith-Purcell devices and Cherenkov devices are promising candidates as sources of high-power millimeter wave band radiation, which are important directions of high-power microwave (HPM) technology and are focused by all the researchers in the world today. This dissertation gives theoretical analysis, PIC simulation on the high-power millimeter wave band Smith-Purcell devices and Cherenkov devices.This dissertation mainly focuses on Smith-Purcell and Cherenkov efforts for periodic millimeter grating with rectangular profile. The research concludes two different kinds of models: a sheet beam passing through a millimeter grating with cover board or without cover board. The main job is as following:1. Mode-matching method is used to get the'cold'and'hot'dispersion relation of grating, and then the parameters of grating and beam are changed separately to see how can these parameters influence the dispersion and gain of grating. Finally, the results which get from the gratings with cover board and without cover board are compared in detail.2. Secondly, PIC methods are used to study the evanescent and the harmonious electromagnetic waves above the grating without cover board, the bunching of the beam and the characteristics of current have been studied too. From the study, such following conclusions can be gotten: First, Slow electromagnetic wave in the proximity of the grating leads to the bunching of the beam. Second, Slow electromagnetic wave is the evanescent wave while the harmonious electromagnetic waves are the radiate wave. Third, The radiate characteristics of harmonious electromagnetic waves are in agreement with Brau's predictions. Last, Some of the evanescent wave is diffracted away from the surface and become radiate wave at the ends of the grating.3. After that, PIC methods is applied to study the evanescent electromagnetic and the harmonious waves above the grating with cover board, the output power at the end of this kind of grating is also been studied in different height of cover board. Some comparison and analysis from the gratings without cover board and with cover board are given in this paper. At last, Our study shows that the output power and the work frequency can be changed by changing the high of cover board.4. Furthermore, The paper uses PIC methods to study the effects of hollow structure and reflector to the output power of the grating with cover board, and our study shows that the effects of hollow structure and reflector are depended on the height of the cover board and the output power can be improved efficiently by choosing right hollow structure and reflector.