Study On Sine Waveguide And Its Applications

The spectrum development of millimeter wave and terahertz band is a hot spotsubject in modern electronics field. It has great value in military equipment, scientificresearch, national economy and other fields. Vacuum electronic technology as animportant technical method is being used to develop much-needed high powerelectromagnetic radiation sources. Traveling wave tube and backward wave oscillatorare two widely applied high power radiation sources. With the increasing of operatingfrequency, the slow-wave structure as the core component of the device is encounteringtwo scientific challenges about high transmission loss and strong reflection. In seekingsolving solutions, a novel type of electromagnetic structure which is called sinewaveguide is put forword. And it is speculated that the sine waveguide has good radiofrequency transmission characteristics. Therefore, the sine waveguide, as a slow-wavestructure, is able to significantly improve device performance of the existing radiationsources. At the same time, it also has important application merit in designing passiveelectromagnetic devices.This thesis does a detailed analysis for the sine waveguide on three aspects,including slow wave characteristics, radio frequency transmission characteristics andbeam wave interaction characteristics. And it is pointed out that the sine waveguide canbe applied in design a millimeter wave and terahertz transmission bandpass filter,transmission line and slow wave structure in traveling wave tube or backward waveoscillator.The innovations of this thesis are mainly concluded as follows:1. Proposed a novel type of electromagnetic structure: sine waveguide. It possesseswide bandwidth, low transmission loss, low reflection and easy fabricationcharacteristics. Therefore, it can be considered as a slow wave structure in millimeterwave and terahertz regime.2. Theoretically indicated and experimentally verified that the sine waveguide canbe considered as a millimeter-wave and terahertz transmission line. The experimentalresults of a W-band sine waveguide transmission line show that, its transmission loss is about0.048dB/cm in the entire frequency band, which is equivalent to that of standardrectangular waveguide.3. Proposed a design scheme of the220GHz sheet beam sine waveguide travelingwave tube with a peak power of150W. The scheme has a gain of over34.7dB and anelectronic efficiency of over4.8%in the frequency range of200～240GHz under abeam voltage of20.8kV and a beam current of150mA. And the maximum peak poweris270W. At the same time, a design scheme of the W-band traveling wave tube with apeak power of1kW is put forward. A novel attenuator and an input or output structurecompatible with the device. Thus, it can deliver1kW peak power output in the entirefrequency range of90～98GHz by tuning the input signal between30mW and490mW under a beam voltage of21.1kV and a beam current of400mA.4. Proposed a design scheme of the220GHz pencil beam sine waveguide backwardwave oscillator with a watt-class peak power. The oscillator can deliver over2W peakpower output in the frequency range of210～230GHz by tuning the beam voltage from17kV to26kV under a beam current of10mA. At the same time, a design scheme of awatt-class1THz sheet beam sine waveguide backward wave oscillator is put forward. Itcan deliver1W peak power output at995.6GHz under a beam voltage of19.4kV and abeam current of5mA. In addition, in order to extract power easily, a rectangularwaveguide grating is considered as a reflector for terahertz backward wave oscillator.5. Constructed the basical theory about the dispersion characteristics and the smallsignal gain of the sine waveguide. The "cold" and "hot" dispersion equations are gainedfrom Maxwell equations by field theory. Afterwards, the numerical computation methodis used to solve those equations, and then compared with the results from softwaresimulation method for verificating our theory.In summary, the investigation of the novel sine waveguide and its applicationanalysis will favor the development of the millimeter wave engineering and terahertztechnology, especially as a novel way for study on high power millimeter wave andterahertz electromagnetic radiation sources.