Investigation On Propagation And Radiation Characteristics Of New Dielectric Waveguiding Structures By Engineerized Electromagnetic Methods

In line with practical needs of development in electromagnetic engineering,in this thesis,we propose various new dielectric waveguiding and leaky-wave antenna structures,the propagation and radiation properties are systematically investigated through engineerized electromagnetic approach characterized by combining the 'field method' with 'circuit method',which mainly involves generalized scattering matrix method,mode-matching method,conservation of complex power technique, transverse resonance technique,improved perturbation method,active transmission line method,and etc.The investigation reveals that these methods are effective, accurate,and flexible,thus can get twice the result with half the effort;the new proposed microwave and millimeter-wave structures including rectangular periodic leaky-wave antennas,modified NRD and groove guide structures,as well as the equivalent ENZ rectangular and circular channel waveguides,exhibit unique electromagnetic phenomena.For example,the radiation of inverted rectangular dielectric grating antenna enhances greatly compared with the traditional grating structure,the metallic grating antenna with LHM substrate supports simultaneously two radiation beams,and ultra-narrow ENZ channel possesses supercouplering ability, which illuminate that they are of promising applications in microwave and millimeter-wave engineering.For instance,they can be used to develop and design small size leaky-wave antenna with high efficiency,double-beam radiation antenna, intense field cavity and measuring system for dielectric constant of material.Lastly, the issue of complex mode which exists in the LHM waveguide structures everywhere is carefully discussed.We indicate that complex mode is the constituent part of complete eigen mode set in the LHM structures,and great attention should be paid to its effect when carrying on correlative calculations to guarantee the accuracy of the numerical results,this is of theoretically significant for the investigation on propagation characteristics of LHM waveguides.