Dual-band Electromagnetic Band-gap Structure And Network Theroy Of Propagation In Multilayered Medium

The unique characteristics of electromagnetic bandgap structures have potentialapplication in microwave region. In this dissertation, dual-band surface wavesuppressoion band-gap structures are realized separately by using cascadedmushroom-like structure with different patch sizes or integrating meandering slots withmushroom-like structure. By inserting the two types of dual-band electromagneticbandgap structures, the backward radiations and the mutual couplings between twoE-plane coupled microstrip antennas is effectively reduced at two operatingfrequencies. With the features of dual-band in-phase reflection phase, dual-bandlow-profile antenna and dual-band radar absorbing material (RAM) based on theMSEBG structure is proposed. The work of the author is mainly focused on:1. In order to analyze the surface-wave suppression bandgap precisely, the infinityboundary of unit cell model is utilized. The dispersion diagram is calculated with thelinked boundary condition by using Ansoft simulation software HFSS (High FrequencyStructure Simulator). The effect configuration parameters of meandering slotted EBGstructure unit (including metal patch width, gap width, permittivity of dielectric board,thickness of dielectric board, metal via radius, slot parameters) on dual-band surfacewave suppression bandgap are studied.2. This paper utilizes a simple locally resonant cavity cell (LRCC) model toprovide an insight into the physical mechanism and the relationship between locallyresonant modes and surface wave suppression bandgaps of the proposed meanderingslotted electromagnetic bandgap (MSEBG) structure. The MSEBG structures have twosurface wave suppression bandgaps which are separately yielded by cross-slots andmeandering slots. It was proved that the cross-slots and the meandering slots producedtwo different groups of MP degenerate modes whose corresponding frequencieslocated within the two surface wave suppression bandgaps.3. Dual-band surface wave suppression band-gap structures are realized by twomethods, one is by using cascaded mushroom-like structure with different patch sizesand the other is by integrating meandering slots with mushroom-like EBG structure.By inserting the two types of dual-band electromagnetic bandgap structures, thecascaded EBG structure and the MSEBG structure can both effectively reduce thebackward radiations around the antenna and mutual couplings between two E-planecoupled microstrip antennas at two operating frequencies simultaneously. 4. The in-phase reflection characteristics of the mushroom-like EBG structurewith symmetric and asymmetric slots are studied, it is shown that the slotted EBGstructure have two in-phase reflection bandgaps. The effect configuration parametersof slotted EBG structure unit (including metal patch width, gap width, permittivity ofdielectric board, thickness of dielectric board, metal via radius, slot parameters) ondual-band in-phase reflection characteristics are studied. Because of the dual-bandin-phase reflection phase bandgap, the MSEBG structure can be used as the ground torealize dual-band low-profile inversed-L antenna. Based on the same properties of theMSEBG structures, dual-band radar absorbing material is proposed. The absorbingperformance is verified by simulations and waveguide measurements using C-bandWR197 and X-band WR90 waveguides. By using the simple waveguide measurementmethod, it is proved that only several units of the MSEBG RAM are required toimplement in this experiment.5. As a basic model, the case that the electromagnetic wave oblique incidence onthe boundary plane between two kinds of medium is considered. By the combination ofelectromagnetic wave propagation and network theory, multilayered media networktheory[C] is proposed innovatively. By using the network theory, the characteristic ofreflection and refraction of electromagnetic wave at the interface between an isotropicregular media and isotropic metametrials, biaxially anisotropic media, the biaxiallyanisotropic media with the angle of the main axis, and uniaxial magnetic anisotropicgyrotropic media is deduced. Thus, the model of electromagnetic wave transmission inmultilayered medium can be converted to the cascaded matrix model with simpleconcept and uniform results.