Novel folded SRR-loaded waveguide bandpass filters

A novel class of E-Plane, low-cost, compact and metamaterial-based filter structure using FSRRs for microwave, millimeter wave applications has been proposed. The proposed FSRR-loaded waveguide bandpass filter has been designed and simulated at 9.45 GHz. The structure can be easily realized with a single metal insert within a rectangular waveguide. This kind of filter can be found in applications particularly in the mm-wave range circuits, e.g. in diplexers and multiplexers

Novel SRR loaded waveguide bandstop filters

Two types of novel split ring resonator (SRR) loaded rectangular waveguide bandstop filter structures have been presented. The first proposed SRR-loaded waveguide bandstop filter has been designed simulated and tested. Using the combination of the split ring resonators, conductive wireline and transversely placed metal septa, the composite material has been built and inserted into the hollow rectangular waveguide to form an SRR-loaded waveguide unit. The bandstop filter has been constructed by cascade of the two resonator unit cells. The second proposed multilayer SRR loaded waveguide bandstop filter has been designed and simulated. Three transverse periodic SRRs are present on either side of the dielectric blocks

Size reduction of microstrip antennas using left-handed materials realized by complementary split-ring resonators

Recently, metamaterials (MTMs) engineered to have negative values of permittivity and permeability, resulting in a left-handed system, have provided a new frontier for microwave circuits and antennas with possibilities to overcome limitations of the right-handed system. Microwave circuit components such as waveguides, couplers, power dividers and filters, constructed on left-handed materials, have demonstrated properties of backward coupling, phase compensation, reduced sizes, and propagation of evanescent modes. However, there is very limited work to date, on the microstrip antennas with metamaterials. Microstrip antenna is widely used for its low-profile, simplicity of feed and compatibility with planar microstrip circuitry. As the trend towards miniaturization of electronic circuitry continues, antennas remain as the bulkiest part of wireless devices. There are three primary objectives to the present work: 1. Explore the possibility of miniaturizing microstrip patch antennas using left-handed materials through phase-compensation 2. Achieve negative permittivity using Complementary Split-Ring Resonators (CSRR) 3. Implement CSRR in the ground plane of a rectangular patch antenna, and validate through simulation and measurement A rectangular patch antenna with a combined DPS-DNG substrate has been analyzed with the cavity model, from which the condition for mode propagation has been derived. Criteria for ‘electrically small’ patch, using phase-compensation have been developed and propagating modes that satisfy these criteria have been obtained. With an objective to design practically realizable antennas, amongst several available LHM structures, the Complementary Split Ring Resonators (CSRR) has been chosen, primarily for the ease of implementation in the ground plane. CSRRs are periodic structures which alter the bulk effective permittivity of a host medium in which they are embedded. The effective permittivity becomes negative in a certain frequency band defined as a ‘stop-band’. In the present work the frequency response of the CSRR and the ‘stop-band’ has been determined using a full wave solver, from which, effective permittivity of the composite with CSRRs has been obtained by parameter extraction. Finally, several combinations of patch and CSRR in the ground plane have been designed and constructed in the X-band frequency range. Measurements of input characteristics and directivity have been validated through simulation by Ansoft Designer and HFSS. It has been observed that the best designs are achieved when the ‘stop-band’ of the CSRR corresponds to the desired resonant frequency of the antenna. Under these conditions, a size reduction of up to fifty percent has been achieved and it is noted that the back lobe is negligible and the directivity is comparable to that of a right-handed microstrip antenna

Wave Interaction With Epsilon-znd-Mu-Near-Zero (emnz) Platforms and Nonreciprocal Metastructures

The concept of metamaterials has offered platforms for unconventional tailoring and manipulation of the light-matter interaction. In this dissertation, we explore several concepts and designs within this scope. We investigate some of the electromagnetic characteristics of the concept of “static optics”, i.e., wave interaction with structures in which both the relative effective permittivity and permeability attain near-zero values at a given operating frequency and thus the spatial distributions of the electric and magnetic fields exhibit curl-free features, while the fields are temporally dynamic. Using such structures, one might in principle ‘open up’ and ‘stretch’ the space, and have regions behaving electromagnetically as ‘single points’ despite being electrically large. We study some of the wave-matter interaction in these platforms and suggest possible designs for implementation of such structures in different frequency regimes and experimentally verify our findings in the microwave regime. Another research direction that is explored in this dissertation is the development of some nonreciprocal metaplatforms. We investigate theoretically an approach through which one-way electromagnetic wave flow can be achieved using properly designed nonlinearity combined with structural asymmetry. The approach is rather general and applicable for any desired frequency regime and opens doors for high performance “electromagnetic diodes” and nonreciprocal metasurfaces and metastructures. We also theoretically study the usage of time-dependent materials in achieving wave flow isolation within plasmonic waveguides environments. We also provide physical remarks on our various findings

Metamaterial

In-depth analysis of the theory, properties and description of the most potential technological applications of metamaterials for the realization of novel devices such as subwavelength lenses, invisibility cloaks, dipole and reflector antennas, high frequency telecommunications, new designs of bandpass filters, absorbers and concentrators of EM waves etc. In order to create a new devices it is necessary to know the main electrodynamical characteristics of metamaterial structures on the basis of which the device is supposed to be created. The electromagnetic wave scattering surfaces built with metamaterials are primarily based on the ability of metamaterials to control the surrounded electromagnetic fields by varying their permeability and permittivity characteristics. The book covers some solutions for microwave wavelength scales as well as exploitation of nanoscale EM wavelength such as visible specter using recent advances of nanotechnology, for instance in the field of nanowires, nanopolymers, carbon nanotubes and graphene. Metamaterial is suitable for scholars from extremely large scientific domain and therefore given to engineers, scientists, graduates and other interested professionals from photonics to nanoscience and from material science to antenna engineering as a comprehensive reference on this artificial materials of tomorrow

Artificial engineered materials for novel accelerator applications

This thesis presents the design of a metamaterial loaded waveguide for accelerator applications, the metamaterial comprises of sheets of Complementary Split Ring Resonators (CSRRs). These CSRRs act as a left handed medium at certain frequencies allowing the structure to be used for the generation of reverse Cherenkov radiation. The proposed initial design exhibits a left handed TM31-like mode at 5.5 GHz with a R/Q of 6.6 kΩ/m and a shunt impedance of 10.9 MΩ/m, indicating strong beam coupling, this is verified by the strong longitudinal wake impedance of 13 kΩ. Design considerations are discussed to alleviate typical issues of metamaterials in high-power environments and make the structure more suitable for a proof-of-concept beam test at the Cockcroft Institute. The objectives of this study have been to increase fabrication suitability, reduce the number of hybrid modes and improve resistance to damage from high power, while maintaining the electromagnetic performance. Designs with increased sheet thickness, ring spacing and curvature are discussed via electromagnetic and wakefield analysis. The final chosen design with 1mm thick metasurfaces exhibits a suitable TM31-like mode at 5.86 GHz. This mode exhibits a R/Q of 4.5 kΩ/m, a shunt impedance of 22.6 MΩ/m and a longitudinal wake impedance of 10.6 kΩ, indicating that the modified geometry does not significantly affect the electromagnetic interaction of the structure with charged particles. To understand the wave-beam interactions in the structure, particle in cell simulations were performed for a commercial beam, a very high intensity beam and the current beam available on the Versatile Electron Linear Accelerator (VELA) which the structure is designed for. Through these studies the VELA beam is confirmed as the most suitable for reverse Cherenkov applications. The CSRR loaded structure can lead to novel designs of particle detectors, coherent sources and acceleration schemes, leading to compact novel accelerator applications