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Surface waveguides (SWGs) are a class of open-boundary structures with the capability of guiding surface waves which are intimately bound to the surface of the structure. One of the most commonly occurring type is the planar structures consisting of periodic subwavelength elements. Due to the capability of controlling the propagation path of surface waves (SWs), SWGs have been employed for the applications...
In this paper, the design and particle simulation of a Ka-band stagger tuned gyro-twystron amplifier is presented. The concept of stagger tuning in gyro-twystron improves the bandwidth along with high RF output power which is suitable for radar application. The complete amplifier structure is modelled in “CST particle studio” for studying the beam wave interaction behaviour. The PIC simulation predicted...
In terms of seeking the characteristics of wave propagation many engineering infrastructures can be regarded as a waveguide due to their distinguished physical properties in contrast with the natural surroundings. Coastal protection dykes can be treated as such a waveguide. Taking this as the conceptual model we try to seek the signature of the voids or defect weak spots inside the dyke or in the...
Triple-mode and quadruple-mode bandpass filters using triangular half-mode substrate integrated waveguide (HMSIW) are presented. To realize the two multi-mode filters, the triangular HMSIW cavity is perturbed by introducing via-hole arrays at different positions of the structure. The perturbation causes mode shifting of certain resonant modes near to the other resonant modes which are not affected...
Photonic crystal (PhC) structures are good platform for solid-state quantum photonics. Efficient generation and guiding of single photons from semiconductor quantum dots (QDs) embedded in two dimensional (2D) PhC waveguides have been demonstrated recently. Various cavity quantum electrodynamics (CQED) phenomena have also been intensively explored in 2D PhC nanocavities coupled with a single QD. On...
We analyse and compare the effects of the spatial dispersion and structural anisotropy on the spectrum of a metamaterial slab. Dielectric function of the slab we describe within Drude-Lorentz approximation. Anisotropy is of the slab is introduced through the anisotropy of plasma frequencies corresponding to the different component of the permittivity tensor. Spatial dispersion is considered within...
In this paper, a new method of designing dual frequency beam reconfiguration reflectarray antenna is proposed. The dual resonant reflection unit cell which is composed of double dipole patch printed on grounded dielectric substrate is implemented to construct the reflectarray. And a slotted waveguide arrays is utilized to be the feed of the antenna, it provides an approximate cylindrical wave in its...
An efficiency-improved high power virtual cathode oscillator with coaxial waveguide is presented. The virtual cathode oscillation is axially excited by low magnetic field guiding annular electron beam. Electron beam pre-modulation, microwave feedback structure and coaxial diode are employed to increase the device efficiency. In S-band, this device radiates 2.4GW microwave power and over 21% efficiency...
The goal of this paper is to study the electrostatic field due to an arbitrary charge distribution on a dielectric layer in a dielectric-loaded rectangular waveguide. In order to obtain this electrostatic field, the potential due to a point charge on the dielectric layer is solved in advance. The high computational complexity of this problem requires the use of different numerical integration techniques...
The main goal of this work is the review of the recent advances in the study of the multipactor RF breakdown phenomenon in RF satellite microwave passive devices for space telecommunication applications developed in the Val Space Consortium. In this work several topics related with the multipactor phenomenon will be discussed.
According to Babinet's principle a square complementary asymmetric split ring resonator (caSRR) is proposed. Interestingly, due to the particularity of the caSRR structure, it can be fabricated on a mental sheet without the substrate, which is named as Stereo-caSRR. A microwave sensor which consists of a rectangular waveguide loaded with the square stereo-caSRR is designed. Simulation results show...
Dispersion forces such as Casimir, Casimir-Polder and van der Waals forces arise due to fluctuations of the quantised electromagnetic field. Any alteration of the environment in which the (virtual) photons propagate leads invariably to a modification of the respective interaction. Waveguide structures in particular are known to resonantly enhance Casimir-Polder interactions [1]. Here we focus on the...
Metasurfaces, which are quasi-two-dimensional (quasi-2D) textured surfaces comprised of a periodic or aperiodic array of sub-wavelength building blocks, provide a fully-planarized platform for controlling the propagation, radiation, and scattering of electromagnetic waves. Compared to their three-dimensional (3D) metamaterial counterparts, 2D metasurfaces offer several advantages including lower losses,...
Metasurfaces, also known as metafilms, have recently been developed by researchers for various applications that exploit their exotic electromagnetic characteristics which cannot be found in nature. These applications include compact filter designs, electromagnetic cloaking and illusion coatings, miniaturized waveguides, and many new types of antennas with enhanced functionalities. Specifically, metasurfaces...
This paper proposes the design of weather radar antenna on X-Band frequency with two polarizations. The antenna is built based on slotted waveguide antenna array (SWAA) with its antenna structure consists of 2 layers, first layer is a radiating waveguide and second layer is a feeder waveguide. The first layer is composed of 5 waveguides in which each of waveguide consist of 64 slots, while the second...
In the development of cellular communication systems, the demand of higher data rate and larger channel capacity leads to explore millimeter-wave (mm-wave) band. The mm-wave band (from 10 GHz to 200 GHz) is seen as the prior candidate of the carrier frequency for fifth generation (5G) mobile network, since almost all the frequencies below 10 GHz are occupied.
This paper presents a kind of circular loop antenna (CLA) constructed by coaxial waveguide, which is able to generate radio beams carrying orbital angular momentum (OAM) under the condition of dual port excited. The proposed CLA can reconfigure OAM modes with opposite sign by retrieving the alternative ports. Method induced in this work to design CLA based OAM generator could be extended to other...
Nonlinear Cherenkov radiations (NCR) have attracted increasing research interest in the past years. Similar to the traditional Cherenkov radiation effect in particle physics, NCR requires that the nonlinear polarization wave propagates faster than the harmonic waves. Cherenkov frequency up-conversions can be automatically realized in normal dispersion materials and extensive work on Cherenkov second-harmonic...
We report terahertz sensing applications of photonic crystal cavity with a high quality factor (∼9300). The frequency response of the cavity was measured using a compact terahertz source based on a resonant tunneling diode (RTD), and the results were compared with the results obtained using a bulky, precise frequency multiplier. The oscillation frequency of the RTD was tuned by changing the applied...
Frequency selective surface (FSS) is periodically patterned metal patches or complementary apertures etched on metal sheet, which spatially filters the incident electromagnetic waves. Recently, vast research interest has been drawn to the reconfigurability of FSS, where lumped elements are integrated to dynamically control the bandpass/bandstop response. While loaded with PIN diodes or varactors,...
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