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An improved fast shadowing technique fit for the calculation of electromagnetic field is proposed in this paper based on the shadowing technique of z-buffer in computer graphics. The traditional shadowing algorithm consumes too much time, for it is necessary to judge the shadowing relationship of every two facets. The proposed algorithm combining z-buffer with traditional algorithm falls into the shadowing processing using triangle facet modeling. The problem of great time consumption in shadowing judgment for electrically large targets is well solved through proper subdivision of buffer and localization of judgment within facets in the surrounding buffer elements. The proposed arithmetic has great advantages over the traditional one, especially in its high running speed. This improved technique is tested to be valid in that it remarkably increases the computation speed on the premise of satisfying the precision requirement.

In part I of the present paper, we analysed helical slow-wave structures of travelling-wave tubes (TWTs) taking into account the space harmonic effects arising from the axial periodicity of helix turns as well as azimuthal periodicity of the dielectric helix-supports and metal vanes of the envelope of the structure. Here, in part II of the paper, we extended the analysis to the fast-wave regime to study a disc-loaded circular waveguide interaction structure of a gyro-TWT taking into account the space harmonic effects arising from the axial periodicity of the annular discs. Four variants of the structure were studied. Two of these variants use thin and thick metal discs, respectively. The third variant has inherently two interwoven metal disc-loaded structures, and the fourth variant has dielectric discs interposed between consecutive metal discs. We studied the effect of tapering the disc parameters and predicted the optimized parameters for the wideband and high-gain gyro-TWT performance. The ana...

Microwave power transmission (MPT) has many advantages. However, previous studies have indicated that MPT interferes with wireless data communication. In this paper, an adaptive polarization switch...

For a base station antenna in 5G mobile communications, lens antennas have been proposed for excellent multiple beam performances. In this paper, the negative refractive index (NRI) lens is selecte...

This paper proposes a multi-beam search method based on an active phased array antenna system using digital beamforming. It includes initial beamforming, valid beam selection, and beam angle estima...

In this paper, a polarization conversion metasurface is proposed, which can realized ultra-wideband circular polarization (CP) maintaining reflection in the frequency range 7.3–28.7 GHz; in additio...

In this paper, a development of low cost, miniature, highly integration broadband RF transceiver front-end using the high selectivity hybrid resonator RF bandpass filters, and diplexer integrated w...

In this paper, a compact triple-band printed monopole antenna with circular polarization (CP) has been presented for C-band wireless applications. To achieve the triple-band CP response, the top la...

In this paper, tunable and efficient absorbers are proposed based on graphene–metal nano structures. The designed structures are consisted of multi layers of graphene (ring- and plate-shaped) and g...

Aiming at the problems of low-frequency coverage, angle and polarization instability of ultra-wideband (UWB) frequency selective surface (FSS) in practical application, this paper introduces the ad...

In this paper, we have presented the influence of surface traps/states on RF and microwave performance of fully recessed Schottky anode AlGaN/GaN lateral Schottky barrier diode (L-SBD) using numeri...

International audience; Metal additive manufacturing processes, such as laser beam melting (LBM), can play a key role in developing antenna-feed chains because monolithic and multifunctional parts can be manufactured with high geometric freedom in the design phase. Using LBM technology, lighter and more compact antennas can be produced and manufac-turing costs can be reduced. However, the surface roughness of internal surfaces in waveguides produced by LBM is much higher (about 10 μm Ra) than that produced by conventional manufacturing tech-nologies. Consequently, such high surface roughness of the internal surface can affect electrical current propagation through the waveguide and corresponding transmitted power. In this paper, abrasive flow machining (AFM) was used to reduce the surface roughness of the internal surfaces of four different waveguides used at both K and Q bands. A significant reduction in the transmission loss at both K and Q bands was observed as their internal surface rough-ness decreased from about 10 μmto1μm Ra. This was assumed to be due to an increase of the internal surface electrical conductivity with the decrease of roughness in waveguides channels.

In this paper, the RF behavior of a 35 GHz, TE04 mode cylindrical cavity gyrotron is investigated using the nonlinear multimode theory and PIC code “CST Particle Studio”. A code is developed to rea...

In this paper, pixelated Frequency Selective Surface (FSS) layer embedded in two carbonyl iron-filled silicon rubber (CISR) sheets are used for design of broadband microwave absorber in frequency r...

This paper presents the results of theoretical and experimental studies of electromagnetic waves backscattering by partially non-reciprocal media. It is proposed to implement a controlled reflector...

This paper presents the design and simulation of a novel TE10 to TE30 mode converter operating at 3.7 GHz and is subjected to high RF power of 500 kW in Continuous Wave (CW) regime. The design inco...

This paper proposes a low-profile, low-cost, and wideband quad-layer element for designing transmitarray antenna (TA). Changing the dimensions of the element shifts its passband. Sometimes, this sh...

A wideband antenna pair used for 5G mobile phones is proposed in this paper. Both elements of the antenna pair consisting of an open slot and a coupled feeding line can cover the band of 3.3–6 GHz,...

In this paper, a novel method to decrease the sidelobe level (SLL) of conformal leaky-wave antennas (CLWAs) which are synthesized based on the holographic techniques is proposed. For this purpose, ...

Various decoupling methods were proposed and investigated for multiple-input multiple-output (MIMO) Base Station (BS) systems. These methods can effectively decouple the dual-polarized co-polar signal but fail to decouple the cross-polarized signal, similarly limiting the BS's overall decoupling performance. In this paper, different antenna arrays are designed to illustrate the coupling mechanism of cross-polarized BS antennas, and a comprehensive study of the relationship between antenna configurations and mutual couplings is conducted. It is shown that compact size antenna elements enlarge the edge-to-edge separation, and the loop-shaped dipole elements reduce the cross-polarization couplings. Finally, the array-antenna decoupling surface (ADS) method is applied in a 2×2 array composed of the designed antennas. Thanks to the improved antenna unit, the decoupling task is eased, and a better decoupling performance is achieved compared with the original ADS work.

In this paper, a dual-band power amplifier based on tri-band impedance matching circuit is proposed. This amplifier uses reverse thinking to combine the tri-band impedance matching network with the...

This paper presents the unique structure of a hybrid antenna with a blend of Peano–Gosper, Koch and Minkowski curves using a modified partial ground plane for multi-standard wireless applications. ...

To improve the detection capability of laser fuze, this paper researches the laser echo signal detection method and echo power calculation method on laser fuze. From the multi-attitude intersection...

In this paper, a low-profile quad-band frequency selective surface (FSS), designed as a sub-reflector for satellite communication is presented. This single layered FSS employs non-concentric open l...

In this paper, a novel metasurface-based Fabry–Perot Cavity antenna is presented. The antenna is wideband, directive and has a high front-to-back ratio. The idea of the antenna is based on loading ...

In this paper, the design of an interaction cavity for a very high-power W-band gyrotron is proposed for the generation of megawatt range of power. The proposed gyrotron is designed to generate 1.5...

Wireless underground sensor network (WUSN) is widely used in agriculture, frontier defense, and other fields with great research value. This paper takes the propagation characteristics of the elect...

This paper presents a ‘reconfigurable narrow open-slot LTE MIMO antennas for metal-rimmed smartphone applications,’ which consist of two structurally identical L-shaped slot antennas combined with ...

The present paper deals with an approach to investigate the rectangular waveguide (RWG) using the conformal mapping technique, where the rectangular shape is converted to a sectoral one for the the...

In this paper, a high Q-factor-based defective ground structure (DGS) etched microwave resonator is demonstrated to identify the unknown thickness of non-destructive monolayer dielectric material. ...

This paper proposes a DTV/LTE antenna design without physical structure for laptop computers. By changing the laptop’s right revolving axis to a non-conductor material and exciting several dipoles ...

This paper describes a new design strategy which is used to obtain a fivefold increase in the 3 dB axial ratio bandwidth of linear to circular polarization convertors based on anisotropic frequency selective surfaces composed of single screens of cross slots. The performance improvement is obtained by employing stratified dielectric media to carefully tailor the shape of the TE and TM spectral transmission responses. We demonstrate that a bandwidth of 24.5% can be achieved at a center operating frequency of 10.6 GHz using an array of unequal length cross-slots embedded centrally between two 2.25 mm thick dielectric slabs (εr = 9.0). Moreover it is shown that the inherent self-filtering behavior of the structure provides greater rejection of unwanted signals than designs embedded in lower permittivity material. Computed and experimental axial ratio results are compared to verify the new design methodology

In this paper, the arc array for squint-less near-field focusing is used, theoretically analyzed, and verified. The arc array is designed to overcome the squint phenomenon in the near-field and tra...

In this paper, a novel design of a diplexer for mobile communication base station is proposed, theoretically investigated and successfully tested. The proposed design of the diplexer is implemented...

In a recently published paper, Chetan Barde et al. [Barde C, Choubey A, Sinha R. A set square design metamaterial absorber for X-band applications. J Electromagn Waves Appl. 2019:1–14.] have propos...

In this paper, a dual annular ring patch antenna with high isolation for Multiple Input Multiple Output (MIMO) Satellite application at 4 GHz is presented. The mutual coupling reduction and circula...

In this paper, a microstrip low-pass filter (LPF) using folded-flag-shaped resonators is designed and presented. Its base resonator length is 12.4 mm, and the proposed low-pass filter has a sharpne...

This paper conceptualizes the development of a frequency selective surface (FSS) with 3-D unit cells. The FSS unit cells individually present a three-dimensional structure, whereas collectively the...

In this paper, a compact substrate integrated waveguide (SIW) based dual-band filter which utilizes the dual resonance provided by asymmetric double-ring D-shaped resonators that are incorporated o...

In this paper, the physical model is extended for vias embedded in layered media between two parallel-plate pairs. The effect of this inhomogeneity on signal integrity analysis is crucial, but is rarely studied especially by using the equivalent circuit model. The model presented in this paper is constituted by upper and lower via-to-plane capacitances which are different from each other due to the inhomogeneous dielectrics and equivalent impedance matrix of the parallel-plate cavity with equivalent wave number. The via-to-plate capacitance with layered media is calculated by using cascaded Green’s function with image theory and integral equation method based on partial capacitance, which is the main contribution in this paper. The parallel-plate impedance is calculated by using the cavity resonator method. Transverse resonance method as well as an equivalent approximation method is used for wave number evaluation. For the first time, the circuit model presented in this paper is used for the issue of laye...

In this paper, a new approach for electromagnetic modeling of the diffraction of finite multi-dielectric thickness in metallic wave-guides is presented. The proposed model, based on the method of moments combined to the generalized equivalent circuit, can concern several applications such as the investigation of vegetation leaves properties. Hence, in this work, we are interested in studying a corn leaf which is assumed as a superposition of rectangular dielectric slabs. We develop an electromagnetic analysis of a rectangular wave-guide loaded with a dielectric model that is composed of a leaf plant with a finite thickness. Interest has been focused on the influence of the wave diffraction according to the geometrical intern of the corn leaves. In this paper, we are particularly interested in studying these parameters against the dielectrics widths and the distances separating them. To validate this work, the obtained results are compared with those previously measured and published. A good agreement with...

A planar sensor designed using the fourth Hilbert fractal curve iteration for solid material characterization at multiple frequencies is reported in this paper. The fractal curve is self-similar with space filling properties. The Hilbert fractal geometry is used to form a compact resonator, with a multiband frequency response where miniaturization is achieved, since a large transmission line length is effectively confined in a limited area. The sensor provides five resonances in the frequency range from 0 to 5 GHz. The resonant frequencies are 0.56, 1.68, 2.72, 3.69 and 4.72 GHz, all used to measure the real permittivity of known samples with a sensitivity of 7, 20, 27, 43 and 50 MHz/permittivity, respectively. The sensor is used to measure dielectric samples with 20 x 20 mm2 areas with several thicknesses. Simulations and measurements demonstrate that the Hilbert fractal geometry can be used to design a multiband planar sensor for solid dielectric material characterization.

In this paper, the design of an interaction structure for a 10-kW, W-band gyrotron is presented. The beam voltage and beam current are chosen as 30 kV and 1 A, respectively. The mode of interaction...

In this paper, we present the compact bandpass cavity filters for UHF range. We investigate the properties of coaxial resonators with various numbers of tubular posts from one to four. We show that...

This paper presents a design investigation of the Electron Optical Gun (EOG) for a 42 GHz, 200 kW second harmonic gyrotron operating in the TE0, 3 mode. The initial design of MIG is done using esta...

This paper presents a robust optimization method to design patch antennas that consider uncertainties from the substrate electromagnetic properties and the manufacturing equipment. The robust optim...

In the paper, the design and simulation of the TEM-TE10 wideband and high-power mode converter (MC) are investigated. The working frequency of the MC is in the frequency range of 4.3–8.8 GHz (68.7%...

In this paper, a novel miniaturized triple-band planar monopole antenna combing single-cell metamaterial structure and defected ground plane is proposed. The miniaturization and triple-band charact...

An asymmetric coplanar waveguide fed frequency reconfigurable antenna based on composite right/left-handed transmission line is presented in this paper. The antenna is a composite right/left-handed...

In this paper, an assembly of substrate mediated graphene-coated cylindrical nano-rods is proposed as an efficient broadband absorber. Initially, a square lattice of isolated graphene-based particl...