Advanced Electromagnetics

High-Frequency Electrodynamics of Slow Moving Media Taking into Account the Specular Reflection

N. N. Grinchik, O. V. Boiprav — Sat, 06 Feb 2021 00:00:00 +0100

The paper presents the results of constructing the physical and mathematical model of high-frequency electromagnetic waves propagation in slowly moving media of finite dimensions, which takes into account the phenomena of specular reflection of these waves. The constructed model is based on formulas designed to determine the speed of electromagnetic waves propagation in slowly moving media of finite dimensions, as well as on equations designed to describe these waves. The advantageous feature of these equations is that they take into account the Fresnel drag coefficient for electromagnetic waves propagation speed. The approach to solving of these equations, as well as the approach to modeling of the process of electromagnetic waves propagation in slowly moving media of finite dimensions, based on the use of a difference scheme, in which the motion of these media is taken into account, is proposed. It has been determined that the proposed model and approaches can be used in solving problems related to the construction of receiving-transmitting paths, as well as in solving problems of aeroacoustics.

Toward Wideband Frequency Rejection: An Efficient Frequency Selective Scheme

W. Nadjari, J. Nourinia, Ch. Ghobadi, M. Majidzadeh — Thu, 01 Apr 2021 00:00:00 +0200

This paper outlines a Frequency Selective Surface configuration designed for wideband filtering characteristics. The proposed design topology includes two-layer conductive elements printed on an FR4 substrate with a thickness of 1.6 mm. On the front side, a square loop and four branches are placed, and on the other side of the substrate, there is another square loop supported by two modified vertical arms. The use of square loops as one of the trendy elements in frequency selective designs provides the opportunity to tune the resonances and obtain the desired Performance; The proposed 10 mm × 10 mm frequency selective surface unit cell structure rejects the frequency band of 2-14 GHz covering WiMAX, WLAN, and X band in-service frequency ranges. It has three resonant frequencies and works well in various incident angles. There is a good match between the simulated results and the tested results. Stable frequency response, simple structure, and easy production are useful features of the developed scheme.

Electrical Size Reduction of Microstrip Antennas by Using Defected Ground Structures Composed of Complementary Split Ring Resonator

E. M. Kucukoner, A. Cinar, U. Kose, E. Ekmekci — Sat, 10 Apr 2021 00:00:00 +0200

In this study the effects of using defected ground structures (DGS) composed of a complementary split ring resonator (CSRR) and CSRR with dumbbell (CSRR-D) for rectangular microstrip antennas are investigated. On this aim, two different antennas, which are Antenna B having CSRR etched DGS and Antenna C having CSRR-D etched DGS are designed and fabricated in comparison with the ordinary rectangular patch antenna, which is Antenna A. In both Antennas B and C, CSRR structures are etched in the same position of the ground planes. On the other hand, another ordinary microstrip antenna, called Antenna D, is designed at resonance frequency of Antenna C. For the characterization; resonance frequencies, voltage standing wave ratios, percentage bandwidths, gains, ka values and gain radiation patterns are investigated both in simulations and experiments. The numerical analyses show that 29.39% and 44.49% electrical size reduction (ESR) ratios are obtained for Antenna B and Antenna C, respectively in comparison to Antenna A. The experimental results verify the ESR ratios with 29.15% and 44.94%. Supporting, Antenna C promises 68.12% physical size reduction (PSR) as it is compared with Antenna D. These results reveal that Antenna C is a good alternative for DGS based microstrip electrically small antennas.

High sensitive triangular photonic crystal fiber sensor design applicable for gas detection

A. Abbaszadeh, S. Makouei, S. Meshgini — Tue, 19 Jan 2021 00:00:00 +0100

A new triangular photonic crystal fiber with a based microstructure core gas sensor has been proposed for the wavelength range from 1.1μm to 1.7μm. The guiding trait of the proposed structure depends on geometric parameters and wavelength, which are numerically studied by the finite element method. According to the results, the relative sensitivity obtained as high as 75.14% at 1.33μm wavelength. high birefringence and effective area are also obtained by order of 3.75×10^-3 and 14.07 μm² finally, low confinement loss of 1.41×10^-2 dB/m is acquired at the same wavelength. The variation of the diameters in the cladding and core region is investigated and the results show that this structure has good stability for manufacturing goals. Since the results show the highest sensitivity at wavelengths around 1.2μm to 1.7μm, which is the absorption line of many gases such as methane (CH₄), hydrogen fluoride (HF), ammonia (NH3), this gas sensor can be used for medical and industrial applications.

A Dynamic Invasive Weeds Optimization Applied to Null Control of Linear Antenna Arrays with Constrained DRR

E. Kenane, H. Bakhti, M. Bentoumi, F. Djahli — Sat, 10 Apr 2021 00:00:00 +0200

In the present work, a dynamic stochastic method is proposed and used for the synthesis of uniform linear antenna arrays. The proposed method combines the classical invasive weeds (IWO) and the mutation process, which makes it robust, simple and shows flexibility to be adapted. The dynamic IWO applies the mutation process in the calculation of standard deviation during the spatial dispersal process of produced seeds while keeping the mean at the parent plants. In the mutation process, if special conditions were achieved, the standard deviation would be re-initialized. This proposed method tries to achieve an optimal array pattern by acting on the relative amplitude excitation of each element in the linear array for an optimal inter-element spacing. The optimal array pattern has deep or broad nulls in some directions of interferences with low sidelobes level. The objective of the synthesis is to get amplitude excitations with low dynamic range ratio (DRR), which facilitates the design of beamforming feed network. To illustrate the robustness of the proposed method, numerical examples are presented and compared with the obtained results using bees algorithm (BA), bacterial foraging algorithm (BFA), real genetic algorithm (RGA), and the corresponding reference array pattern for each example.

Modelling EM-Coupling on Electrical Cable-Bundles with a Frequency-Domain Field-to-Transmission Line Model Based on Total Electric Fields

Mon, 07 Dec 2020 00:00:00 +0100

This article deals with modelling of EM-coupling on cable-bundles installed in 3D structures. It introduces a modified-Field-to-Transmission-Line model for which the specificity is to account for the reciprocal interaction between EM-fields and induced currents by considering equivalent total field sources. The first part of the paper is devoted to the derivation of this model starting from Agrawal’s classical Field-to-Transmission-Line applied on a two-wire Transmission-Line and leads to a Transmission-Line model in which the signal-wire is now referenced to a fictitious surrounding cylinder acting as a return conductor. The modified-Field-to-Transmission-Line model is then obtained by modifying this derived-model in such a way that is made compatible with numerical approaches and tools based on Agrawal’s Field-to-Transmission-Line model. This modification involves a k_L coefficient equal to the ratio of the two per-unit-length inductances of the classical and derived Field-to-Transmission-Line models. Validations of this modified formulation clearly show the capability of this model to predict precise wire responses including EM-radiation losses. The second part of the paper is devoted to its extension to Multiconductor-Transmission-Line-Networks. The process relies on the capability to define an equivalent wire model of the cable-bundle in order to derive the k_L coefficient and to numerically evaluate equivalent total field sources. Validation of this extrapolation is presented on a real aircraft test-case involving realistic cable-bundles in order to assess the potentiality of the method for future problems of industrial complexity.

Design of a Super Compact UWB Filter Based on Hybrid Technique with a Notch Band Using Open Circuited Stubs

H. El Omari El Bakali, H. Elftouh, A. Farkhsi, A. Zakriti, M. El Ouahabi — Wed, 16 Dec 2020 00:00:00 +0100

This paper presents a new design of a super compact Ultra wideband (UWB) band-pass filter (BPF) with rejection of X-band satellite applications. For covering the UWB bandpass, the proposed filter is realized using hybrid technique which is achieved by using a Microstrip-Coplanar waveguide-Microstrip transition. The basic structure consists of a modified microstrip in the top layer and CPW in the bottom layer. Later, open-circuited stubs are embedded in the top to implement in-band transmission zeros (TZ) so as to circumvent interference. The simulated results show that the UWB bandpass filter has a high adaptation (S₁₁ ≤ −18 dB) and insertion loss better than 0.4 dB at the passband. The impedance bandwidths are about 114% (3–11 GHz) with upper stopband extends to more than 14 GHz with a depth of greater than 38 dB. In addition, the UWB BPF shows a flat group delay performance with a variation of about 0.15 ns over the entire bandwidth. A prototype of the filter is fabricated and tested. Good agreement is achieved between measurement and simulation. The proposed UWB BPF is compact in size with overall dimensions of 14 by 9.2 mm². Consequently, the obtained results prove that the presented filter is suitable for UWB wireless devices.

Accurate Hysteresis Loops Calculation Under the Frequency Effect Using the Inverse Jiles-Atherton Model

I. Belgasmi, M. Hamimid — Thu, 12 Nov 2020 00:00:00 +0100

In this present work, an attempt has been made to improve the shape of hysteresis loops as well as an accurate calculation of the iron losses under the frequency effect. The inverse Jiles-Atherton model is extended to describe the magnetization of ferromagnetic material behavior in dynamic regime. A new formulation of the magnetic effective field is used which consists of modifying the expression of the excess field to take correctly into account the moving domain walls effect. The new proposed expression of the effective field allows a good representation of the magnetic hysteresis behavior regarding the frequency increase. To validate this proposal approaches a measured and modeled hysteresis loops for different frequencies are compared.

Tri-Band Slot-Loaded Microstrip Antenna for Internet of Things Applications

S. Mohamed Refaat, A. Abdalaziz, E. K. I. Hamad — Wed, 17 Mar 2021 00:00:00 +0100

A new design of a multiband microstrip patch antenna using slots in the patch as well as defected ground structures (DGS) implemented in the ground plane is proposed. Multi resonance response was obtained by etching the DGS shapes in the ground plane of a Traditional patch operates at 5.2 GHz, which is the common frequency for the Internet of Things (IoT) applications. The novel outcome of this work is a compact antenna that resonates at three bands, viz. 2.42, 5.22 and 5.92 GHz. Different shapes of slots were used to improve the antenna performance at the different resonances. The antenna used the inset feeding technique to improve impedance matching. Rogers RO3003 substrate of 3 relative dielectric constant, 0.0013 loss tangent, and 1.5 mm thickness was used to build the antenna. The designed antenna was simulated using HFSS software. The good consistency between simulations and measurements confirmed the antenna's ability to improve the benefits for IoT applications at the three different frequencies.

Virtual Prototype of Innovative Ka-Band Power Amplifier Based on Waveguide Polarizer

S. Fantauzzi, L. Valletti, F. Di Paolo — Wed, 14 Oct 2020 00:00:00 +0200

This paper outlines an innovative approach to design a spatial power-combining structure based on waveguide polarizers. It presents the 3D CAD model of the new structure with the transversal probes and considerations in positioning and optimization of them. Exploiting the transformation of the dominant input mode TE₁₀ into an elliptically polarized wave, provided by the polarizer, it has been possible to achieve a division of power by eight, completely carried out in space. With the insertion of the transversal probes made by microstrips, the RF signal can be sent to the MMIC solid state power amplifiers, and then recombined in the output section. Thanks to the large number of power divisions made in the waveguide section, the insertion loss of the power divider/combiner is less than 0.5 dB across the 32-34 GHz band, achieving a great power density as well. At the Author’s best knowledge, this is the first work where a waveguide polarizer is used in Spatial Power Combining technology.