Journal of Electromagnetic Waves and Applications
ISSN / EISSN : 0920-5071 / 1569-3937
Published by: Informa UK Limited (10.1080)
Total articles ≅ 5,609
Latest articles in this journal
Published: 23 September 2021
Journal of Electromagnetic Waves and Applications pp 1-16; https://doi.org/10.1080/09205071.2021.1980914
Due to the unique nonreciprocal characteristic, ferrite exhibits anisotropic behaviour in electric performance. Owing to such special phenomenon, it is difficult to efficiently analyse and simulate the ferrite material. Here, an alternative scheme is proposed for the bandpass ferrite finite-difference time-domain simulation. This algorithm is carried out which is based on approximate Crank–Nicolson procedure and incorporated with the complex method and higher-order formulation. The ferrite material can be calculated by the modified auxiliary differential equation approach according to the bandpass sampling theorem. The introduction of numerical example validates the effectiveness. As shown in the results, the proposed scheme can take advantage of these methods which can be demonstrated from the aspect of accuracy, efficiency and absorption. In addition, the proposed scheme can solve the time increment problem caused by the solution of tri-diagonal matrices during the simulation of implicit algorithms.
Published: 21 September 2021
Journal of Electromagnetic Waves and Applications pp 1-24; https://doi.org/10.1080/09205071.2021.1980913
In this article, we have developed a new mathematical model of a microwave square guide polarization converter with diaphragms. The applied model was created using the microwave theory of equivalent networks. The novelty of the developed theoretical model consists in its possibility to take into account the thickness of the diaphragms. This feature is achieved by using more accurate but complicated T- and Π-shaped equivalent networks. Theoretical analysis and optimization of a guide polarizer were performed using the scattering and transmission matrices of the diaphragms in a square guide. The parametric optimization of a guide polarizer was performed by means of the developed equivalent networks and using finite elements method in the frequency domain. The optimal sizes and electromagnetic characteristics of the polarizer, which were obtained by both methods, are in good agreement. The main advantage of the suggested mathematical model consists in the calculation time reduction. Developed compact waveguide polarizer can be used in modern satellite and radar antenna systems with circular polarization of applied electromagnetic waves.
Published: 21 September 2021
Journal of Electromagnetic Waves and Applications pp 1-11; https://doi.org/10.1080/09205071.2021.1978332
The Technique, to design multibeam Radial Line Slot Array (RLSA) antennas optimally, was proposed in this study, using high beam squint values to produce more slots. This is necessary to maintain gain, which dropped due to the beam splitting. A gap was also incorporated between the slots group to overcome a coupling between adjacent beams which can lessen gains. RLSA models for 42 dual and 42 triple-beams were simulated after which a prototype for each was measured to verify the simulation. The results showed the possibility of obtaining multibeam antennas with similar symmetrical beams in terms of beamwidth, gain, and direction. The gains obtained were 13.5 dBi for the dual-beam and 10.5 dBi for the triple-beam, indicating a difference of 3 and 4.77 dB, respectively, with the single-beam antennas, thereby, making them suitable for the theory of beam splitting. The antennas also have sufficient bandwidth and a good reflection coefficient.
Published: 21 September 2021
Journal of Electromagnetic Waves and Applications pp 1-14; https://doi.org/10.1080/09205071.2021.1978872
The analytically calculated dispersion diagram of an overmoded 9-period V-band slow-wave structure (SWS) designed to operate in a high-order transverse-magnetic TM03 waveguide mode of a backward-traveling electromagnetic wave [Ye et al., Phys. Plasmas, 22, 063104 (2015)] is re-examined using the two-dimensional (2D) Poisson SuperFish code allowing to precisely calculate spatial patterns of electric field vectors, wavenumbers and characteristic frequencies of all azimuthally-symmetric TM0nl cavity modes that exist in a closed SWS, where n and l are the radial and axial indices of TM0nl cavity modes, respectively [Main et al., IEEE Trans. Plasma Sci., Vol. 22, No. 5, Oct. 1994, p. 566]. It is shown that the analytically calculated higher-order TM0n waveguide modes of the open SWS are actually not pure TM0n modes, but fascinating combinations of selected portions of the modes with selected portions of all possible lower-order TM0(n-j) waveguide modes, where j=1 … (n-1). An analytically calculated TM03 waveguide mode, therefore, turns out to be in fact a combination of three different TM0n waveguide modes sequentially identified by numerically calculated TM0nl cavity modes: (i) TM03l mode with l=0 … 4, (ii) TM01l mode with l=13 … 11, and (iii) TM02l mode with l=8 … 9.
Published: 16 September 2021
Journal of Electromagnetic Waves and Applications pp 1-18; https://doi.org/10.1080/09205071.2021.1977184
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 estimation using phase comparison mono pulses for multi-channel signals. To verify DoA estimation error, simulation and measurement are performed using the proposed antenna system. As a result, we confirm the performance of estimating each channel's angle and the beam directional error within 0.5°.
Published: 16 September 2021
Journal of Electromagnetic Waves and Applications pp 1-19; https://doi.org/10.1080/09205071.2021.1978331
This article presents the design of a printed antenna for Direct Broadcast Satellite (DBS) (12.2 – 12.7 GHz) services. The newly designed proposed structure, named as ‘wave-fractal’, is having a considerably high gain and can heavily suppress cross-polarization level along the entire HPBW region. The radiating area of one-quadrant of structure is derived by superimposing six numbers of ‘Golden-ratio’ based squares, and it poses 2D-quadrantal symmetry. In order to resonate the structure at desired frequency, two parallel slots and a circle based defective ground structure is imposed. Furthermore, to achieve a symmetric radiation pattern, a 2D-Octagonal symmetry has been implemented on the proposed structure. The fabricated prototype resonates at 12.49 GHz and gives a gain and x-pol. as 9.52 dBi and −35.36 dB, respectively. The measured impedance bandwidth is 502 MHz, which ensures 100% bandwidth coverage for the DBS band. The measured results make an excellent agreement with its simulated counterpart.
Published: 14 September 2021
Journal of Electromagnetic Waves and Applications pp 1-10; https://doi.org/10.1080/09205071.2021.1977185
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 addition, when its unit cell structure is rotated by an angle ψ, almost ±2ψ Pancharatnam-Berry (PB) phase will be generated in its co-polarized reflection coefficient under CP incidence. Thus, base on the polarization conversion metasurface, an ultra-wideband PB 2-dit coding metasurface is further proposed for Radar Cross Section (RCS) reduction. The simulation and experiment results show that the coding metasurface can achieve more than 10 dB RCS reduction in the ultra-wide frequency band 7.2–28.6 GHz under normal incidence with arbitrary polarizations; in addition, when the incident angle is increased to 45°, the ultra-wideband RCS reduction can still be realized, which shows that the coding metasurface has good stealth performance in X, Ku and K bands, and it is very practical for most airborne radar, fire control radar and imaging radar working in these bands.
Published: 9 September 2021
Journal of Electromagnetic Waves and Applications pp 1-15; https://doi.org/10.1080/09205071.2021.1975315
A compact five-port multi-input multi-output (MIMO) antenna for n79 (4.4–5 GHz) 5G band exhibiting pattern and polarization diversity with good isolation is proposed in this paper. This MIMO antenna system comprises of four linearly polarized (LP) endfire monopole antenna elements and one broadside L-shaped slot circularly polarized (CP) antenna element, which provides both pattern and polarization diversity. A T-shaped slot as a decoupling structure is further used to improve the interport isolation by 4 dB. The return loss bandwidth for all antenna elements is in the desired frequency range, and antenna elements provide isolation better than 23 dB. The pattern and polarization diversity provide a low envelope correlation coefficient and good isolation between any two-port of the MIMO antenna. For experimental verification, the proposed 5-port MIMO antenna system is fabricated and measured, which provides decent agreement with the simulated performance.
Published: 8 September 2021
Journal of Electromagnetic Waves and Applications pp 1-17; https://doi.org/10.1080/09205071.2021.1972844
In this paper, an improved analytical model is presented to predict the shielding effectiveness (SE) and resonances of an apertured enclosure composed of the material of finite conductivity. In the model, the modified parameters of the rectangular waveguide are introduced to deal with the lossy enclosure with apertures, which can consider the effects of wall loss on the SE. Firstly, according to the circuit theory and electromagnetic topology (EMT) theory, the lossy enclosure is modeled as the circuit model and signal flow graph, respectively. Then, the electric field components at the monitor point can be obtained; hence, the SE can be predicted accurately. Finally, the presented model is utilized to analyze the effects of various parameters and conditions on the SE. The validity of the presented model is verified by the CST through several cases, showing that the lossy enclosure is feasible to damp all the resonant modes.
Published: 8 September 2021
Journal of Electromagnetic Waves and Applications pp 1-11; https://doi.org/10.1080/09205071.2021.1975574
When reinforced with conductive fibers, woven composites can exhibit interesting shielding properties. This paper focuses on their response for obliquely incident plane waves in the high-frequency range (500 MHz to 40 GHz). A two-step homogenization technique is carried out. First, the composite response (shielding effectiveness and reflection coefficient) is computed using a 3D finite element simulation, then the effective properties are estimated by implementing an optimization process to solve the inverse problem. Results show that composites effective properties are independent of the angle of incidence and wave configuration. This suggests that oblique incidence scenarios can be studied by homogenizing the material based on the case of normal incidence.