Authors:
Aman;Vineet Singh;Somak Bhattacharyya;
Pages: 701 - 706 Abstract: In this study, a novel time-domain multiple reflection method for determining the electrical properties and thickness of the sample has been proposed. The unique advantage of this method is that it employs only reflection coefficient data for the reconstruction of the properties. The proposed scheme is validated by determining the permittivity, thickness, and loss tangent values of different samples of different thicknesses with high accuracy. The experimental characterisation has been carried out, incorporating the proposed scheme for its verification and thereby the electrical and physical properties of an unknown sample have been retrieved. The proposed method is simple, cost-effective and non-iterative in nature. The proposed technique is quite useful in applications like through-wall imaging, where the wall can be accessed from a single side only, monitoring the health of the building and ground-penetrating radar. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Lei Xing;Jiajia Zhu;Qian Xu;Yongjiu Zhao;Chaoyun Song;Yi Huang;
Pages: 707 - 711 Abstract: A generalised probe method is proposed for fast and accurate complex permittivity measurements. The method is based on the simulated reflection coefficients using the finite difference frequency domain method. A database is set up, which consists of the simulated complex reflection coefficients of the unknown material under test. A fast searching algorithm is performed to match the measured reflection coefficients to the reference values in the database, thus the complex permittivity of the liquid can be obtained. An in-house measurement system is developed. The unique feature of this system is that it can be applied to an arbitrarily-shaped probe. Liquid samples are measured and the results are compared with that published in the literature. Good agreements are obtained. These results could be useful for liquid microwave component designs and applications. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Alexander Bondarik;Daniel Sjöberg;
Pages: 712 - 717 Abstract: An array antenna design based on a gridded parasitic patch stacked microstrip antenna element is presented. The radiating part in the top layer of one antenna element has nine rectangular metal patches placed in a grid with three rows and three columns with a separation of 0.1 mm between the patches. Two means of realising the array are investigated. In a regular 2 x 2 concept, the parasitic patches of individual elements are placed next to each other, forming on the top layer a uniform grid of parasitic patches with six rows and six columns. In an alternative concept named as shared array, neighbouring antenna elements share one row and one column of parasitic patches, forming on the top layer a uniform grid of parasitic patches with five rows and five columns. The antenna arrays are designed for the 60 GHz band. The measured bandwidth is 13.8 GHz for the single antenna, 15.3 GHz for the 2 × 2 array, and 12.4 GHz for the shared array. The measured realised gain at 60 GHz is 6 dBi for the single antenna, 11 dBi for the 2 × 2 array, and 10.5 dBi for the shared array. The measured radiation patterns have good agreement with simulations. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Karan Gumber;Meenakshi Rawat;
Pages: 718 - 727 Abstract: Analogue predistorter (APD) has gained a new significance due to the need for high bandwidth in the fifth generation (5G) communication. As predistorted signal is generated in the analogue domain, it is free from data converter bandwidth limitation and presents an attractive linearisation solution for power amplifier (PA) in the 5G base station. Furthermore, it also finds its application in the multicarrier repeater system for long-distance communication, where the baseband information is not readily available. However, the performance of the conventional APD is dependent on the appropriate control of gain and phase of the predistorted signal. The state-of-the-art work in analogue linearisation solutions mostly utilises vector multiplier for such a control. This work points out the limitations of such a scheme and proposes a novel control scheme (CS) that is capable of extracting better benefits of the APD. An experimental validation is carried out by linearising 10 W HMC8500 broadband GaN PA, excited by a eight-component carrier 160 MHz ultra-broadband long-term evolution signal. The proposed Type-II CS delivers an adjacent channel power ratio of -45.05 dBc with an improvement of 18 dB, which is 4 dB better than Type-I CS. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Jeong-Ung Yoo;Hae-Won Son;
Pages: 728 - 733 Abstract: This study presents a novel radial uniform circular array (UCA) antenna for quad-mode orbital angular momentum (OAM) multiplexing in the 5.2 GHz band. The antenna can simultaneously generate four OAM modes (±1, ±2) using two radial UCAs printed concentrically on a single substrate. Each UCA is connected to an individual dual-mode feeding network, and generates a pair of complementary OAM modes. The feeding network for each UCA consists of one quadrature hybrid coupler and two circular feedlines, and they can be integrated onto a single substrate. The measured radiation patterns and helical phase wavefronts show the successful generation of four OAM modes by the proposed antenna. The quad-mode OAM transmission test was performed using two prototypes of the proposed antenna, and good isolations>13.7 dB were obtained between four OAM mode channels, which demonstrates that the antenna can be successfully used for OAM multiplexing. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Gaoya Dong;Weimin Wang;Yongle Wu;Yuanan Liu;Manos M. Tentzeris;
Pages: 734 - 742 Abstract: In this study, a series of rat-race couplers with bandpass filtering responses and impedance transforming characteristics are presented based on novel coupled-line structures. Firstly, a novel filtering rat-race coupler core circuit is proposed by introducing coupled-line structures into conventional rat-race coupler. Then, a series of rat-race couplers with enhanced filtering responses and stopband rejections are constructed by employing various types of impedance transformers. The even- and odd-mode methods are adopted to explain the operating mechanisms. Finally, a filtering rat-race coupler prototype with a fractional bandwidth of 35.2% is designed and measured. The measured results show high passband selectivity, good out-of-band rejection and isolation performances, which is attractive for practical application. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Yuwei Zhang;Shu Lin;Baoqi Zhu;Jingxuan Cui;Yu Mao;Jianlin Jiao;Alexander Denisov;
Pages: 743 - 751 Abstract: In this study, a broadband and high gain dielectric-rod end-fire antenna are proposed for applications on both the K and Ka bands. By employing the double-ridged waveguide (DRW) feeding structure which is composed of a coaxial line to tapered DRW transition, a parabolic tapered DRW, and a parabolic-tapered flared parallel waveguide section, the impedance bandwidth of this proposed antenna is broadened to 84.5%. The dielectric-rod with the double circular truncated cone structure acted as the main radiator of the proposed antenna is adopted to achieve higher gains and lower side-lobe levels as compared to the traditional circular cone dielectric-rod, while the four-wedges structure inserted in the waveguide is developed as the matching section of the dielectric-rod to further improve the impedance matching. The measured results show that this antenna can be operated in 17.9-44.1 GHz, and the measured gain changes from 9.9 to 15.5 dBi. Moreover, the radiation patterns are demonstrated with observed end-fire characteristic in the overall operating band. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Ahmad Mamoun Khamis;Zulkifly Abbas;Ahmad F. Ahmad;Raba'ah Syahidah Azis;Daw M. Abdalhadi;Ebenezer Ekow Mensah;
Pages: 752 - 758 Abstract: Epoxy resin (ER) composites reinforced with micro-sized oil palm empty fruit bunch (OPEFB) were fabricated to improve the biodegradability of electromagnetic interference connector gasket. The dielectric properties, transmission coefficient S21 , reflection coefficient S11 , reflection loss, power loss and shielding effectiveness were studied at a frequency range of 8-12 GHz. OPEFB-ER composites were prepared by varying the percentages of OPEFB (0, 5, 10, 15, 20, 25, 30 and 40%) at room temperature (25°C ±2). Dielectric constant (ε'), loss factor (ε"), reflection and transmission coefficients of the composites were measured using rectangular waveguide connected to vector network analyser. In addition, ε' and ε" were used in finite element method technique to obtain S11 and S21 . The results showed that the dielectric properties increased but S11 and S21 decreased with increasing OPEFB percentage in the composites. The shielding effectiveness, power loss and reflection loss increased with increasing OPEFB percentage in the composites. The simulated and measured results of S11 and S21 were in good agreement. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Gaoya Dong;Weimin Wang;Yongle Wu;Yuanan Liu;Yunnan Fang;Manos M. Tentzeris;
Pages: 759 - 767 Abstract: This study presents a novel dual-band filtering power divider (DB-FPD) structure with independently controllable bandwidths for dual-band application. The proposed DB-FPD structure is constructed by shorted G- and T-shaped patch resonators, and meandered slot lines are etched on shorted patch resonators to generate resonance in the upper band. The 3 dB fractional bandwidth (FBW) of designed DB-FPD structure in a lower band (upper band) can be adjusted from 5.2 to 24.2% (3.1 to 26.9%), respectively, using a substrate of 31 mil thick TLY-5. The even-/odd-mode method is adopted to demonstrate the power splitting and isolation performances. The lumped-element equivalent circuit is extracted to explain the power splitting transmission performance. Also, the coupling matrix analysis is applied to present the detailed design procedures for practical DB-FPD, with specific passband bandwidths and centre frequencies of dual passbands. Finally, the isolation performances are analysed with different isolation resistor values and loading positions. For verification, two DB-FPDs with equal absolute bandwidths (ABW) and equal FBWs are simulated, fabricated and measured for dual-band WLAN application. The measured results agree well with the simulated ones, exhibiting a favourable frequency selectivity and controllable passband bandwidths. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Tarcísio C. Fonseca;Sandro T.M. Gonçalves;Cássio G. do Rego;Gláucio L. Ramos;
Pages: 768 - 773 Abstract: This work presents improvements for inclined thin wire simulation in finite-difference time-domain (FDTD). Modelling of the corners of staircase geometries is proposed by adding the accumulated charges at an edge region. This correction is important due to the delay of the electromagnetic fields propagation on the stairs. To test the validity of the proposition, the v-dipole fed by a resistive voltage source is designed and implemented. A significant improvement can be noted in the calculation of the impedance when the stairs of the geometry are more discretised and the charge correction is applied. Also, a surprising outcome is issued when the stair formed by an inclined thin wire has only one cell per stair: a perfect emulation of an inclined wire happens when the charge correction is applied, showing that a correction of the propagation time of the electromagnetic fields is automatically performed. Based on the propagation time adjustments, an effective length model has also been proposed to emulate the real size of the inclined wire by the size correction of the staircase geometry. Although the effective length depends on the FDTD parameters initial setup, it has a fast response and a low complexity implementation with good accuracy. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Kaijun Song;Pan Zhao;Yuxuan Chen;Shema Richard Patience;
Pages: 774 - 778 Abstract: A compact high-isolation planar eight-way power divider using a zero-phase isolation circuit is presented. The composite right- and left-handed transmission line is applied to achieve good input impedance matching, and the hybrid coplanar waveguide (CPW)/microstrip line is used to get a compact circuit size in the eight-way power-dividing circuit. In addition, the zero-phase microstrip line is applied to obtain high output isolation. The design has been verified by measurements, which show good agreement with simulations. The fabricated eight-way power divider measured results show that the central frequency of 2.2 GHz, 15 dB input return loss bandwidth of 36.4%, 0.2 dB insertion loss bandwidth of 29% and 20 dB output isolation bandwidth of 27% are achieved. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Kang Ding;Rentang Hong;Dongfang Guan;Li Liu;Yanjie Wu;
Pages: 779 - 784 Abstract: A broadband circularly polarised (CP) stacked antenna with a sequential-phase feed technique is proposed in this study. The antenna contains a square ring that is encircled by four driven patches. The gap-coupled feed method is used to transfer energy from the square ring to the driven patches. Moreover, four stacked patches are placed above the bottom layer to enhance the impedance and CP bandwidths. The measured results yield an impedance bandwidth of 33.6% (4.78-6.71 GHz) and a wide 3 dB axial ratio bandwidth of 19.4% (4.90-5.95 GHz) is obtained. The average gain is ~9 dBi and the variation of gain is PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Kamil Janeczek;Aneta Araźna;Wojciech Stęplewski;Tomasz Serzysko;
Pages: 785 - 790 Abstract: Modern electronic industry requires simultaneous monitoring of electronic devices from their production, usage, up to their recycling. Therefore, the traceability system is becoming more and more popular in this modern electronic industry. In this study, such a system working in the ultra-high frequency range was demonstrated. A functional part of the system (sensor) was produced using different technologies that aim to embed chips inside printed circuit boards. The sensors were examined under changing temperature conditions. The achieved results showed that the laminated sensors were more resistant to temperature cycles, although some voids were observed in their structures, which may influence their mechanical properties. All the tested samples remained fully functional after 500 temperature cycles (-40°C to +105°C). The values of the received signal strength indicator measured before and after the temperature exposure did not reveal significant differences. Bearing this in mind, it can be stated that the proposed system can be successfully used in the electronic industry to monitor the operation of different types of devices. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Mohamed El Atrash;Omar F. Abdalgalil;Ibrahim S. Mahmoud;Mahmoud A. Abdalla;Sherif R. Zahran;
Pages: 791 - 799 Abstract: A high gain, low specific absorption rate, oval-shaped monopole antenna is presented. It is backed by an all-textile 3 × 3 array of electromagnetic bandgap (EBG) unit cells. The antenna is printed on the thin Rogers ULTRALAM 3850 substrate, while the EBG array is composed of the conductive ShieledIT Super and dielectric substrate felt. The design operates at 2.45 GHz of the Industrial, Scientific, and Medical band. Due to the close distance between the extended grounds of the co-planar waveguide feeding configuration and the oval-shaped monopole antenna, current-coupling was achieved, leading to gain enhancement. However, with body-loading cases, resonance at 2.45 GHz was attained at a separation of 30 mm. By incorporating the EBG array, as an isolator, this issue was resolved. In free space and over a gap of 3 mm from the human body, gain enhancements by 2.68 and 11.54 dB were achieved at 2.45 GHz, respectively. Simulated and measured results are benchmarked. Furthermore, SAR simulation study showed reductions by 99.5%, averaged over 1 and 10 g of tissue. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Abdurrahim Toktas;Deniz Ustun;Mustafa Tekbas;
Pages: 800 - 811 Abstract: Multilayer radar absorbing material (MRAM) is composed by superimposing different dielectric material layers with various thicknesses for reducing the reflection of electromagnetic (EM) wave. In this study, a novel triple-objective optimisation scheme based on Pareto-integrated artificial bee colony (P-ABC) algorithm is presented for the fully-optimised design of four broad-band and broad-angle MRAMs (BB-MRAMs) at the most interested radar bands 2-8, 8-12, 12-18 and 2-18 GHz between the angle range of 0°-60°. Two objective functions depending on total reflections (TRs) with TE and TM polarisations are constituted by taking the weighted mean of the TR in the incident wave angle and frequency. The BB-MRAMs are optimally designed by determining simultaneously the design variables of the thickness and material of each layer for minimising synchronously the three objective functions TE-TR, TM-TR and total thickness through the P-ABC, as well as by assuring the trade-off among the objectives. The BB-MRAMs are also verified under various cases through a comparison with simulated results by a full-wave simulator. The designed BB-MRAMs are even compared with the near-optimal MRAMs reported elsewhere. Therefore, the fully-optimised BB-MRAMs by the proposed triple-objective scheme are the global optimal designs thanks to the robust P-ABC algorithm. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Changzhen Li;Junyi Yu;Wei Chen;Kehao Wang;Shoufeng Wang;Kun Yang;Xiaofeng Wu;
Pages: 812 - 820 Abstract: To guarantee shipping safety, it is crucial to build a reliable wireless communication network. This study presents characteristic analysis of shipping wireless channel based on measurements. The authors conduct five channel measurements for two important water mobile communications, covering inland river and sea scenarios. Channel characteristics, e.g. power delay profile, amplitude distribution, delay spread and shadow fading, are extracted and compared for the two scenarios. It is found that the main difference between the them lies in more obstacles and scatterers in inland river propagation environment. The results show that more obstacles and scatterers can result in richer multipath effect and larger shadow fading decorrelation distance. A triple Gaussian mixture distribution (TGMD) is proposed to characterize the wireless channel with LOS, obstructed LOS and non-LOS situations in the practical propagation. To verify the effectiveness of TGMD, the goodness of fit between measurement and analysis results in terms of Rician K-factor, root mean square (RMS) delay spread and RMS Doppler spread is calculated. Furthermore, the cross-correlation among shadow fading, Rician K-factor and RMS delay spread are studied. Larger cross-correlation can be found in inland river and sea than vehicular communication due to the open propagation environment. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Rinkee Chopra;Girish Kumar;
Pages: 821 - 829 Abstract: In this study, a low cost, broadband and high gain multilayer multiresonator microstrip antenna (MSA) is designed. It consists of one metallic fed patch at the bottom layer and two circular patches (1B2 T) are printed on the bottom side of the top FR4 substrate layer, which is air suspended. Two configurations with the bottom patch of circular and elliptical shapes are compared. The elliptical 1B2 T MSA provides better bandwidth (BW), i.e. 53.4% with peak gain of 9.8 dBi. The antenna design parameters are selected to provide maximum BW with uniform gain. The elliptical 1B2 T MSA is further enclosed in a metallic cavity, which improves the BW, gain and front to back (F/B) ratio of the antenna. The elliptical 1B2 T MSA with cavity enclosure is fabricated and tested. Experimental results are in agreement with simulated ones. The elliptical 1B2 T MSA with cavity provides 55.7% BW with peak gain of 12.1 dBi and F/B of>18 dB. The proposed antenna can be used in GPS, 2G, 3G, 4G and Wi-Fi frequency bands applications. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Authors:
Will P.M.N. Keizer;
Pages: 830 - 834 Abstract: This study deals with the affine transformation that is used to convert the triangular element grid of a planar phased array antenna into a square one. By means of this kind of transformation, it is possible to apply the iterative Fourier transform (IFT) method to synthesise low sidelobe tapers for array antennas featuring a triangular grid. Combination of the IFT method with an affine transformation allows the synthesis of low sidelobe tapers of which the peak sidelobe level does not vary with changing frequency and/or altering main beam position. The considered affine transformation was already briefly addressed in earlier publications of this author. In this study detailed information is given on its use in combination with the IFT method. Examples to demonstrate the effectiveness of the combination affine transformation and the IFT method for triangular grid array antennas are given. It will be shown that the peak sidelobe levels of the obtained tapers are invariant with frequency and scan angle when all far-field directions of the array factor are involved in the low sidelobe taper synthesis. PubDate:
7 1 2020
Issue No:Vol. 14, No. 8 (2020)
Hybrid journal (It can contain Open Access articles)
