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The main objective of this work is to investigate the combinatory effects of both uniaxial magnetic and electrical anisotropies on the input impedance, resonant length and the mutual coupling between two dipoles printed on an anisotropic grounded substrate. Three different configurations: broadside, collinear and echelon are considered for the coupling investigation. The study is based on the numerical solution of the integral equation using the method of moments through the mathematical derivation of the appropriate Green’s functions in the spectral domain. In order to validate the computing method and evaluated MatlabⓇ calculation code, numerical results are compared with available literature treating particular cases of uniaxial electrical anisotropy; good agreements are observed. New results of dipole structures printed on uniaxial magnetic anisotropic substrates are presented and discussed, with the investigation of the combined electrical and magnetic anisotropies effect on the input impedance and mutual coupling for different geometrical configurations. The combined uniaxial (electric and magnetic) anisotropies provide additional degrees of freedom for the input impedance control and coupling reduction. This work was supported in part by the Electronic Components and Systems (ECSEL) Joint Undertaking, which is part of the POSITION-II Project under Grant Ecsel-7831132- Position-II-2017-IA, www.position-2.eu, in part by Fundação para a Ciência e a Tecnologia-Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES) through National Funds and co-funded European Union (EU) Funds under Project UIDB/50008/2020-UIDP/50008/2020, in part by the General Directorate of Scientific Research and Technological Development (DGRSDT)-Ministry of Higher Education and Scientific Research (MESRS), Algeria, and in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI-Agencia Estatal de Investigación- al Fondo Europeo de Desarrollo Regional (AEI/FEDER), UE) under Grant RTI2018-095499-B-C31.

In this paper a metamaterial-inspired T-matching network is directly imbedded inside the feedline of a microstrip antenna to realize optimum power transfer between the front-end of an RF wireless transceiver and the antenna. The proposed T-matching network, which is composed of an arrangement of series capacitor, shunt inductor, series capacitor, exhibits left-handed metamaterial characteristics. The matching network is first theoretically modelled to gain insight of its limitations. It was then implemented directly in the 50- Ω feedline to a standard circular patch antenna, which is an unconventional methodology. The antenna's performance was verified through measurements. With the proposed technique there is 2.7 dBi improvement in the antenna's radiation gain and 12% increase in the efficiency at the center frequency, and this is achieved over a significantly wider frequency range by a factor of approximately twenty. Moreover, there is good correlation between the theoretical model, method of moments simulation, and the measurement results. This work was supported in part by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER,UE), under Grant RTI2018-095499-B-C31, in part by the British Council (UK-China-BRI Countries Education Partnership Initiative 2019), in part by the Innovation Programme under Grant H2020-MSCA-ITN-2016 SECRET-722424, and in part by the U.K. Engineering and Physical Sciences Research Council (EPSRC) under Grant EP/E022936/1.

Multiple-input multiple-output (MIMO) antennas with four and eight elements having connected grounds are designed for ultra-wideband applications. Careful optimization of the lines connecting the grounds leads to reduced mutual coupling amongst the radiating patches. The proposed antenna has a modified substrate geometry and comprises a circular arc-shaped conductive element on the top with the modified ground plane geometry. Polarization diversity and isolation are achieved by replicating the elements orthogonally forming a plus shape antenna structure. The modified ground plane consists of an inverted L strip and semi ellipse slot over the partial ground that helps the antenna in achieving effective wide bandwidth spanning from (117.91%) 2.84–11 GHz. Both 4/8-port antenna achieves a size of 0.61 λ × 0.61 λ mm2 (lowest frequency) where 4-port antenna is printed on FR4 substrate. The 4-port UWB MIMO antenna attains wide impedance bandwidth, Omni-directional pattern, isolation &gt, 15 dB, ECC &lt, 0.015, and average gain &gt, 4.5 dB making the MIMO antenna suitable for portable UWB applications. Four element antenna structure is further extended to 8-element configuration with the connected ground where the decent value of IBW, isolation, and ECC is achieved.

A compact PIN diode frequency reconfigurable dielectric resonator antenna (DRA)for GSM, LTE and 5G applications is studied and presented. The proposed antenna provides operating frequencies between 1.80 GHz, 2.6 GHz, 3.6 GHz and the lower 5G bands (3.4–3.8 GHz and 3.4–3.7 GHz) which makes it suitable for mobile communication devices. The antenna structure consists of three rectangular Dielectric Resonators DR1, DR2, and DR3 with permittivities 12.85 for RD1 and RD3 and 1.96 for RD2, of different dimensions. Two PIN diode switches are adequately placed on the microstrip line between the two dielectric resonators to assure the reconfiguration function. The proposed antenna size is $20 \times 36 \times 4.8$ mm 3. Simulation results are presented and discussed. For the antenna structure validation and to highlight its performances, the results are compared with data published in the literature. The proposed antenna, offering suitable performance, provides three modes of operation with bandwidths of 19%, 11%, and 9%

An efficient four-elements mmWave multiple-input multiple output (MIMO) antenna is proposed for use in 5G system The proposed MIMO mmWave design operates at 35GHz and occupies an overall volume of 12.5 mm $\times 12.5$ mm $\times 0.8$ mm3. This antenna exhibits a good matching impedance at the operating frequency of 35GHz mmWave band, where an isolation greater than 25 dB, envelope correlation coefficient (ECC) less than 0.02, and diversity gain (DG) of around 10dB are obtained. The 4-elements MIMO mmWave antenna also shows a peak gain of 6 dBi with 87% of peak radiation efficiency. The obtained results along with size miniaturization signify that the proposed MIMO antenna is deemed as an appropriate candidate for millimeter wave based wireless applications.

A theoretical study of the electromagnetic propagation in a complex medium suspended multilayer coplanar waveguide (CPW) is presented. The study is based on the generalized exponential matrix technique (GEMT) combined with Galerkin&rsquo, s spectral method of moments applied to a CPW printed on a bianisotropic medium. The analytical formulation is based on a Full-GEMT, a method that avoids usual procedures of heavy and tedious mathematical expressions in the development of calculations and uses matrix-based mathematical expressions instead. These particularities are exploited to develop a mathematical model for the characterization of wave propagation in a three-layer shielded suspended CPW structure. This study is based on the development of mathematical formulations in full compact matrix-based expressions resulting in Green&rsquo, s functions in a matrix form. The implemented method incorporates a new accelerating procedure developed in the GEMT which provides an initial value used to speed up searching for the exact solution in the principal computation code. This helped us to obtain accurate solutions with tolerable computing time. Good agreements have been achieved with the literature in terms of accuracy and rapid convergence. The results for different cases of bianisotropy have been investigated, and particularly, the effect on the dispersion characteristics is presented and compared with the isotropic case.

A compact dielectric resonator antenna for ultrawideband vehicular communication applications is proposed. Two cylindrical dielectric resonators are asymmetrically located with respect to the center of an offset rectangular coupling aperture, through which they are fed. Optimizing the design parameters results in an impedance bandwidth of 21%, covering the range from 5.9 to 7.32 GHz in the lower-band and a 53% relative bandwidth from 8.72 to 15 GHz in the upper-band. The maximum achieved gain is 12 dBi. Design details of the proposed antenna and the results of both simulations and experiment are presented and discussed. &nbsp

In this paper, the gyrotropic bi-anisotropy of the chiral medium in substrate constitutive parameters (ξc and ηc )o f a rectangular microstrip patch antenna is introduced in order to observe its effects on the complex resonant frequency, half-power bandwidth and input impedance. Numerical calculations and analysis based on the dominant mode are carried out to show that the latter is directly related to the former. This paper is based on the Moment Method as full-wave spectral domain approach using sinusoidal basis functions. Two new results, namely the appearance of the difference (ξc − ηc )a nd sum (ξc + ηc )o f the two magneto-electric elements are obtained in the electric transverse components and Green tensor expressions, respectively. These new results can be considered as a generalisation form of the previously published work.

A compact four-element multiple-input multiple output (MIMO) antenna is proposed for medical applications operating at a 2.4 GHz ISM band. The proposed MIMO design occupies an overall volume of 26 mm &times, 26 mm &times, 0.8 mm. This antenna exhibits a good impedance matching at the operating frequency of the ISM band, whose performance attributes include: isolation around 25 dB, envelope correlation coefficient (ECC) less than 0.02, average channel capacity loss (CCL) less than 0.3 bits/s/Hz and diversity gain (DG) of around 10 dB. The average peak realized gain of the four-element MIMO antenna is 2.4 dBi with more than 77 % radiation efficiency at the frequency of interest (ISM 2.4 GHz). The compact volume and adequate bandwidth, as well as the good achieved gain, make this antenna a strong candidate for bio-medical wearable applications.

A theoretical analysis of a printed dipole antenna on a gyrotropic-anisotropy chiral dielectric substrate is presented. The study is based on numerical techniques for the characterization of electromagnetic propagation in chiral media. The general complex wave equation and the dispersion relation for such a medium are derived in the spectral domain. The spectral Green's function of a grounded dielectric chiral slab is developed, and the spectral domain moment method impedance matrix elements are calculated. The effect of the chiral gyrotropy element on the input impedance of a dipole antenna printed on a grounded chiral substrate is analyzed using the Galerkin-based Method of Moments.

In this paper, investigations are being given to improve the antenna performance. A dielectric resonator antenna (DRA) is designed and simulated using the commercial software HFSS, the circular with other sections slot coupled technique is used to enhance the bandwidth in particular and the antenna improve the antenna performance in general. And the antenna 1.08 GHz and 1.75GHz &nbsp

Two dielectric resonators antenna (DRA) fed through slotted microstrip line for a wideband application is proposed. The two cylindrical DRs are asymmetrically situated with respect to the rectangular coupling aperture center with a defected ground plane. By optimizing the design parameters, two antenna configurations have been achieved: the first covering an impedance bandwidth of about 57%, from 8.02GHz to 14.55 GHz with power gain of 10dBi, and the second having an impedance bandwidth of about 54%, from 8.5GHz to 14.7 GHz, and a power gain of 12dBi. Results of the proposed antennas are presented and discussed.

In this paper, a new miniaturized compact dual-band microstrip slot antenna is presented. To achieve the dual-band characteristics, two adjunct partial arc-shaped small slots are joined to two main circular slots embedded in the ground of the antenna structure. With a reduced size of 30 &times, 28.5 &times, 0.8 mm3, the proposed antenna presents a dual-band characteristic. The design is optimized using a High Frequency Structure Simulator (HFSS) followed by experimental verifications. An impedance bandwidth, for S11&le, 10 dB, that covers the 1.8 GHz and 2.4 GHz bands is accomplished, which makes the proposed antenna basically suitable for hand-held devices and medical applications. More applications such as digital communication system (DCS) 1.71&ndash, 1.88 GHz, personal communication services (PCS) 1.85&ndash, 1.99 GHz, Universal and mobile telecommunications system UMTS 1.92&ndash, 2.17 GHz, Bluetooth 2.4&ndash, 2.5 GHz, and Wi-Fi 2.4&ndash, 2.454 GHz, Industrial Scientific and Medical radio frequency (RF) band ISM-2.4 GHz, Wireless Local Area Network (WLAN-2.4)are possible by simply changing one of the geometrical antenna dimensions. The antenna is characterized by stable radiation patterns as well.

A theoretical study of electromagnetic wave propagation in parallel plate chirowaveguide is presented. The waveguide is filled with a chiral material having diagonal anisotropic constitutive parameters. The propagation characterization in this medium is based on algebraic formulation of Maxwell’s equations combined with the constitutive relations. Three propagation regions are identified: the fast-fast-wave region, the fast-slow-wave region, and the slow-slow-wave region. This paper focuses completely on the propagation in the first region, where the dispersion modal equations are obtained and solved. The cut-off frequencies calculation leads to three cases of the plane wave propagation in anisotropic chiral medium. The particularity of these results is the possibility of controlling the appropriate cut-off frequencies by choosing the adequate physical parameters values. The specificity of this study lies in the bifurcation modes confirmation and the possible contribution to the design of optical devices such as high-pass filters, as well as positive and negative propagation constants. This negative constant is an important feature of metamaterials which shows the phenomena of backward waves. Original results of the biaxial anisotropic chiral metamaterial are obtained and discussed.

A compact dielectric resonator antenna (DRA) for wideband applications is proposed with a slotted microstrip line antenna. Two cylindrical dielectric resonators, which are asymmetrically located with respect to the center of rectangular coupling aperture, are feds through the aperture of the ground plan. By optimizing the design parameters, an impedance bandwidth of about 46%, covering the frequency range from 9.1GHz to 14.6 GHz, and a simulated gain of 8dBi are obtains. The simulated design details of the proposed antenna and results are presents and discussed.