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The novel T-shaped patch antenna with the superstrate approach is planned in the manuscript. The FR-4 dielectric material is used as a superstrate and substrate. The hexagonal-shaped rings are loaded in the superstrate to enable the metamaterial property in the structure. The copper-loaded metamaterial and liquid Sea water-loaded metamaterial are used in the planned antenna which increases the gain and BW of the planned antenna design. Different parametric analyses like the varying height of the superstrate and changing spacing among SRR rings are considered to achieve an optimum response. The analysis concerning S11, gain, and directivity is carried out among simple patch antenna, copper ring loaded structure and seawater loaded structure. The frequency span of 1 GHz to 12 GHz is considered for analysis. The planned designs provide a minimum S11 of −49.16 dB in CMRNGS, a Gain of 6.92 dB in SMRNGS, and a highest directivity of 8.56 dB for 8.83 GHz resonance. The planned design is compared with other papers to check the improvement of this planned antenna design. The Simulated and assessed responses were also compared and analysed. The planned design is suitable for 5G, WLAN, tracking and detection applications.

Abstract Sb2S3 is rapidly developed as light absorber material for solar cells due to its excellent photoelectric properties. However, the use of the organic hole transport layer of Spiro‐OMeTAD and gold (Au) in Sb2S3 solar cells imposes serious problems in stability and cost. In this work, low‐cost molybdenum (Mo) prepared by magnetron sputtering is demonstrated to serve as a back electrode in superstrate structured Sb2S3 solar cells for the first time. And a multifunctional layer of Se is inserted between Sb2S3/Mo interface by evaporation, which plays vital roles as: i) soft loading of high‐energy Mo particles with the help of cottonlike‐Se layer; ii) formation of surficial Sb2Se3 on Sb2S3 layer, and then reducing hole transportation barrier. To further alleviate the roll‐over effect, a pre‐selenide Mo target and consequentially form a MoSe2 is skillfully sputtered, which is expected to manipulate the band alignment and render an enhanced holes extraction. Impressively, the device with an optimized Mo electrode achieves an efficiency of 5.1%, which is one of the highest values among non‐noble metal electrode based Sb2S3 solar cells. This work sheds light on the potential development of low‐cost metal electrodes for superstrate Sb2S3 devices by carefully designing the back contact interface.

This paper presents a new radar sensor configuration of a planar grid antenna array (PGAA) for automotive ultra-wideband (UWB) radar applications. For system realisation, the MIMO concept is adopted. The proposed antenna is designed to operate over the 24 GHz frequency band. It is based on split-ring resonator (SRR) elements to enhance the operating bandwidth and increase the antenna gain, leading to a better-performing radar system. The PGAA consists of thirty-one radiating elements, in which each element excitation is obtained using a common transmission line centre fed by a 50 Ω coaxial probe. By introducing a superstrate dielectric layer at a distance of λ/2 from the top of the antenna array, the PGAA gain and impedance bandwidth are further improved. The gain is improved by 2.7 dB to reach 16.5 dBi at 24 GHz, and the impedance bandwidth is enhanced to 9.3 GHz (37.7%). The measured impedance bandwidth of the proposed antenna array ranges from 20 GHz to 29.3 GHz for a reflection coefficient (S11) of less than −10 dB. The proposed antenna is validated for automotive applications.

This paper reports a model to determine effective permittivity (εeff) and resonant frequency (fr) of microstrip patch antenna (MPA) covered with multiple dielectric layers. This model is augmented with a newly developed empirical expression to determine the εeff of multi-layered superstrates over a substrate. The development of empirical formulation makes use of conformal mapping approach (CMA) and series-parallel combination of dielectric boundaries between the ground plane and patch of the MPA. In this work, the MPA is designed on substrate having dielectric constant of ε1 whereas the superstrate layers have dielectric constants of ε2, ε3 ...εn. It is shown that the proposed technique is able to predict the fr of MPA with error of 1.8%, 3.5%, and 1.4% when it is covered with a single dielectric layer with superstrate height of 4.5mm for respective conditions of ε1 = ε2, ε1 > ε2 and ε1 2 (ε1 = 3.66, ε2 = 2.2/4.7). Furthermore, the developed technique is analyzed for distinct combination of substrate and two superstrate layers for the cases ε1 = ε2 > ε3, ε1 = ε2 3, ε1 2 > ε3, ε1 > ε2 3, and ε1 > ε2 > ε3. Subsequently, the viability of the proposed technique is demonstrated in practical scenarios for body centric communications by considering single (e.g., jeans cotton, pure cotton, rayon, polyester, felt fabric, terry wool, and leather) and multiple (e.g., wool over jeans cotton and polyester, felt fabric over pure cotton and rayon) layers of textiles over MPA. The measurement results on various dielectric superstrates and textiles show excellent agreement with the corresponding theoretical results and thereby validate the reported theory. Finally, a comparison with the seminal works clearly shows the promise of the reported technique in this paper.

In this paper, a ε-negative metasurface superstrate is proposed for mutual coupling reduction of large antenna arrays. Unlike the previous decoupling metasurface works that are mostly confined to two-ports antennas, the proposed decoupling superstrate can be extended to massive multiple-input multiple-output (MIMO) systems. A 4 × 4 antenna array is used as an example to illustrate the decoupling performance of the proposed metasurface. With the decoupling metasurface, the worst mutual coupling of the antenna array is improved by 8 dB over the operation bandwidth with a maximum mutual coupling reduction of 25 dB. Moreover, the decoupling metasurface also help restore the radiation patterns, bring down the active voltage sanding wave ratio, and broaden the bandwidth of the array.

A wide-band metasurface inspired polarization reconfigurable antenna with a low profile and a simple DC controlling circuit is introduced and analyzed in this paper. The proposed antenna consists of three parts, i.e., a coplanar waveguide-fed slot coupling antenna with slot slanted angle of 40 degrees, a metasurface superstrate which is composed of a 3·4 array of metallic rectangular patches, and a simple DC bias controlling circuit including p-i-n diode switches, metallic vias, chip inductors, and bias lines. When all the p-i-n diode switches are in ON state, the antenna will work in linear polarization state and generates linear polarized (LP) wave, the measured operating band ranges from 5.2 to 6.2 GHz (17.5% -10 dB impedance bandwidth), while the measured average realized gain is 6.2 dBi. When all the PIN diode switches are in OFF state, the polarization state of the antenna will alter to left-handed circular polarization and produces left-handed circular polarized wave, the measured -10 dB impedance bandwidth and 3 dB axial ratio bandwidth are 20.7% (ranges from 5.2 to 6.4 GHz) and 15.1% (ranges from 5.5 to 6.4 GHz), respectively, while the average realized gain is 7.1 dBi. Measured results of the reflection coefficients, realized gains at broadside, axial ratio, and radiation patterns are in good agreement with numerical simulations, which verifies the effectiveness and correctness of the proposed design.

In this paper, a symmetrical monolayer metamaterial superstrate is placed on a microstrip patch antenna resonant at 3.5 GHz. MTM metamaterial based CSRR Complementary Split Ring Resonators, constituting two rectangular rings is opposite splits on both ends, which are printed on Rogers RT 5880 type substrate with relative permittivity of 2.2, tangential loss of 0.0009, and a thickness of 0.508mm. This resonator is capable of exhibiting an ε-negative permittivity. Moving an MTM superstrate loaded with a 2 × 3 grating on a single radiating element, provides a gain increase from 4.66 dBi to 5.67 dBi was found at its operating frequency, and the radiation pattern was directional and stable over the entire frequency band. For a 4×1 antenna array loaded with MTM, the gain reaches about 9.84 dBi. the proposed antenna is suitable for 5G mobile applications.

Gain and bandwidth enhancement of low profile, linearly polarized square dense dielectric patch antennas using a frequency selective surface (FSS) superstrate layer is proposed. A high dense dielectric patch antenna is utilized as a radiating element instead of a metallic patch in order to gain several significant advantages, including low profile, wide bandwidth, and high radiation efficiency. The implemented antenna is excited by an aperture-coupled feeding technique. The antenna gain is enhanced by using a highly reflective FSS superstrate layer, realizing an antenna gain enhancement of 11 dBi. The implemented antenna acquired a measured gain of about 17.78 dBi at 28 GHz with a 9% bandwidth and radiation efficiency of 90%. The bandwidth of the proposed antenna is improved by using a unit cell printed on two sides, as it provides a positive phase gradient over the desired frequency range. The antenna impedance bandwidth is broadened and the measured impedance matching S11 exhibited a 15.54% instead of 9% bandwidth while maintaining a high-gain characteristic of about 15.4 dBi. The implemented antenna presents a solid radiation performance with good agreement between the measured and simulation results. For some attractive advantages such as low profile, low cost, lightweight, small size, and ease of implementation, the proposed antenna is a very good candidate for millimeter-wave wireless communications.

The idea of passive biosensing through inductive coupling between antennas has been of recent interest. Passive sensing systems have the advantages of flexibility, wearability, and unobtrusiveness. However, it is difficult to build such systems having good transmission performance. Moreover, their near-field coupling makes them sensitive to misalignment and movements. In this work, to enhance transmission between two antennas, we investigate the effect of superstrates and metamaterials and propose the idea of dielectric fill in between the antenna and the superstrate. Preliminary studies show that the proposed method can increase transmission between a pair of antennas significantly. Specifically, transmission increase of ≈5 dB in free space and ≈8 dB in lossy media have been observed. Next, an analysis on a representative passive neurosensing system with realistic biological tissues shows very low transmission loss, as well as considerably better performance than the state-of-the-art systems. Apart from transmission enhancement, the proposed technique can significantly mitigate performance degradation due to misalignment of the external antenna, which is confirmed through suitable sensitivity analysis. Overall, the proposed idea can have fascinating prospects in the field of biopotential sensing for different biomedical applications.

Je přirozené, že se jednotlivé jazyky od sebe liší. Díky těmto rozdílům mluvíme o samostatných jazycích. Jazykovou interferencí rozumíme vzájemné přejímání některých jazykových prostředků z jednoho jazyka do druhého. Výskyt interference podmiňují různé faktory, např.: 1) nedostatečné ovládání cizího jazyka; 2) značná podobnost mezi cílovým a mateřským jazykem; 3) slabá koncentrace mluvčího. Tento příspěvek si klade za cíl zdůraznit mechanismy vedoucí k interferenci a její následky.

This research has proposed a switchable beam rectangular microstrip antenna with double parasitic patches, in which two PIN diodes were deployed for manipulation of the main beam direction and a superstrate (i.e. either a dielectric slab or metamaterial) for enhancement of the antenna gain. The dielectric slab is a second FR4 substrate while the metamaterial (MTM) is the 7×17 periodic structure of planar cycloid dipoles (PCD). Simulations were carried out and three different antenna prototypes (i.e. the proposed switchable beam rectangular microstrip antenna, the proposed antenna either with dielectric slab or MTM) fabricated and experimented. The simulation and experimental results are in good agreement and exhibit good impedance matching (|S11| less than 10dB) along the operating frequency. The average measured gain is 7 dBi with the unidirectional radiation pattern along the operating frequency. The proposed switchable antennas with and without the superstrate are operable in the 2.4-2.5 GHz WLAN system and switchable in three directions of 0 deg, 30 deg and 330 deg (xy-plane). Moreover, the findings validate the applicability of either the dielectric slab or three MTM block-layers as the superstrate to improve the antenna gain.

This paper presents a high-gain and wideband antenna with a compact, simple and low-profile structure. The design strategy of high gain Fabry-Perot resonator antennas (FPRA), which have a superstrate with increasing phase in the operating band, has been applied to design the antenna. A double-layered unprinted dielectric superstrate is used as a partially reflective surface (PRS) to enhance the gain of the antenna and to produce a reflection phase curve versus frequency with a positive slope. The superstrate is composed of two dielectric slabs, and it is truncated so that its dimension to be about 1.5λ×1.5λ. By using such an unprinted double-layered dielectric, as a superstrate, the bandwidth of about 14.3% can be achieved. To further increase the size of the upper unprinted slab, the gain can be enhanced, without compromising the bandwidth. A prototype antenna has been designed and simulated at 9 GHz. The achieved peak gain is 17 dB.

Gain enhancement of a wide slot antenna over a wide frequency band using a low profile, second order bandpass frequency selective surface (FSS) as a superstrate is presented in this paper. The proposed multilayered FSS with non-resonant unit cells in each layer allows in-phase transmission of waves radiated from the antenna over a 3dB bandwidth of about 50%. The design allows an enhancement of upto 4dBi in the antenna gain over the entire frequency band (5-8GHz) of operation. The FSS provides a very low insertion loss between the two transmission poles along with a linearly decreasing transmission phase over the band. The composite structure shows an impedance bandwidth (-10dB) of 65% with an average gain between 6-8dBi over the frequency band with a peak gain of 9dBi. Measurement results of the fabricated prototype matches well with the predicted values.

A high-gain rectangular waveguide-fed aperture antenna that uses a Spidron fractal structure to produce circular polarization is proposed. The antenna consists of a Spidron fractal aperture etched onto the ground plane of a dielectric substrate that is directly excited by a WR (Waveguide Rectangular)-90 waveguide-to-coax adapter. A superstrate was implemented at an appropriate distance above the antenna to enhance the broadside gain significantly. An antenna prototype was fabricated and tested to validate the design. The measured impedance bandwidth for | S 11 | ≤ −10 dB is 9.89⁻11.58 GHz (15.74%). The corresponding measured 3 dB axial ratio (AR) bandwidth is 10.68⁻11.00 GHz (2.95%), and within the measured 3 dB AR bandwidth, a maximum realized gain of 9.59 dBic is achieved. The radiation patterns of the proposed antenna are presented and discussed.

The effect of a protecting dielectric superstrate on the resonance of a high Tc superconducting microstrip patch is investigated. The analysis approach is based on the spectral-domain method of moments in conjunction with the complex resistive boundary condition. The complex surface impedance of the superconducting thin film is determined using London’s equation and the two-fluid model of Gorter and Casimir. Numerical results show that the resonant frequency of the high Tc superconducting rectangular patch decreases monotonically with increasing superstrate thickness, the decrease being greater for high permittivity loading.

Abstract A wide band EBG resonator antenna with two layer of dielectric superstrates of the same material is design which is operating in X band. The EBG superstrates act as Partially Reflective Surfaces (PRS) having positive reflection phase curve which are suspended above a double sided dipole patch antenna fed by a coaxial cable pass through ground plane. Thus a resonator cavity is constructed which increases the bandwidth and gain of the feed antenna. The measured results validate the simulation results obtain from Computer Simulation Technology (CST) microwave studio. These results show that the antenna posses a 3 dB gain bandwidth from 8.5 GHz to 11.2 GHz, with a peak gain of 15.3 dBi. Furthermore, the scattering parameter S11 is well within range from 8.6 GHz to 11 GHz.