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An efficient multifunctional metasurface for cross and circular polarization conversion is presented in this letter. The metasurface acts not only as an efficient polarization converter for linearly polarized wave over frequency bands of 5.3–5.4, 7.2–8, and 12.3–13.76 GHz but also perfectly converts linearly polarized wave into circularly polarized wave over multiple bands of 5.1–5.2, 5.6–6.85, 8.8–11.2, and 14.9–20.2 GHz. The behavior of the metasurface is quite stable under oblique incidence for certain bands up to 75°. The broadband circular- polarization conversion, compactness, angular stability, and multiple functionality make it a strong candidate for many applications in the strategic C -, X -, Ku -, and K -bands.

A dual-band UHF/industrial, scientific and medical (ISM) compact rectenna with wideband UHF matching (855–935 MHz) covering all, EU, U.S., and Chinese UHF radio frequency identification (RFID), standards is presented. The proposed design consists of a compact single-port, dual-band antenna, a three-port dual-branch matching network, and two voltage doubler rectifiers implemented with Schottky diodes and terminated with a common 10 $\text{k}\Omega $ load. For each band, the measured RF-to-dc efficiency is around 60% for a −5 dBm unmodulated signal. The wideband behavior of the rectenna supports harvesting of multitone signals. The use of a six-tone signal increases the maximum RF-to-dc efficiency of the dual-band rectifier, from approximately 60% for a single-tone UHF signal (890 MHz) to 80% for a six-tone signal for a received RF power of −5 dBm in both cases. A signal generator is used to generate a six-tone signal of equally weighted and equally spaced (10 MHz separation) monochromatic tones, with a total bandwidth of 50 MHz. The measurement results demonstrate that the dc voltages rectified from the two separate RF signals are effectively superimposed on the load, providing a clear advantage compared to single-band rectennas. The single-layer, compact design with a size of $80\times45$ mm2, with a high RF-to-dc efficiency, is an excellent candidate for wirelessly powered RFID tags.

We present the design and practical implementation of a microstrip diplexer based on the wave discrimination property associated with the electromagnetically induced transparency (EIT)-like effect. The EIT is a quantum interference phenomenon which happens between two atomic transition pathways and allows wave propagation within a medium’s absorption spectrum. Here, we exploit an analogous interference mechanism in a three-port microstrip structure to demonstrate a diplexer based on the EIT-like effect in the microwave regime. Since the transparency is accompanied by a high transmission and strong dispersion characteristics, compact frequency discriminating structures that can resolve nearby frequencies with high isolation can be devised. Our proposed C-band diplexer consists of pairs of unequal open-circuit stubs, which resonate at detuned frequencies and interfere to form the EIT-like passbands for diplexer action. The design is highly compact and scalable in frequency for both PCB and on-chip applications. A prototype of diplexer is fabricated for the center frequencies of lower and upper passbands at 4.6 GHz and 5.5 GHz respectively. The transmission zeros are designed at the complementary channels so that the two passbands are highly isolated presenting the isolation of about 40 dB. The measured insertion loss of lower and upper passband is 0.59 dB and 0.61 dB respectively. Measured input return loss is better than − 15 dB, while the output return losses are well below − 12 dB. Moreover, a decent value of about 200 is achieved for the group refractive index around the EIT-like passbands, which reveals the slow wave characteristics of the proposed EIT-based diplexer.

A circularly polarized monopole antenna fed by coplanar waveguide is presented in this research. The antenna operates in wireless local area network and worldwide interoperability for microwave acc...

A wideband snowflake antenna for 28 GHz millimeter-wave communications is proposed. The antenna has a size of 8×5 mm2, fabricated on ultra-thin 0.254 mm substrate. The antenna consists of four small hexagons surrounding a bigger hexagon in order to attain broadband characteristics. Bandwidth response of the antenna is between 25.28-29.04 GHz (13.43% @ 28 GHz), having 3.12 dBi gain and more than 80% of radiation as well as total efficiency. The antenna specific structure is designed such that it gives dual beam over its entire bandwidth without a noticeable shift in its beam directions. For enhanced gain performance, its 4-element array (of size 32×12 mm2) has been fabricated separately to increase its gain upto 10.12 dBi at 28 GHz. The proposed dual-beam antenna and its array has been modelled on thin Rogers substrate to show that its application in millimeter-wave communication equipment is viable.

A wideband antenna with a high gain and narrow beam-width for future 5G communication systems is presented in this research. The antenna operates in 28 GHz 5G band with a large 35.53% bandwidth ranging from 23.41-33.92 GHz. The array has 4-elements arranged in a linear fashion to attain a high gain of 10.7 dBi. It radiates along its end-fire direction and provides a very narrow beam-width of 14.6° in its H-plane. A corporate feed network specifically designed for thin substrates was used in order to excite the array elements. It is built upon thin 0.254 mm Rogers substrate to minimize transmission losses and attain high radiation efficiencies of more than 90% throughout its operating frequency range. It has a compact structure bearing low cost and is easy to fabricate. This antenna fulfills necessary requirements of 5G communication and is therefore a good candidate to be used in the millimeter-wave range.

We present a single-layer metasurface, which performs both cross and circular polarization conversion at multiple frequency bands. The unit cell of the proposed metasurface consists of periodic array of a uniquely designed hexagonal split ring resonator (SRR). The proposed metasurface behaves as an efficient 90° polarization rotator at dual frequency bands of 6.36-6.59 GHz and 10.54-13.56 GHz. The polarization conversion efficiency approaches 90% within these two operating bands. Moreover, linear-to-circular polarization conversion is also achieved in other three wide frequency bands from 6.10-6.20 GHz, 6.84-9.02 GHz and 14.10-15.48 GHz. The novel features of the subject hexagonal metasurface, which qualify it for numerous practical applications are high cross-polarization conversion (CPC) efficiency, wideband operation and angular stability for oblique incidence up to 45°.

A double-rhomboid bowtie-slot on-chip antenna aided by a back-to-back E-shaped electromagnetic bandgap (EBG) surface for gain enhancement at W-band is presented. The specific structure of both the antenna and the EBG surface is being reported for the first time in an on-chip implementation. The antenna is analyzed independently as well as backed by different electromagnetic bandgap reflective surfaces using standard 0.13 $\mu$ m BiCMOS process. The proposed EBG surface provides a measured gain enhancement of 2 and 8 dB when used as a frequency selective surface and as an artificial magnetic conductor, respectively. With an overall chip size of 1 $ {}\times {\text{1 mm}}^{2}$ , the on-chip antenna demonstrates a $-$ 6 dB impedance bandwidth from 75–100 GHz and an effective gain bandwidth from 80–90 GHz with a peak measured gain of $-$ 0.58 dBi at 84 GHz. The antenna has the smallest reported size and the highest gain in W-band with artificial magnetic conductor as reflective surface.

Two-dimensional metamaterials, consisting of an array of ultrathin building blocks, offer a versatile and compact platform for tailoring the properties of the electromagnetic waves. Such flat metasurfaces provide a unique solution to circumvent the limitations imposed by their three-dimensional counterparts. Albeit several successful demonstrations of metasurfaces have been presented in the visible, infrared, and terahertz regimes, etc., there is hardly any demonstration for ultraviolet wavelengths due to the unavailability of the appropriate lossless materials. Here, we present diamond as an ultra-low loss material for the near and deep ultraviolet (UV) light and engineer diamond step-index nanowaveguides (DSINs) to achieve full control over the phase and amplitude of the incident wave. A comprehensive analytical solution of step-index nanowaveguides (supported by the numerical study) is provided to describe the underlying mechanism of such controlled wavefront shaping. Due to the ultra-low loss nature of diamond in near and deep UV regimes, our DSINs and metasurfaces designed (from them) exhibit a decent efficiency of ≈ 84% over the entire spectrum of interest. To verify this high efficiency and absolute control over wavefront, we have designed polarization-insensitive meta-holograms through optimized DSINs for operational wavelength λ = 250 nm.

This paper presents a planar wideband antenna for future 5G millimeter-wave communication. The antenna structure consists of a Tri-Cell network of hexagonal rings backed up by pseudo-pyramidal patches for improved impedance bandwidth. It operates in 26.677-29.601 GHz spectrum that covers the most famous 28 GHz 5G band. The antenna has an excellent radiation efficiency performance of more than 90% throughout its operating band. It has a good gain of 4.81 dBi suitable for millimeter-wave propagation. It has simple planar structure which is easy to fabricate and demands low cost. Its attractive features such as wide band, high gain, low profile and simple construct makes it quite suitable for use in the upcoming future 5G communication systems.

A wide band antenna working in the 28 GHz 5G designated band has been presented in this paper. It has a semicircular structure backed up by a network of small hexagonal parasitic patch on the backside. It is fed through a coplanar waveguide (CPW) and has a small footprint of $9\times 7.38 \ \mathrm{mm}^{2}$ . It has 3.75 GHz of bandwidth ranging from 27 to 30.76 GHz. It is low loss with radiation efficiencies exceeding 95%. It also exhibits a large gain performance of 5.67 dBi at 28 GHz. The antenna has attractive features that will interest 5G system developers due to its small form factor, low cost, wideband and high gain performance.

This paper presents a Chip-Less RFID tag working in 2–14 GHz. The tag consists of a hexagonal patch surrounded by multiple closed loop hexagonal rings. The tag generates 5 low-point RCS signatures within the operating band resulting in a 12-bit sequence code. Complementary bits are separated by 25 dB RCS transitions indicating a satisfactory code resolution capability. The overall tag dimension is $2.5\times 2.5\mathrm{cm}^{2}$ and a code density of 1.76 bits/cm2. Due to the tag's ability to store a long bit-sequence code, it can be a good candidate for use in various different RFID applications.

This paper presents a compact and cost effective chip-less RFID tag (CRFID) to be operated in 4–14 GHz band. The tag has circular and diagonal closed loop rings for generating multiple resonances to encode a 12-bit sequence. It has a size of $\mathbf{1.4}\times\mathbf{1.4\ cm}^{\mathbf{2}}$ and code density of 6.122 bits/cm2. The proposed tag is modeled upon low cost FR4 substrate and has a planar construct. Due to its attractive features such as long bit-encoding capability, compact size and ease of fabrication, this CRFID is deemed quite suitable to be used in various RFID application scenarios in Internet of Things.

A monopole antenna inspired from Rotman Lens is presented in this paper. It is designed to operate in the unlicensed 60 GHz millimeter-wave band from 54.318-64.477 GHz. It also has a high gain of 5.25 dBi, suitable for millimeter-wave communication. It has more than 90% of radiation efficiency due to the use of Rogers 5880 low loss substrate. It has dual beam radiation pattern in azimuth plan and back radiations are less than −10 dB. The antennas overall dimensions are $5\times 4.5\ \text{mm}^{4}$ , ensuring small form factor. It has a planar structure and along with its other attractive features such as high gain, large bandwidth and dual beam, is deemed quite suitable for future 5G, millimeter-wave communication in the unlicensed 60 GHz band as well as indoor communications.

We demonstrate transmission-based all-dielectric, highly efficient (≈73.4%) and polarization-insensitive meta-axicons (for the visible wavelength of 633 nm) to generate zero and higher order Bessel beams without using additional components. The Bessel beams, owing to their diverse applications and non-diffractive properties, attract great interest from the scientific community. It is shown that the propagation length can be increased through a lower numerical aperture (∼2600 λ for NA = 0.1) whereas a higher full width at half maximum (

A very compact and small sized 2-element planar Ultra Wide band (UWB) antenna having high isolation with band rejection characteristics designed on a FR4 substrate (23 × 26 × 0.8 mm3) is presented in this paper. Each antenna element have a rectangular stepped-slot and a z-shaped slot, both etched in ground plane. The rectangular slot, proximity fed by a 50 Ω micro-strip transmission line, acts as a main radiator while z-shaped slot acts as a filter for rejecting the full WLAN band (5.15-5.85 GHz). Use of an inverted T-shaped slot near top end of ground plane improves isolation more than 24.5 dB in lower UWB band i.e. 3-5 GHz, while the rectangular vertical slot etched at center of the ground plane near the bottom edge reduces the mutual coupling at lower as well as at higher UWB band i.e. 5 - 10.6 GHz. Both measured and simulated results are presented which are found generally in good agreement.

A reflective metasurface exhibiting both cross-polarization conversion (CPC) and linear-to-circular polarization (LP-to-CP) conversion is presented in this paper. The proposed metasurface is composed of 45° tilted T-shaped unit cell having a circular ring at its center. The proposed metasurface converts linearly-polarized wave into its orthogonal counterpart over two frequency bands; 6.2-9.7 GHz, and 15.5-16.5 GHz with more than 90% CPC efficiency. The metasurface also transformed linearly-polarized wave into circularly-polarized wave at frequency bands; 5.6-5.8 GHz and 11.5-14.5 GHz. The metasurface is insensitive to incident angles up to 30° for both CPC and LP-to-CP conversion.

This paper presents design of an hp-shaped reconfigurable antenna printed on a 1.6 mm thicker FR-4 substrate. The antenna works in four distinct modes frequency modes, contingent on the status of the two switches. Six resonant bands are obtained by the antenna, i.e. 1.8 GHz (GSM1800), 2.10 (3G LTE-advanced), 3.15 GHz (Radiolocation), 3.50 GHz (WiMAX), 3.88 GHz (Fixed satellite services) and 5.56 GHz (WLAN). The antenna gives optimum performance in terms of gain (1.84–3.22 dB), bandwidth (180–1020 MHz) and radiation efficiency (91–95%) in these six frequency bands. The antenna is properly matched in all these bands (VSWR

This paper presents a dual-band coplanar waveguide (CPW) fed printed antenna with rectangular shape design blocks having ultrawideband characteristics, proposed and implemented on an FR4 substrate. The size of the proposed antenna is just 25 mm × 35 mm. A novel rounded corners technique is used to enhance not only the impedance bandwidth but also the gain of the antenna. The proposed antenna design covers two ultrawide bands which include 1.1–2.7 GHz and 3.15–3.65 GHz, thus covering 2.4 GHz Bluetooth/Wi-Fi band and most of the bands of 3G, 4G, and a future expected 5G band, that is, 3.4–3.6 GHz. Being a very low-profile antenna makes it very suitable for the future 5G Internet of Things (IoT) portable applications. A step-by-step design process is carried out to obtain an optimized design for good impedance matching in the two bands. The current densities and the reflection coefficients at different stages of the design process are plotted and discussed to get a good insight into the final proposed antenna design. This antenna exhibits stable radiation patterns on both planes, having low cross polarization and low back lobes with a maximum gain of 8.9 dB. The measurements are found to be in good accordance with the simulated results.

Metasurfaces, two dimensional (2D) metamaterials comprised of subwavelength features, can be used to tailor the amplitude, phase and polarisation of an incident electromagnetic wave propagating at an interface. Though many novel metasurfaces have been explored, the hunt for cost-effective, highly efficient, low-loss and polarisation insensitive applications is ongoing. In this work, we utilise an efficient and cost-effective dielectric material, hydrogenated amorphous silicon (a-Si:H), to create a ultra-thin transmissive surface that simultaneously controls phase. This material exhibits significantly lower absorption in the visible regime compared to standard amorphous silicon, making it an ideal candidate for various on-chip applications. Our proposed design, which works on the principle of index waveguiding, integrates two distinct phase profiles, that of a lens and of a helical beam, and is versatile due to its polarisation-insensitivity. We show how this metasurface can lead to highly concentrated optical vortices in the visible domain, whose focused ring-shaped profiles carry orbital angular momentum at the miniaturised scale.

In this paper two triple-band monopole antennas are proposed for portable wireless applications such as WiFi, WiMAX and WLAN. Two different geometrical structures are used for the radiating elements of these antennas, each printed on a low cost FR-4 substrate. Truncated metallic copper ground is used to attain optimum radiation pattern and better radiation efficiency. The frequency of the antennas is reconfigured using a lumped-element switch. The proposed antennas covers three frequency bands 2.45, 3.50 and 5.20 GHz depending upon the switching conditions. Both antennas works with an optimum gain (1.7–3.4 dB), bandwidth (6–35%), VSWR (

Recent surge in the development of wireless communication has increased the need of the antennas that can operate at more than one frequency band. To meet the requirements, reconfigurable antennas are used. This paper presents design and analysis of a low profile, planar and, frequency reconfigurable E-shape patch antenna, using a 1.6 mm thicker FR-4 substrate. The antenna operates in two single-band and two dual-band modes, depending on the status of the two switches. The proposed antenna works efficiently (>90%) with an adequate gain (>2 dBi) and bandwidth (430 MHz–1 GHz) in the desired frequency bands {WiFi (2.45 GHz), WiMAX (3.59 GHz), WLAN (5.2 GHz), Military/NATO (4.5 GHz), C-Band (6.22 and 6.27 GHz)}. The antenna is optimally matched (VSWR < 1.45) in all these six frequency bands. The proposed antenna is compact in size (40 × 35 mm2) and can be used in portable electronic devices to support multiple wireless services. The antenna is analysed in computer simulation technology, microwave stud...

This paper presents a novel compact unilayer frequency selective surface (FSS) for ultra-wideband (UWB) applications particularly for gain enhancement of printed antennas. The proposed FSS unit cell consists of simple metallic patterns printed on both sides of 14 mm × 14 mm FR4 substrate. The proposed FSS has very low transmission co-efficient and linearly decreasing reflection phase over the bandwidth of 9 GHz in 3–12 GHz range, which makes it suitable candidate to provide in-phase reflection for UWB antennas. For the validation of gain-enhancement capability, the FSS is paired with a general monopole UWB antenna demonstrating an average gain improvement of 4 dB. The antenna composite has a maximum gain of 8.9 dBi.

This paper presents the design of a tri-band flower-shaped planar monopole antenna operating at three frequencies i.e. 1.576 (GPS), 2.668, and 3.636 GHz (Mobile WiMAX). The radiating element of the antenna is backed by a 1.6 mm thicker FR-4 substrate having a dielectric constant of 4.3. The substrate is backed by a truncated ground plane. The antenna is fed through a 50 Ω microstrip line. The flower shape of the radiating element is derived from the basic circular shape by introducing in it rounded slots of various radii. The upper part of the antenna is flower shaped while the lower part comprises a microstrip feed line and two branches, each having two “leaves” at the end. The leaves and branches contribute in the impedance matching of the lower (1.576 GHz) and middle (2.668 GHz) frequency bands. The antenna gives an acceptable simulated efficiency >70% in the three frequency bands. Suitable gains of 1.63, 2.59, and 3.23 dB are obtained at 1.576, 2.668, and 3.636 GHz, respectively. The antenna m...

In this paper, a reflective metasurface working as an efficient cross-polarizer as well as absorber in microwave frequency regime is presented. The proposed metasurface is composed of a metallic split-ring resonator (SRR) along with four orthogonally placed stubs with it. The surface transforms linearly-polarized wave into its cross-counterpart over three operating bands; 3.4-3.6 GHz, 5.3-5.4 GHz, and 10.5-10.9 GHz. The achieved polarization conversion ratio (PCR) is above 60% within the operating frequency bands. The surface also acts as an absorber for normally incident wave over another frequency band 16.9-17.2 GHz.

A novel metasurface with half-mirror (1:1 beam-splitter) and quarter-wave plate operation is being presented in this paper. The design consists of a square-shaped slot resonator with a slit and a split ring resonator inside it. The proposed metasurface exhibits simultaneous half-mirror and quarter-wave plate (QWP) operation over two broad frequency bands between 7.025-7.385 and 19.1-20.33 GHz, while only half-mirror operation is achieved over other two frequency bands centered at 14.6-16 and 27.7-29 GHz.

A dual broadband polarization conversion metasurface is presented in this paper. The metasurface is composed of periodic unit cells, each unit cell consists of a square-shaped resonator having three slits inside it. The surface efficiently transforms an incident linearly polarized electromagnetic (EM) wave into its cross component within the frequency bands of 7.4–10.5 GHz and 12.7–20 GHz. With its dual band operation on a single layer FR4 dielectric substrate, the subject metasurface is a good contender in the field of cross-polarization conversion metasurfaces.

In this communication, a broadband reflective 90° polarization rotator metasurface is presented. The metasurface unit cell is composed of double-slit circular split ring resonator with a Swiss-cross in the middle. A horizontally-polarized normally incident wave is rotated by this metasurface into vertically-polarized wave and vice versa within 3dB fractional bandwidth of 66.6% from 5.7–11.4 GHz. The polarization conversion ratio (PCR) of the proposed polarization rotator is above 75% within the operating band. A broadband polarization rotation is realized because of multiple plasmon resonances at different frequencies.

A dual broadband polarization conversion metasurface is presented in this paper. The metasurface is composed of periodic unit cells, each unit cell consists of a square-shaped resonator having three slits inside it. The surface efficiently transforms an incident linearly polarized electromagnetic (EM) wave into its cross component within the frequency bands of 7.4-10.5 GHz and 12.7-20 GHz. With its dual band operation on a single layer FR4 dielectric substrate, the subject metasurface is a good contender in the field of cross-polarization conversion metasurfaces.

A reflective broadband cross polarization conversion (CPC) metasurface operating in microwave frequency regime is simulated and presented in this paper. The metasurface is a periodic arrangement of unit cells and each unit cell consists of a metallic circular split ring resonator (C-SRR) with a circular loop inside it. A linearly-polarized or circularly polarized wave is transformed into its orthogonal counterpart when reflected back from the metasurface. Four plasmonic resonances at different frequencies is the reason behind broadband CPC operation achieving 3dB fractional bandwidth of 107% from 4.2-13.9 GHz. The proposed design has the highest reported 3dB fractional bandwidth made on a lossy single layer FR4 substrate for normal incidence. The designed metasurface is useful in manifold practical applications for polarization control devices.

In this communication, a broadband reflective 90° polarization rotator metasurface is presented. The metasurface unit cell is composed of double-slit circular split ring resonator with a Swiss-cross in the middle. A horizontally-polarized normally incident wave is rotated by this metasurface into vertically-polarized wave and vice versa within 3dB fractional bandwidth of 66.6% from 5.7-11.4 GHz. The polarization conversion ratio (PCR) of the proposed polarization rotator is above 75% within the operating band. A broadband polarization rotation is realized because of multiple plasmon resonances at different frequencies.

A 5G ultra-wideband monopole antenna working in millimeter-wave spectrum is being proposed here. Operating band of the antenna is 24.42-40.29 GHz exhibiting an enormous bandwidth of 15.87 GHz. The bandwidth coverage has been achieved by structuring the antenna through a unique method of pentagon filling. Low loss 0.254 mm thick Rogers substrate was used to attain radiation efficiency of more than 95% and a peak gain of 4.86 dBi. The antenna is compact in size with dimensions of 8×7 mm2. The proposed antenna is deemed suitable for future 5G and millimeter-wave communications due to its attractive characteristics.

A broadband electromagnetic beam-splitting metasurface is designed and presented in this paper. This metasurface is composed of two metallic E-shaped patches modeled on FR4 dielectric substrate. The electromagnetic wave when normally incident on the proposed metasurface, it is split into two waves; half of the energy is reflected and the other half is transmitted. Owing to asymmetric nature of the metasurface along x and y-axis, the beam splitting is achieved at 13 GHz for x and at 8 GHz for y polarized wave.

An ultra-wideband (UWB) log-periodic dipole array (LPDA) antenna inkjet-printed on a 0.5 mm thick photo paper substrate is presented. The overall size of the LPDA antenna is 130 × 60 mm2. The LPDA antenna exhibits stable input-impedance characteristics and a consistent end-fire radiation pattern over the whole operating band of 2.2–11 GHz. Fulfilling the need of high-gain flexible antennas for UWB, a highly directive measured gain of 9.5 dBi on a paper substrate makes it an excellent candidate for flexible wireless devices.

A compact uniplanar dual wideband antenna for tablet computers is presented. The proposed antenna provides full coverage of LTE700/2300/2500, GSM850/900/1800/1900, UMTS2100, Bluetooth, and 2.4-GHz WLAN bands with a very small foot print 30 × 10 mm2. The antenna has uniplanar structure and is easy to fabricate on single side of 0.8-mm thick FR4 substrate. This is achieved through three optimized strips: a feeding strip, an inductively coupled inverted L-shaped strip, and a shorted strip embedded with SMT components. The proposed design supports more than eight operating bands in 3:1 VSWR standard, exhibiting positive gains over all nine bands of operation and 80%-90% radiation efficiency in the higher LTE and WWAN bands. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:496-502, 2016.

In recent research published by Chetan et al. [J. Appl. Phys. 126, 175104 (2019)], a wideband metamaterial absorber for Ku and K band applications was presented. In this article, the electromagnetic absorption of more than 90% has been claimed over a large band of frequencies from 14.44 GHz to 27.87 GHz, achieving a bandwidth of 13.43 GHz. In this comment paper, we proved that the authors did not consider the cross-polarized component of the reflected wave while calculating the absorption index of the proposed structure. The structure, in practical, absorbs even less than 20% of the incident electromagnetic energy within the claimed band while the other energy is reflected back in the form of 90° rotating electric field with respect to the incident field. The subject metamaterial “absorber” can be seen as an efficient cross-polarizer having a polarization conversion ratio above 95%.

We present a quasi-crystal metasurface that can simultaneously work as efficient cross-polarizer and circular polarizer for wide range of frequencies. The quasi-crystal technique benefits from individual resonant response of anisotropic patch and the coupled response due to periodic perturbations in the square lattice. It is shown that quasi-crystals offer broadband response for cross-polarization as well as high efficiency circular-polarization conversion of reflected fields. The quasi-crystal metasurface achieves cross-polarization (above −3 dB) for two broad frequency bands between 10.28–15.50 GHz and 16.21–18.80 GHz. Furthermore, the proposed metasurface can simultaneously work as high efficiency circular-polarizer from 10.15–10.27 GHz and 15.51–16.20 GHz. The metasurface design is also optimized to suppress co-polarization below −10 dB between 10.5–15.5 GHz. This metasurface can find potential applications in reflector antennas, imaging microscopy, remote sensing, and control of radar cross-section etc.

This paper presents lumped element manifestation of the quantum phenomenon known as Electromagnetically Induced Transparency (EIT). The EIT effect is reproduced at microwave frequencies by exploiting the interference effects of two series-RLC resonators that load a microstrip line in shunt configuration. The compact EIT-based devices can be employed in various microwave applications such as tunable filtering, phase shifting and material sensing. The proposed design provides the quality factor of 22, insertion loss of less than 1. SdB and 3dB bandwidth of 43 MHz.

In this paper, a broadband linear-to-circular (LTC) polarization conversion anisotropic metasurface is simulated and investigated. The unit cell of the proposed metasurface contains an outer C-shaped ring with a metallic circular patch in the center. A linearly polarized normally incident wave is converted into circularly polarized reflected wave for 3dB axial ratio (AR) in the frequency range of 15.26-18.70GHz. Moreover, LTC polarization conversion efficiency is above 90% within the frequency band of 16-18GHz. The designed metasurface has potential applications in polarization control microwave devices.

An electrically small antenna for future 5G millimeter-wave applications is presented. The proposed antenna has a size of 4×4 mm2, The antenna is semi-circular in shape with an arc slot, resulting in a broadband characteristic. The proposed antenna has a wide impedance bandwidth that ranges from 23 to 37 GHz. The antenna has a maximum absolute gain of 3.44 dBi and is more than 89% efficient. The length of any side is less than 0.49λ 0 at 23 GHz, making it extremely useful for array configuration deployment. Modelled on thin Rogers substrate with attractive characteristics and low-cost fabrication requirements, this antenna becomes an excellent candidate for future 5G communications.

A novel broadband substrate integrated waveguide (SIW) antenna is designed at V-band (60 GHz) for high gain 5G applications. The antenna consists of a truncated square patch having tiny square slots along upper and lower edge of the patch. The antenna size is 5.2×5.2 mm2. By putting via-through-holes along the four sides of the truncated patch, an SIW cavity is achieved. This cavity helps to obtain a wide impedance bandwidth and high gain by suppressing the surface waves. The impedance bandwidth of the proposed antenna is 15% (56.2-65.2 GHz) and simulated peak gain of 7.76 dBi is achieved.

This paper presents a circularly polarized (CP) monopole antenna for satellite applications. The antenna consists of two C-shaped monopole radiators and has an overall compact size of 32 × 25 mnr2. The two C-shaped monopole radiators along with L-shaped slot in the ground plane are mainly responsible to achieve circular polarization. The antenna is fabricated and tested. The measured results are in quite good agreement with simulations. The measured impedance bandwidth of 1170 MHz (5.5 - 6.67 GHz) and axial ratio bandwidth of 760 MHz (5.91 - 6.67 GHz) is achieved.

This paper presents a logarithmic spiral antenna for 5G 28 GHz band. The antenna has 3.982 GHz of impedance bandwidth ranging from 26.396 − 30.378 GHz. The antenna has directional characteristics with gain of 5.36 dBi and radiation efficiency greater than 94 %The antenna is modelled upon Rogers substrate suitable for low-cost PCB fabrication. The proposed antenna has physical size of 6×4.5mm2 and an electrical size of 0.54λ 0 x0.41λ 0 at 28 GHz. The proposed antenna has wide bandwidth, high gain and small size making it a natural choice for future 5G mobile applications.

This paper presents a dual passband frequency selective surface for future 5G communications. The FSS has two ring slots with hexagonal shape, one of which has been applied with a fractal generator. The FSS unit cell is 3.7×3.7mm2. The pass band ranges are 27.639 - 28.997 GHz and 37.442 - 41.452 GHz, covering both 28 and 38 GHz 5G bands. The FSS has been modelled using very thin 0.127 mm flexible Rogers substrate. The dual band response, low cost and unique design makes this FSS suitable for EMI shielding as well as radome applications for future 5G and millimeter-wave communication systems.

This paper presents a dual-band antenna for future fifth generation (5G) wireless communication systems. The antenna operates in 26.98 − 29.81 and 34.29 − 42.20 GHz frequency bands, covering standard 28 and 38 GHz 5G bands. The structure consists of hexagonal split ring resonator (SRR) and a closed ring resonator (CRR). The proposed antenna is modelled upon 0.254 mm thick Rogers substrate and has a low profile of 6×8 mm2, It has a peak gain of 4.63 dBi with more than 80% radiation efficiency throughout its operating range. The proposed antenna has 2.83 and 7.92 GHz bandwidth at 28 and 38 GHz respectively.

In this letter, a 28.5-bit chipless RFID tag, based on paper substrate and realized using inkjet printing technique is presented. Operating within ultrawideband, the tag occupies a compact size of 2 ×4 cm 2 . Focusing on applications requiring time and date identification, a novel encoding technique is presented that allows efficient frequency band allocation based on the number of required instances of time and date variables. A figure of merit (FOM) relating coding capacity and tag dimensions coined as code density is also introduced. A systematic design process followed by simulations and verified through measurements reveal a high code density of 3.56 bits/cm 2 for the presented chipless tag.