Patch Array Research Articles

Anisotropic absorber and tunable source of MIR radiation based on a black phosphorus-SiC metasurface

We propose a black phosphorus-silicon carbide (BP-SiC) metasurface with in-plane structural symmetry that can act as both a nearly perfect anisotropic absorber and tunable polarized source of mid-infrared (MIR) radiation. The metasurface is a periodic array of square SiC patches integrated with a BP flake at the top and separated from a bottom reflector by a BaF2 spacer. We first use analytical calculations and numerical simulations to study the hybridization of the anisotropic plasmons of BP with isotropic phonons of SiC. We also analyze the in-plane characteristics of the resulting hybrid modes of the BP/SiC heterostructure and the BP-SiC metasurface. It is then demonstrated that the proposed metasurface can serve as a nearly perfect anisotropic absorber of MIR radiation with highly selective and omnidirectional features. It is also shown that the metasurface can be used as a polarized MIR source with tunable temperature, which is determined by the thermal equilibrium between the matter and radiation. The suggested design holds promise for artificial coatings that can tune the blackbody thermal signatures, MIR sensing, and highly directional in-plane transportation of the MIR energy.

Coupled Solid and Inverse Antenna Stacks Above Metal Ground as Metamaterial Perfect Electromagnetic Wave Absorbers with Extreme Subwavelength Thicknesses

AbstractThe ability to completely absorb an electromagnetic (EM) wave with a material much thinner than the wavelength is a prerequisite for achieving ultracompact, flexible, and lightweight EM devices. Herein, a metamaterial microwave perfect absorber is demonstrated as thin as 1/1250 of the target wavelength by coupling an array of metal patches to inverse cross metal antennas through a dielectric separator and with a reflector placed underneath. Compared to a conventional three‐layer absorber, the modified design reduces the resonance frequency by up to tenfolds without altering the patch and dielectric layers, but by reconfiguring the induced current pathways that reorient the dipolar magnetic fields and dramatically boost the magnetic flux. With the reflector, the stack is framed for perfect absorption at the critical coupling condition, which is identified by monitoring the reflection phase shift across the resonance frequency. The study provides guidelines for shrinking the thickness further and can be extended to other frequencies.

Design and Integration of Millimeter-Wave 5G and WLAN Antennas in Perfect Full-Screen Display Smartphones

Smartphone industries are seeking to maximize screen size, but a perfect full-screen phone is not yet available due to the unoccupied area required for the mobile antennas. Since a touchscreen is coated with transparent conductive layers, antennas below the touchscreen cannot create outward radiation. Accordingly, a non-metallic area is left for the antennas, which reduces the screen size. In this paper, we propose a design and integration of antennas for future millimeter-wave 5G smartphones to suit a perfect full-screen display. The proposed design consists of three modules, including a 1 × 12 patch antenna array at 28 GHz, a 1 × 8 patch array at 38 GHz, and a loop antenna at 2.45 GHz. The design environment consists of fully metallic top and bottom enclosures, mimicking the touchscreen and the printed circuit board, respectively. The three antennas were implemented on the flanks. Although the design area was limited and contained in parallel conductive plates, the three antennas still provided broad impedance bandwidths (26.5–32.0 GHz, 35.2–42.0 GHz, and 2.41–2.48 GHz) and high gains (16.7 dBi, 16.4 dBi, and 4.3 dBi). The isolation was larger than 20 dB, and the scanning ranges were ±45°. The proposed scheme is the first antenna system designed for perfect full-screen display phones.

Performance Enhancements of Fully Inkjet-Printing Technology for Antenna-in-Package and Substrate Integrated Waveguides

A fully inkjet-printing technology is applied to antenna-in-package (AiP) and substrate integrated waveguide (SIW) to enhance the performance of three components, including via holes, wire bonding, and flexible antenna arrays. First of all, earlier studies utilize shorting pins for the conductive pathway in high-density AiP and SIW, but this requires an additional procedure to plate the conductor. We propose a mechanical approach to form a cylindrical hole, plating the surface with silver nanoparticles and realizing the equivalent circuit model of the shorting pin. The proposed approach does not require high alignment sensitivity or the precise control of laser power level. Second, fully inkjet-printed wire bonding is proposed for the system on the package. The proposed technique not only reduces the discontinuity but also enables a fabrication without additional assembly. Third, the proposed technique is implemented for antenna development, which shows desirable performance with reduced fabrication complexity. The proposed technology is validated by microstrip lines, SIWs, SIW cavity slots, and flexible 4 × 4 patch arrays fabricated on various substrates including RO 4003C, polyimide, and polyethylene naphthalate. For comparison purposes, conventional approaches using printed circuit boards are also implemented and tested. The results indicate the generality and capability of the proposed technique.

Flow dynamics in lateral vegetation cavities constructed by an array of emergent vegetation patches along the open-channel bank

The hydrodynamics in a straight rectangular open channel containing novel lateral cavities constructed by an array of square emergent vegetation patches discontinuously distributed along the bank were explored numerically using three-dimensional large eddy simulations (LES). Five vegetation densities (Φ), ranging from 0.02 to 0.25, as well as the traditional lateral cavities created by impermeable solid media, were tested. The effects of the cavity aspect ratio (AR) were also examined. The LES results showed that the mean recirculation pattern inside the vegetation cavities and coherent structures in the horizontal shear layer were closely dependent on Φ and AR. When Φ ≥ 0.06, a main recirculation vortex that formed inside the vegetation cavities resembled that within solid media cavities, whereas the extent of the former increased upstream as Φ increased. Compared with the solid cases, the vegetation cavities exhibited a higher turbulent intensity within the shear layer and wider regions of enhanced turbulent kinetic energy, which decreased with increasing Φ. The penetration depth of the elevated turbulent kinetic energy into the cavities also decreased with increasing Φ, whereas a deeper penetration was expected at larger AR values. The interfacial turbulence was dominated by “cavities field”-scale coherent vortices at Φ ≤ 0.06, whereas “cavity element”-scale at Φ ≥ 0.15. When Φ = 0.1, the shear vortices of both scales contributed to the enhancement of the interfacial turbulence. The mean mass exchange showed a non-monotonic relationship with Φ and reached maximum values at Φ = 1. The total momentum transport efficiency decreased monotonically with increasing Φ. Despite the AR and Φ values, the turbulent motions dominated the momentum transport over most of the cavity length.

Series Fed Designs of Planar Circular and Hexagonal Microstrip Antenna Arrays for High Gain and Reduced First Side Lobe Level Radiation

To achieve a high gain and low first side-lobe level, variants of linear and planar series fed circular and hexagonal microstrip antenna arrays using the binomial distribution, are proposed around 3000 MHz frequency band, on thinner Arlon substrate (h ~ 0.027λg). The linear 7 × 1 array of circular patches, yields first side-lobe level of −25 dB with a gain of 12.7 dBi, whereas using hexagonal patches, respective values are, −28 dB and 12.9 dBi. The planar 5 × 3 and 5 × 5 arrays using half wavelength and wavelength spacing are presented. An optimum response is obtained in 5 × 5 array for the wavelength inter-element spacing. Here, using circular patches, first side lobe level in the E and H-planes is −29 and −14 dB, respectively, with a peak gain of 17.6 dBi, whereas that using hexagonal patches, the respective first side lobe level in the E and H-planes is −26 and −17 dB, with a peak broadside gain of nearly 19 dBi. Thus using a thinner substrate, proposed series feed binomial planar arrays offer a gain of more than 15 dBi with a lower first side lobe level.

High gain and broadband circularly polarized antenna using metasurface and CPW fed L-shaped aperture

A high gain and broadband circularly polarized antenna is designed with a single planar layer substrate. To realize a broadband antenna initially, a circular patch antenna is fed by a slot with a coplanar feed line in the ground plane. A metasurface is designed to consist of a 3 × 3 array of circle patches with the circular patch antenna at the center of the array. Moreover, the slot is also modified into L-shape to generate circular polarization. In addition, stubs are introduced in the slot to improve the impedance bandwidth. As a result, the circular patch metasurface has improved the impedance bandwidth, axial ratio bandwidth and gain. Due to the above-mentioned combinations, an impedance bandwidth of 20.18% (4.9–6 GHz) with an axial ratio bandwidth of 16.21% (5.1–6 GHz) is obtained. Furthermore, the antenna has a peak gain of 10.43 dBic which is remarkably very high in single-layered planar antennas.

A 45° Polarized Wideband and Wide-Coverage Patch Antenna Array for Millimeter-Wave Communication

A 45° polarized millimeter-wave (mmWave) patch antenna and arrays with wide impedance and gain bandwidth are proposed in this article. The compact antenna consists of stacked patches, one substrate integrated waveguide (SIW) back cavity, one SIW square cavity, and a feeding line. The patches and the SIW back cavity rotate 45° with respect to the SIW square cavity. For the antenna, the −10 dB impedance bandwidth is from 22.31 to 29.65 GHz, and the peak gain is greater than 5 dBi in the bandwidth from 22 to 30.5 GHz. Based on the proposed antenna, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times16$ </tex-math></inline-formula> linear array is designed, fabricated, and measured. According to the experimental results, all antenna elements can realize the −10 dB impedance bandwidth from 21.7 to 27 GHz. Within 3 dB gain fluctuation, the scanning coverage of the linear array can achieve 116° in the frequency band from 22 to 26 GHz and 110° at 27 GHz. Then, an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times 8$ </tex-math></inline-formula> planar array with wide bandwidth and wide scanning coverage is proposed. The reflection coefficient can achieve less than −10 dB from 21.82 to 27.22 GHz. The main beam of the radiation pattern can be widely spatially scanned. In the bandwidth from 22 to 26 GHz, the scanning coverage within 3 dB gain fluctuation can achieve 107°. Also, at 27 GHz, the coverage can achieve 90°. Due to the outstanding performance, reliable multilayer printed circuit board (PCB) fabrication technology, and easy integration with circuits, the proposed antenna and arrays are good candidates for the fifth-generation (5G) mmWave communication systems, satellite communication systems, and so on.

Research on in‐band stealth of antenna based on phase gradient metasurface

AbstractIn this letter, a low in‐band radar cross section (RCS) antenna with radiation and scattering characteristics based on phase gradient metasurface (PGM) is proposed. The proposed structure consists of periodic arrays of metallic patches printed on a 1.2 mm dielectric substrate with a metallic ground plane, and the RCS is reduced between 7.8 and 12 GHz under normal incidence. Without increasing the structural complexity, some units on the metasurface are used directly as the radiators of the antenna array, which maintains the radiation characteristics of the antenna and reduces its RCS in the working band. The performance test for metasurface antenna agrees well with simulation.

Metasurface-based electromagnetic structure for electromagnetic absorption and radiation application

AbstractIn this paper, a metasurface (MS)-based multi-functional electromagnetic (EM) structure is proposed to realize its two different applications, namely absorption and radiation. The proposed structure is based on periodic arrays of disk-shaped metallic patches and split rings with four embedded lumped resistors. The metallic vias are inserted from top to bottom to connect the disk-shaped patches with a feeding network designed on the bottom layer where two p-i-n switches are embedded in the feeding network to alter the different functions of the proposed structure. For free space incident plan wave, the designed structure works as an absorber when the p-i-n switches are switched OFF. The absorber operates over a frequency band from 6.2 GHz to 8.2 GHz and unchanged over an incident angle from 0° to 30° for both TE and TM polarized incident waves. The same structure also works as a low scattering and high gain radiator when the p-i-n switches are turned ON and radiate within absorbing frequency band, i.e. from 7.5 to 8.0 GHz. The designed structure is fabricated and experimentally verified for EM absorption and radiation applications.

Highly Efficient Dual-Beam Frequency Scanning Based on SSPPs With Parasitic Patch Array

A leaky-wave antenna (LWA) realizes radiation of travelling wave along guiding structures. Periodic modulation is an effective approach to turn non-radiating modes into radiating modes. A high-efficient LWA based on spoof surface plasmon polaritons (SSPPs) loaded with parasitic patch array is proposed. Sinusoidal modulation is used for the radiation of SSPPs, while parasitic array mitigates the open stopband (OSB) effect. A prototype is fabricated and measured. The measured and simulated results agree well with each other. Such design shows wide angle coverage of 83° from backward to forward and stable gain distribution of about 12 dB within the whole operating band.

Dual-port traveling-wave frequency-scanned patch array antenna for E-band vehicle sensing and imaging applications

Dual-port traveling-wave frequency-scanned patch array antenna for E-band vehicle sensing and imaging applications

Simultaneous Decoupling and Decorrelation Scheme of MIMO Arrays

Correlations and mutual couplings in antenna arrays lead to performance deterioration of multiple-input-multiple-output (MIMO) systems. The relation between mutual coupling and correlation is complex, especially in non-isotropic multipath environments. Reducing mutual coupling does not guarantee an eventual reduction of the overall correlation and vice versa. In general, it is not a trivial task to reduce mutual coupling and correlation simultaneously in arbitrary multipath environments. In this correspondence, a planar metamaterial structure (PMS) and an array-antenna decoupling surface (ADS) are applied to the antenna array for simultaneous reductions of correlations and mutual couplings. The PMS comprises regularly arranged metamaterial elements holding certain transmission features. The ADS placed between the PMS and array is a substrate with printed rectangular metal strips. A 1 &#x00D7; 4 patch array is taken as an example to demonstrate the effectiveness of the proposed scheme. According to the simulated and measured results, the combination of PMS and ADS can work together without interfering or affecting the matching condition of the antennas. As a result, the mutual coupling and overall correlation between the antenna elements are reduced in a general multipath environment.

Design and simulation of dual-band rectangular microstrip patch array antenna for millimeter-wave

Microstrip array antennas are essentially for radar and communications systems. They are used to get a needed pattern that cannot be realized with a single element. This paper aims to design and simulate of rectangular microstrip patch array antenna 1 patch (1×1), 2 patches (1×2), and 4 patches (1×4) and improve the performance results. The proposed antenna is simulated by using electromagnetic simulation, computer software technology Microwave studio (CST) printed on Rogers RT5880 (lossy) substrate with dielectric constant 2.2, 0.0009 loss tangent, and thickness 0.1 mm. The simulation results show that the small patch antenna size (1.57 mm × 2 mm) for three designs works at dual bandwidth. The major target of this work is to accomplish an unusual directivity with improved gain for three antenna array designs.

An ultra-broadband flexible polarization-insensitive microwave metamaterial absorber

In this paper, an ultra-broadband flexible polarization-insensitive microwave metamaterial absorber is proposed, characterized, and fabricated. To achieve high broadband absorption, a two-layer periodic indium-tin-oxide (ITO) patches array printed on polyethylene terephthalate (PET) dielectric layers is used to generate high ohmic loss. The simulation results show that the proposed absorber can achieve greater than 90% absorption in the microwave band range of 19.68 to 94.7 GHz. The absorber is polarization-insensitive due to the symmetry of the structure with high absorption over a wide incidence angle of 60°. The mechanism of ultra-broadband absorption is discussed by the impedance matching theory, the surface current distribution, and the electric field distribution. In addition, the equivalent circuit model is utilized to analyze the effect of the structural parameters. Furthermore, the bow-frame method validates that the experimental measurements are consistent with the simulated spectra. With advantages of absorption of ultra-broadband, polarization-insensitivity, and flexibility, the proposed absorber facilitates its use in numerous potential applications for energy harvesting, imaging and sensing, stealth technology, modulating, and so on.

Comparative characterization of microstrip patch antenna array with defected ground structure for biomedical application

In this paper, microstrip dual band antenna array with defected ground structure has been proposed for low frequency wearable on-body applications. The array has been simulated with Cotton, Polyimide, Polyester and Teflon (PTFE) flexible materials which are mostly used for biomedical applications. The performance of 2x2 trapezoidal patch array with partial ground, thin slot defection at center has been studied in terms of return loss, VSWR, power handling capability, radiation pattern and surface current distribution. All substrates exhibits acceptable fractional bandwidth below -10 dB and Cotton proves its superiority than other substrates with -20 dB and -48 dB return loss with 16.12% and 7.73% bandwidth at 1.24 GHz and 1.94 GHz respectively. The proper matching of array has been proved with VSWR value below 1.3 for all substrates. The observation of input port impedance shows that, Cotton array has good impedance matching nearly to 50 Ω and PTFE array has 100 Ω poor impedance matching. The proposed four flexible array exhibit omnidirectional pattern in H plane with 1.43 dBi gain and bidirectional pattern in E plane with 1.4 dBi gain which are support for ideal fitness of proposed flexible material array for medical applications.

Sound Insulation Performance of Composite Double Sandwich Panels with Periodic Arrays of Shunted Piezoelectric Patches.

The existing sandwich structure of the aircraft cabin demonstrates a good sound insulation effect in medium and high frequency bands, but poor in the low frequency band. Therefore, we propose an infinite new lightweight broadband noise control structure and study its sound transmission loss (STL). The structure is an orthogonally rib-stiffened honeycomb double sandwich structure with periodic arrays of shunted piezoelectric patches, and demonstrates lighter mass and better strength than the existing sandwich structure. The structure is equivalent according to Hoff’s equal stiffness theory and the effective medium (EM) method. Using the virtual work principle for a periodic element, two infinite sets of coupled equations are obtained. They are solved by truncating them in a finite range until the solution converges. The correctness and validity of the model are verified by using simulation results and theoretical predictions. Eventually, a further study is performed on the factors influencing the STL. All the results demonstrate that the STL in low-frequency can be improved by the structure, and the sound insulation bandwidth is significantly broadened by adding shunted piezoelectric patches. The structure can provide a new idea for the design of broadband sound insulation.

Wideband series feeding antenna array made of substrate integrated waveguide slot array and patch array

In this paper, a wideband two layer slot array antenna is proposed which operates in the frequency range of 12–14.4 GHz. The lower layer of the antenna array includes narrow rectangular slots and the upper layer consist of rectangular patches shorted on the sides of the patches with via holes. The wideband operation is obtained by making two resonances. One resonance is due to radiation of the single element and the other is the effect of mutual coupling between adjacent elements. An 8 element array is designed, simulated and fabricated with good agreement between simulated and measured results.

A Metasurface-Based Wide-Bandwidth and High-Gain Circularly Polarized Patch Antenna

A metasurface-based circularly polarized (CP) microstrip patch antenna with high performance in terms of the global bandwidth and gain is presented. The antenna configuration was a square-modified microstrip patch that was sandwiched between a metasurface and the ground plane. The metasurface comprised a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \times 4$ </tex-math></inline-formula> array of square patches, while the single-feed radiating microstrip patch had axial ratio (AR) tuning stubs and a crossed slot. Under excitation, the microstrip patch and crossed slot, in conjunction with the metasurface, generated multiple resonances and AR minimum points that combined to produce large global bandwidths with regard to the impedance, AR, and 3 dB gain. Using a stacked layout, a low-profile design with the dimensions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$54\,\,\text {mm} \times 54\,\,\text {mm} \times 3.1$ </tex-math></inline-formula> mm ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2\,\,\lambda _{\text {o}} \times 1.2\,\,\lambda _{\text {o}}\times 0.07\,\,\lambda _{\text {o}}$ </tex-math></inline-formula> at 6.8 GHz) was obtained, which generated a highly stable broadside gain above 10 dBic throughout the entire operating AR bandwidth. This antenna had a measured −10 dB impedance bandwidth of 5.62–11.04 GHz (65.06%) and a 3 dB AR bandwidth of 5.64–7.89 GHz (33.25%). In addition, it had a measured 3 dB gain bandwidth of 5.17–8.2 GHz (45.32%), with a measured peak gain of 12.17 dBic.

Compact Patch Antenna Array With Fan-Beam Characteristics for Radar Application

In this paper, a compact 1×4 patch array antenna with a fan-beam radiation pattern is introduced for use in 3.5 GHz band applications. The proposed antenna consists of a planar two-layer printed structure so that the radiation elements and feeding network are located in the upper and lower layers respectively. In this way, the antenna has very compact dimensions while achieving a high radiation gain. Using a reflector plane under the antenna has improved the radiation pattern and decreased the antenna back radiation. The fabricated array antenna has an impedance bandwidth of 3.35-3.75 GHz (11.27%), a maximum realized gain of 10.91 dBi, and half power beamwidths (HPBWs) of 23.86° and 85.44° on the H- and E-panels, respectively. The overall dimensions of the antenna are 209×32.3×3.708 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> with a 250×50 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> conductive reflector at a distance of λ/4 from the antenna, and the theoretical and practical results show a good agreement with each other. The presented antenna is suitable for 5G systems and radar applications in the 3.5 GHz frequency band.