Single-negative Research Articles

Structural, morphological, optical and electrical properties of ferrite-based nanoparticles synthesized flexible substrate for chemical sensing application

A compact CaxCo(0.90-x)Zn0.10Fe2O4 based nanoparticles synthesized flexible microwave substrate with single negative (SNG) metamaterial is being successfully fabricated for industrial chemical contamination sensing applications. The unit cell dimensions of the MTM are 0.114λ × 0.114 λ × 0.017 λ. The nanoparticles, derived from the CaxCo(0.90-x)Zn0.10Fe2O4 material with varying Ca concentrations (Ca25, Ca50, and Ca75), have been synthesized using a sol-gel method, and their structural, morphological, and dielectric properties have been comprehensively characterized. Dielectric constants and loss tangents have been measured over the frequency range of 2–20 GHz. Simulation of the S21 response at 3.43 GHz, 6.50 GHz, 11.49 GHz, and 16.46 GHz has yielded maximum magnitudes of −52.78 dB, −48.07 dB, −52.16 dB, and −39.37 dB, respectively. Experimental verification on an FR-4 rigid substrate at 3.28 GHz, 6.58 GHz, 11.76 GHz, and 16.33 GHz has revealed magnitudes of −25.67 dB, −24.56 dB, −31.13 dB, and −25.17 dB. Finally, when fabricated on the flexible microwave substrate, the MTM displayed S21 responses of −48.31 dB, −43.12 dB, −61.80 dB, and −24.70 dB at 3.19 GHz, 6.62 GHz, 11.58 GHz, and 16.65 GHz, respectively. The MTM has exhibited SNG properties in distinct frequency bands and near-zero index (NZI) characteristics. The sensitivity, figure of merit (FOM), and Q-factor have been achieved at 0.096 GHz/RIU, 0.152 GHz/RIU, 0.846 (RIU−1), 0.846 (RIU−1), and 8.430, 29.801, respectively. Its performance has been validated through simulation, VNA measurements, and advanced design system (ADS) software analysis, showcasing promise for diverse applications in S-, C-, X-, and Ku-bands. The anticipated structure performs well in terms of its small size, flexibility, sensitivity, and lightweight, making it suitable for wireless communications and methanol and ethanol contamination sensing in industrial applications.

Propagation behavior in rectangular metallic waveguide periodically loaded with single negative metamaterial slabs

This paper focused on propagation characteristics of a single mode supporting waveguide enclosed by metallic sidewalls periodically loaded with lossless single negative (SNG) metamaterial slabs along axial direction. The gap between two successive SNG slabs is filled with a double positive (DPS) material. For the analysis, the periodic structure is assumed having symmetric unit cell (UC) and simplified as a two-port network which is one-half of the symmetric UC. Scattering parameters (S-parameters) are defined by even/odd mode analysis of the symmetric UC, and then the total S-parameters are calculated by solving the cascade connection of N unit cells. Eigenvalue equations are also obtained to explicit the solutions of band edge and pass/stopband diagrams in the microwave regime. Since a SNG can be either epsilon-negative (ENG) or mu-negative (MNG), S-parameters and dispersion behavior are illustrated with numerical examples and discussed for each periodic structure constructed with ENG or MNG slabs.

Wideband Compartment Shielding Technique for Miniaturized Packages Based on Electrically Small Single-Negative Meta-Diaphragm

This article focuses on realizing wideband compartment shielding in the shielding can packages of miniaturized high-speed chip modules and circuits. Because the conventional diaphragms with a low profile are difficult to cope with the high-order mode interference and evanescent wave interference, a new &#x201C;meta-diaphragm,&#x201D; which is based on the single-negative (SNG) metamaterial, is proposed to address these inherent problems. It is demonstrated that benefitting from the large propagation attenuation introduced by the proposed meta-diaphragm, a good shielding performance can be achieved at the first higher order resonance mode. Moreover, by elaborately embedding resistors in the meta-diaphragm, the additional interferences at other resonance frequencies can be significantly suppressed. Furthermore, the structure of the meta-diaphragm is optimized with two approaches: evolving from the single-band SNG structure to the double-band one and integrating with the parasitic patches. The two approaches enable its independent controlling ability at different frequency ranges and enhancement of low-frequency shielding performance. Based on the proposed technique, an experiment is implemented to suppress the resonance-dominated interference between the passive traces in a shielding can. The result agrees well with those from theoretical prediction. The final experimental shielding can&#x2019;s profile and width are 5 and 20 mm, respectively; the meta-diaphragm&#x2019;s profile is only 1.5 mm, i.e., &#x003C; 1/3 of shielding can&#x2019;s profile, and its electrically length is only 3 mm, i.e., <inline-formula> <tex-math notation="LaTeX">$0.1\lambda _{0}$ </tex-math></inline-formula> at 10 GHz, and the measured (simulated) meta-diaphragm can significantly suppress radio frequency interference (RFI) within 10.2&#x2013;17 GHz (10&#x2013;16.9 GHz) and realize <inline-formula> <tex-math notation="LaTeX">$&lt; -33.5$ </tex-math></inline-formula> dB (<inline-formula> <tex-math notation="LaTeX">$&lt; -40$ </tex-math></inline-formula> dB) coupling within 100 kHz&#x2013;18 GHz (dc-to-20 GHz). The miniaturized dimension and wideband results indicate that our proposed technique could meet the compartment shielding requirement of a series of miniaturized packages in the practical radio frequency (RF) chip modules and circuits.

Polarization insensitivity characterization of dual-band perfect metamaterial absorber for K band sensing applications

Polarization insensitive metamaterial absorbers (MA) are currently very attractive due to their unique absorption properties at different polarization angles. As a result, this type of absorber is widely used in sensing, imaging, energy harvesting, etc. This paper presents the design and characterization of a dual-band polarization-insensitive metamaterial absorber (MA) for K-band applications. The metamaterial absorber consists of two modified split ring resonators with an inner cross conductor to achieve a 90% absorption bandwidth of 400 MHz (21.4–21.8 GHz) and 760 MHz (23.84–24.24 GHz) at transverse electromagnetic (TEM), transverse electric (TE), and transverse magnetic (TM) mode. Polarization insensitivity of different incident angles for TE and TM mode is also investigated, which reveals a similar absorption behavior up to 90°. The metamaterial structure generates single negative (SNG) property at a lower frequency of 21.6 GHz and double negative property (DNG) at an upper frequency of 24.04 GHz. The permittivity and pressure sensor application are investigated for the proposed absorber, which shows its useability in these applications. Finally, a comparison with recent works is also performed to demonstrate the feasibility of the proposed structure for K band application, like sensor, filter, invasive clock, etc.

Dual-band THz antenna with SNG loads for biosensing and early skin cancer detection with Fano response: A numerical study

THz spectrum is one of the safest areas of light for the body which can be considered in biomedical sensing applications in the human body and can be utilized for high sensitivity detection. In this paper, a THz antenna with a single negative (SNG) load is developed for early cancer detection application. The SNG load is useful to increase the gain and efficiency of the antenna. The primary antenna has a circular slot on the ground plane. Metamaterial element is placed on the cylindrical dielectric. The total size of the antenna is 400 × 400 μm 2 and the loss-less quartz substrate is used to design the proposed antenna. In addition, the SNG load provides dual-band characteristics, and the proposed antenna covers 0.85 and 1 THz with high directivity and efficiency which is more than 90%. The achieved results proved that the antenna has higher sensitivity at a lower frequency. Moreover, we showed the proposed dual-band antenna can be used to increase the sensing accuracy of the device to detect the progress of cancer in a specific sample.

An octagonal split ring resonator-based double negative metamaterial for S-, X- and Ku-band applications

This study aimed to produce a miniaturised double negative metamaterial with a lower resonance frequency. Therefore, a new combination of a multi-circular ring connected with octagonal shape ring metamaterial was developed on a 9 × 9 mm2 dielectric substrate material with a thickness of 1.6 mm, named the Flame Retardant 4 (FR-4). While the selected frequency ranged between 0 and 18 GHz for the unit and array metamaterial design. Numerical simulation was used for the design and analysis of the proposed metamaterial. A few analysis were performed to validate the performance of the new design including the analyses of the different dimensions of the substrate and varying widths of the split gaps. The proposed design structure manifested resonance frequencies at S, X and Ku-bands. The resonance frequency at S-band (3.31 GHz) and X-band (8.60 GHz) presented double-negative (DNG) metamaterial behaviour while X-band (11.93 GHz) and Ku-band (12.99 GHz) presented single-negative (SNG) medium characteristics. The simulation and measured results almost coincided with each other. The compactness of the proposed design was proven by the effective medium ratio (EMR) of 10.07. In conclusion, the miniaturised structure can be accredited for satellite communication and radar applications.

Penta band single negative meta-atom absorber designed on square enclosed star-shaped modified split ring resonator for S-, C-, X- and Ku- bands microwave applications

This paper represents a penta band square enclosed star-shaped modified split ring resonator (SRR) based single negative meta-atom absorber (MAA) for multi-band microwave regime applications. FR-4 low-cost material has been used as a substrate to make the MAA unit cell with 0.101λ0 × 0.101λ0 of electrical size, where λ0 is the wavelength calculated at the lower resonance frequency of 3.80 GHz. There are two outer square split ring and one inner star ring shape resonator of 0.035 mm thickness of copper placed on the one side, and another side of the substrate has full copper to construct the desired unit cell. The MAA unit cell provides five absorption peaks of 97.87%, 93.65%, 92.66%, 99.95%, and 99.86% at the frequencies of 3.80, 5.65, 8.45, 10.82, and 15.92 GHz, respectively, which covers S-, C-, X-, and Ku- bands. The properties of MAA have been investigated and analyzed in the E-, H-fields and surface current. The EMR and highest Q factor of the designed MAA is 9.87 and 30.41, respectively, and it shows a single negative (SNG) property. Different types of parametric analysis have been done to show the better performance of absorption. Advanced Designed System (ADS) software has been used for equivalent circuit to verify the simulated S11 result obtained from the CST-2019 software. Experimental outcomes of the MAA unit cell have a good deal with the simulated result and measured result of the 24 × 20 array of unit cells also shown. Since the unit cell provides superior EMR, excellent Q-factor, and highest absorption so the recommended MAA can be effectively used as a penta band absorber in microwave applications, like notch filtering, sensing, reducing the unintended noise generated with the copper component of the satellite and radar antennas.

Synthesis and characterization of Mg\u2013Zn ferrite based flexible microwave composites and its application as SNG metamaterial

In this article, we propose SNG (single negative) metamaterial fabricated on Mg–Zn ferrite-based flexible microwave composites. Firstly, the flexible composites are synthesized by the sol-gel method having four different molecular compositions of MgxZn(1−x)Fe2O4, which are denoted as Mg20, Mg40, Mg60, and Mg80. The structural, morphological, and microwave properties of the synthesized flexible composites are analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and conventional dielectric assessment kit (DAK) to justify their possible application as dielectric substrate at microwave frequency regime. Thus the average grain size is found from 20 to 24 nm, and the dielectric constants are 6.01, 5.10, 4.19, and 3.28, as well as loss tangents, are 0.002, 0.004, 0.006, and 0.008 for the prepared Mg–Zn ferrites, i.e., Mg20, Mg40, Mg60, and Mg80 respectively. Besides, the prepared low-cost Mg–Zn ferrite composites exhibit high flexibility and lightweight, which makes them a potential candidate as a metamaterial substrate. Furthermore, a single negative (SNG) metamaterial unit cell is fabricated on the prepared, flexible microwave composites, and their essential electromagnetic behaviors are observed. Very good effective medium ratios (EMR) vales are obtained from 14.65 to 18.47, which ensure the compactness of the fabricated prototypes with a physical dimension of 8 × 6.5 mm2. Also, the proposed materials have shown better performances comparing with conventional FR4 and RO4533 materials, and they have covered S-, C-, X-, Ku-, and K-band of microwave frequency region. Thus, the prepared, flexible SNG metamaterials on MgxZn(1−x)Fe2O4 composites are suitable for microwave and flexible technologies.

Design of a Dual Band SNG Metamaterial Based Antenna for LTE 46/WLAN and Ka-Band Applications

The non-existing properties of the metamaterial surfaces can be utilized to improve the antenna radiation characteristics. In this article, a design and performance analysis of a Single Negative (SNG) metamaterial based antenna is imparted for LTE 46/WLAN and Ka-band (like in satellite communication for the receiving side) applications. The unit cell of the metamaterial surface exhibits negative permittivity and positive permeability; yielding a high magnitude positive refractive index, is used to improve and analyze the performance of the proposed monopole antenna element. The proposed SNG based antenna covers a -10 dB bandwidth from 5.35-5.69 GHz (LTE 46/WLAN) and 17.81-20.67 GHz (Ka-band). The total size of the proposed antenna element is 20.2×28.4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while a 2×3 SNG metamaterial surface is used at the back of the antenna element which improves the gain from 4.52 dB to 9.13 dB for the desired Ka band and 1.17 to 5.04 dB for the LTE 46/WLAN band. Furthermore, for the LTE 46/WLAN frequency band, the impedance matching also gets better, resulting in the return loss improvement from -11 dB to -32.4 dB. Moreover, the radiation efficiency is also improved by more than 10 % for the Ka band after employing the SNG metamaterial surface. The measured results fall in good agreement with the simulated one and make the proposed SNG metamaterial based antenna design competent for the LTE 46/WLAN and Ka-band (like in satellite communication for the receiving side) applications.

SNG and DNG meta-absorber with fractional absorption band for sensing application

This paper reports on a tunable transmission frequency characteristics-based metamaterial absorber of an X band sensing application with a fractional bandwidth. Tunable resonator metamaterial absorbers fabricated with dielectric surface have been the subject of growing attention of late. Absorbers possess electromagnetic properties and range modification capacity, and they have yet to be studied in detail. The proposed microstructure resonator inspired absorber with triple fractional band absorption consists of two balanced symmetrical vertical patches at the outer periphery and a tiny drop hole at two edges. Experimental verification depicted two absorption bands with single negative (SNG) characteristics for two resonances, but double negative (DNG) for single resonance frequency. The mechanism of sensing and absorption was analyzed using the transmission line principle with useful parameter analysis. Cotton, a hygroscopic fiber with moisture content, was chosen to characterize the proposed absorber for the X band application. The electrical properties of the cotton changed depending on the moisture absorption level. The simulation and the measured absorption approximately justified the result; the simulated absorption was above 90% (at 10.62, 11.64, and 12.8 GHz), although the steady level was 80%. The moisture content of the cotton (at different levels from 0 to 32.13%) was simulated, and the transmission resonance frequency changed its point in two significant ranges. However, comparing the two adopted measurement method and algorithm applied to the S parameter showed a closer variation between the two resonances (11.64 and 12.8 GHz) which signified that a much more accurate measurement of the cotton dielectric constant was possible up to a moisture content of 16.1%. However, certain unwanted changes were noted at 8.4–8.9 GHz and 10.6–12.4 GHz. The proposed triple-band absorber has potential applications in the X band sensing of moisture in capsules or tablet bottles.

Compact Ultra-Wideband Monopole Antenna Loaded with Metamaterial.

A printed compact monopole antenna based on a single negative (SNG) metamaterial is proposed for ultra-wideband (UWB) applications. A low-profile, key-shaped structure forms the radiating monopole and is loaded with metamaterial unit cells with negative permittivity and more than 1.5 GHz bandwidth of near-zero refractive index (NZRI) property. The antenna offers a wide bandwidth from 3.08 to 14.1 GHz and an average gain of 4.54 dBi, with a peak gain of 6.12 dBi; this is in contrast to the poor performance when metamaterial is not used. Moreover, the maximum obtained radiation efficiency is 97%. A reasonable agreement between simulation and experiments is realized, demonstrating that the proposed antenna can operate over a wide bandwidth with symmetric split-ring resonator (SSRR) metamaterial structures and compact size of 14.5 × 22 mm2 (0.148 λ0 × 0.226 λ0) with respect to the lowest operating frequency.

Numerical Analysis of Single Negative Broadband Metamaterial Absorber Based on Tri Thin Layer Material in Visible Spectrum for Solar Cell Energy Harvesting

A broadband nanostructure metamaterial absorber (MA) based on tri-layer metallic-optical-thin film molded shape is proposed for visible spectrum solar energy scavenging. This MA is investigated for photon mobility to achieve significant photon conversion and absorption to integrate into solar cell technology, IoT components, or energy harvesting. Design and analysis of the proposed MA were performed using the “Yee’s Finite-Difference Time-Domain (FDTD)” method based on commercially available CST microwave studio simulation software. Numerical computational tools depict an absorptivity of higher than 80%, which covered nearly the visible region 430~627 THz. This significant absorptivity can be maintained with both transverse electric and transverse magnetic polarizations. Furthermore, molded shape with two-dimensional split and nano-square window expedites the unit cell to exhibit single negative (SNG) metamaterial characteristics and photon conversion acceleration. Compared with related previously reported broadband absorbers, the proposed MA has promising application, in conventional solar cell efficiency improvement and emitter.

Design of a Novel Double Negative Metamaterial Absorber Atom for Ku and K Band Applications

This paper presents a multiband metamaterial (MM) absorber based on a novel spiral resonator with continuous, dual, and opposite P-shape. The full wave analysis shows 80.06% to 99.95% absorption at frequencies range for Ku and K bands for several substrate materials of 100 mm2 area. The results indicate that the absorption rate remains similar for different polarizing angles in TEM mode with different substrates. With FR4 (Flame Retardant 4) substrate and 64 mm2 ground plane, the design acts as single negative (SNG) MM absorber in K band resonance frequencies (19.75–21.37 GHz) and acts as double negative (DNG) absorber in Ku band resonance frequencies (15.28–17.07 GHz). However, for Rogers 3035 substrate and 36 mm2 ground plane, it acts as an SNG absorber for Ku band resonance frequency 14.64 GHz with 83.25% absorption and as a DNG absorber for K band frequencies (18.24–16.15 GHz) with 83.69% to 94.43% absorption. With Rogers 4300 substrate and 36 mm2 ground plane, it acts as an SNG absorber for Ku band at 15.04 GHz with 89.77% absorption and as DNG absorber for K band frequencies (22.17–26.88 GHz) with 92.87% to 93.72% absorption. The design was fabricated with all three substrates and showed quite similar results as simulation. In comparison with other broadband absorbers, this proposed MM absorber illustrated broad incidence angles in TEM mode.

Tunable optical meta-surface using graphene-coated spherical nanoparticles

Graphene-coated spherical nanoparticles are proposed as the unit cells of a single negative (SNG) meta-surface at infrared frequencies. To derive the effective permittivity of the meta-surface, each graphene layer is represented as a thin shell with complex conductivity calculated by the Kubo formulas. Later, based on the modified Mie Lorenz coefficients of the particle, electric polarizability of the unit cell is obtained, to be used in the Clausius–Mossotti effective medium formulation. The proposed structure has lower optical losses in comparison to its noble metal counterparts and it is tunable by varying the bias voltages of graphene shells. Moreover, material and geometrical parameters of the particles along with the filling fraction of the meta-surface are other parameters for the control of the optical response in the target frequency. A deep sub-wavelength tunable perfect reflector is considered as an instance. Two possible applications of the designed reflector are in lenses and semiconductor laser cavities, as a promising replacement to Bragg reflectors.

Coupling Reduction for a Wideband Circularly Polarized Conformal Array Antenna With a Single-Negative Structure

Decoupling of a wideband circularly polarized (CP) conformal array is studied by a single-negative (SNG) metamaterial (MTM) isolator. The conformal array consists of two wideband CP antennas, which are assembled on an arched carrier, and a wideband SNG structure is placed between the antenna elements for coupling reduction. The SNG structure consists of four wheel-shaped units concentrically. The SNG structure is bianisotropic, and its constitutive parameters are tailored to form a wide isolation band. By using the proposed wideband SNG structure, the mutual coupling between the conformal antenna elements is reduced up to 25 dB at 4.5 GHz, and the mutual coupling is improved in the 3.9–5.05 GHz band. In addition, the loading of the SNG structure has little effect on the axial-ratio bandwidth. Besides, the gain and radiation patterns are improved. This research provides some basis in the decoupling of the conformal array.

Electromagnetic coupling reduction in dual-band microstrip antenna array using ultra-compact single-negative electric metamaterials for MIMO application**Project supported by the National Natural Science Foundation of China (Grant No. 61372034).

In this paper, an ultra-compact single negative (SNG) electric waveguided metamaterial (WG-MTM) is first investigated and used to reduce the mutual coupling in E & H planes of a dual-band microstrip antenna array. The proposed SNG electric WG-MTM unit cell is designed by etching two different symmetrical spiral lines on the ground, and has two stopbands operating at 1.86 GHz and 2.40 GHz. The circuit size is very compact, which is only (where λ0 is the wavelength at 1.86 GHz in free space). Taking advantage of the dual-stopband property of the proposed SNG electric WG-MTM, a dual-band microstrip antenna array operating at 1.86 GHz and 2.40 GHz with very low mutual coupling is designed by embedding a cross shaped array of the proposed SNG electric WG-MTM. The measured and simulated results of the designed dual-band antenna array are in good agreement with each other, indicating that the mutual coupling of the fabricated dual-band antenna array realizes 9.8/11.1 dB reductions in the H plane, 8.5/7.9 dB reductions in the E plane at 1.86 GHz and 2.40 GHz, respectively. Besides, the distance of the antenna elements in the array is only 0.35λ0 (where λ0 is the wavelength at 1.86 GHz in free space). The proposed strategy is used for the first time to reduce the mutual coupling in E & H planes of the dual-band microstrip antenna array by using ultra-compact SNG electric WG-MTM.

Transmission Properties in Lossy Single-Negative Materials

We theoretically investigate the transmission properties at an interface between a dielectric and a lossy single-negative (SNG) material. The transmission property is specifically investigated in the refractive angle calculated by the inhomogeneous wave theory. With the existence of a loss in an SNG material, the calculated refractive angle can be negative. That is, the negative refraction phenomenon, which is an important consequence in a double-negative (DNG) material, can also be found in an SNG material. We analyze the refractive angle as functions of the angle of incidence, the wave frequency, and the loss. For the epsilon-permittivity SNG material, the frequency-dependent negative refractive angle is shown to possess a critical frequency at which the absolute value in the negative refractive angle attains a maximum.

Dual-band Band-pass Filters Based on Metallic Via Holes

Abstract This paper presents compact dual-band band-pass filters (BPFs) using microstrip transmission lines (TLs) loaded with metallic via holes (MVHs). The primary goals of the proposed design are to get size reduction and dual-band frequency response. An end-coupled line dual-band BPF with better size reduction has been obtained using MVHs as a single negative (SNG) metamaterial (MTM) component to achieve negative relative permittivity (ɛ r ). This component is adequate for designing dual-band BPFs to operate at 4.1 GHz and 6 GHz resonant frequencies. To the best knowledge of the authors of this work, “Dual-” band BPF based on MVH has not been experienced yet by any other work in the literature. The filters structure length is as small as one third of wavelength. The filters have been designed with a fractional bandwidth (δ) that exceeds 10% at the resonant frequencies. Numerical observations of the microstrip TL and end-coupled BPFs designs have all been discussed. Simulations were done by HFSS software and implemented on the substrate Roger RO3210 with dielectric constant of 10.8 and dielectric substrate height of 1.27 mm. These filters are convenient for most common microwave applications.

Reflection and transmission properties of a wire grid embedded in a SNG or SZ medium

The reflection and transmission properties of a wire grid embedded in lossless Single Negative (SNG) or Single Zero (SZ) medium have been analytically studied. The wires of the grid are taken to be lossless as well as lossy. It is shown that a lossy grid has approximately identical reflection characteristics for the Transverse Magnetic incident wave with Epsilon Negative and Mu Negative background medium. The lossy grid with Epsilon Zero background medium acts as a perfect reflector for the normally incident wave. Likewise, it is further studied that a lossy wire grid embedded in Mu Zero medium can be cloaked for the incoming normally incident wave.

EFFICIENT ISOLATION BETWEEN ELECTRICALLY SMALL METAMATERIAL-INSPIRED MONOPOLE ANTENNAS

In this paper, a new electrically small metamaterial-inspired monopole antenna is presented. It consists of a simple square-shaped coplanar waveguide (CPW-fed) monopole with an embedded complementary split ring resonator (CSRR). It operates at three distinct frequency ranges around 2.45, 4.2, and 5.8 GHz, with low return loss and uniform radiation patterns, making it a perfect candidate for modern wireless applications. Furthermore, using this as a primary unit to construct two different 2 × 2 MIMO configurations, we achieve systematic minimization of mutual coupling, using additional single negative (SNG) metamaterial-inspired resonators. Mutual coupling is reduced by as much as 27 dB at the frequency of interest. Simulated and measured results of all antennas are in good agreement.