EM Simulation Results Research Articles

A Bandpass Filter Realized by Using Pixel Structure and Genetic Algorithm Optimization.

This paper presents a flexible method for designing a bandpass filter (BPF) using pixel structure and genetic algorithm (GA) optimization. The pixel structure is made up of a grid of metallic microstrip stubs, and the GA is utilized to determine the connections between these stubs. The pixel structure enables the construction of step impedance and shunt branches, which are used to design a traditional BPF. To enhance the design freedom, one side of the discrete grids is connected to the ground via metallic holes. For verification, a BPF was designed, simulated, and measured. The experimental results showed that the 10 dB return loss bandwidth ranges from 1.1 to 1.9 GHz and the insertion loss is approximately 2.5 dB. There is good agreement between the calculation, EM simulation, and measurement results. The proposed GA-based design method offers significant advantages in terms of one-time EM simulation, feasibility, and labor time savings, making it more convenient than the traditional design method.

A Dual-Band Dual-Output Filtering Power Amplifier Based on High-Selectivity Filtering Impedance Transformer

In this brief, a novel filtering impedance transformer with good selectivity and high termination impedance is proposed, of which close-formed design equations are derived and effectively verified. Then, a dual-band dual-output filtering power amplifier (PA) operating at 2.4-2.6 GHz and 3.4-3.6 GHz is designed based on the proposed filtering impedance transformer. The dual-band filtering PA contains a diplexer-like output matching network, which can separate two band signals into corresponding output branches. EM-simulated results of the diplexer-like output matching network show that the isolation between the two output ports is better than 30.7 dB. Finally, for demonstration, the dual-band dual-output filtering PA using a packaged 10 W transistor is fabricated, and the measured drain efficiencies are 45.3%-50.2% and 41.7%-53.2% at lower and higher bands, respectively. Also, a good dual-band filtering response is obtained. A good agreement between simulated and measured results is observed.

On Body and Off‐Body Performance Analysis of an Ashoka Tree Shaped Wearable Textile Antenna for Biomedical and Military Applications

AbstractIn this paper an Ashoka tree shaped wearable textile antenna for biomedical and military applications working at 2.4 GHz, 9.04 GHz is investigated and analyzed. The designed antenna has the size of 34 × 40 × 1 mm3. To obtain a wide bandwidth 0.5 × 40 mm2 partial ground plane is used. The lightweight jean material is employed as a non‐conductive dielectric substance with a εr of 1.7 and a substrate height of 1 mm to define the wearable applications. Examining the surface current and actualizing the conductivity of the radiating elements are performed. Full‐wave EM simulation and experimental results are carried out at 30°,60°, and 90° under various bending conditions, both in free space and close to the human body. The suggested antenna performs satisfactorily in terms of gain and specific absorption rate. When worn on the body, the final design offers a peak gain of 7.6 dBi and an efficiency of 94.7%. Findings from simulations using CST Microwave Studio and measurements are quite close. These characteristics show that the suggested antenna is a solid contender for wearable applications that are both off‐ and on‐body. Due to its compatibility, adaptability in structure design and shape, excellent performance at various angles, human safety, miniaturization, power consumption, etc., this Ashoka tree‐shaped antenna can be significantly used in military jackets and in biomedical applications.

Low cross polarized leaf shaped broadband antenna with metasurface as superstrate for sub 6 GHz 5 G Applications

This article presents the design, circuit model analysis, and realization of a metasurface-based novel leaf-shaped antenna for sub 6 GHz 5 G NR frequency bands like n77 (3.3–4.2 GHz), n78 (3.3–3.8 GHz), n79 (4.4–5 GHz), and n90 (2.4–2.6 GHz) applications. Primarily, a leaf-shaped microstrip planar antenna is designed and provides a broad impedance bandwidth of 77.43% (2.2–4.98 GHz), a peak gain of 4.51 dBi, and a high radiation efficiency of 94.16%. The planar antenna is integrated with a 5 × 3 elements periodic metasurface (MS) array to enhance radiation performance. Both the radiating leaf planar and the MS layer have been designed on a low-cost FR4 epoxy substrate, and equivalent circuit models have been developed for both successively to validate the EM simulated results. The overall dimensions of the planar antenna with MS layer are 0.45 λ0 × 0.27 λ0 × 0.108 λ0, (λ0 corresponds to lowest resonant frequency f=2.7 GHz). The tested antenna with MS superstrate covers a broad range of operating frequencies from 2.29 to 4.78 GHz (2.49 GHz) with a − 10 dB impedance fractional bandwidth of 70.43% and has an excellent reflection coefficient of more than − 35 dB for the entire operating band. The experimental peak gain and higher radiation efficiency are 8.76 dBi and 96.6%, respectively. Moreover, all these parameters are extremely high in single-layer planar antennas, including the stable omnidirectional radiation pattern with very low cross-polarization of − 53.34 dB.

Novel coil design and analysis for high-power wireless power transfer with enhanced Q-factor

The power transfer efficiency (PTE) is a crucial aspect for effective wireless power transfer (WPT) applications. The quality factor (Q) of the WPT coil plays a critical role in ensuring higher PTE. In this paper, a novel method of improving the Q of a WPT coil is proposed. Resistance reduction techniques are presented which involves variation of the trace pitch, width, and thickness. This approach targets the high AC losses centered in the inner turns, which subsequently results in an increased Q. Numerical analysis with respect to the inductance and resistance models are presented, analyzed, and compared to that of the EM simulation results. To verify the efficacy of the proposed coil structure, a prototype is fabricated where good agreement is achieved between the measured and simulated results. The proposed coil attained a quality factor increment of about 19.24% at 85 kHz in comparison to the conventional one. The proposed technique can be used to optimize planar spiral coils to attain higher Q.

Design of a novel compact highly selective wideband bandstop RF filter using dual path lossy resonator for next generation applications.

This article presents the design of a wideband bandstop RF filter intending to improve selectivity and compactness. Conventional bandstop filter topology with finite unloaded quality factor produces degraded bandstop filter performance due to dissipation loss. In the proposed filter design, a novel dual path Capacitive Coupled Step Impedance Resonator (CCSIR) structure is used to obtain an infinite stopband attenuation. A uniform impedance resonator is used in Path 1, whereas Path 2 contains a resonator that is twice coupled to the transmission lines. The electrical length of both paths is chosen to be out of phase, resulting in a high rejection level at higher frequencies. It has been analyzed that the selectivity can be improved by increasing the order of the dual coupled step impedance resonator. The proposed design produces a wideband BSF centered at 5.25 GHz with a high rejection level of 104.3 dB and fractional bandwidth of 58.5%. The results have demonstrated that the resonant frequencies are regulated by varying the electrical length of CCSIR. Moreover, it has been realized that out of phase signal cancellation due to the dual path is involved in producing the finite frequency transmission poles, which further enhances the filter selectivity. However, the same electrical performance can only be achieved from coaxial cavities and waveguides due to the high-quality factor. The proposed topology is fabricated and measured on a high-frequency microstrip substrate having a low-quality factor with a compact output and better electrical performance compared to coaxial cavities or waveguides. Due to its high electrical performance and small size, the proposed BSF is appropriate for 4G and 5G (FR1) applications. The measurement shows good concurrence with the full-wave EM simulated results. The fabricated prototype of third order BSF has a compact size of (0.7 × 0.77)λg at 5.25 GHz.

Broadband dual‐band bandstop filters based on step‐impedance stubs and transmission‐line networks

In this paper, a novel basic structure of a dual-band bandstop filter (DBSF) without coupled lines is proposed. In order to improve the performance, some optimizations are made to the basic structure, and two DBSF structures with multi-transmission zeros and multi-transmission poles are obtained. These filters have the advantages of simple structure, high selectivity, and high stopband rejection, among which the deepest stopband can be better than 45 dB. In addition, an extraction method of transmission zeros and transmission poles based on the S-parameter theory is proposed. The ideal 3-dB fractional bandwidths of the basic structure are 37.8% and 18.7%, respectively, 54.1% and 25.9% for the first improved structure, respectively, and 75.1% and 34.2% for the second improved structure, respectively. EM simulation results and measured results are highly unified to verify the proposed filter structure.

A physical‐based model for on‐chip double‐layer spiral inductors with a ground shield

AbstractA physical‐based analytical model for double‐layer inductors to reduce the on‐chip area occupied is presented. A simple DC inductance model is developed based on self‐inductance and mutual inductance of metal segments. A new method has been adopted to accurately estimate the nonuniform distribution of currents due to skin and proximity effects, and a ladder structure is used to characterize them. Dielectric and substrate electric effects are analyzed, and a ground shield is used to reduce losses. The effective inductance reduction due to the eddy current in the silicon substrate is modeled by a negative mutual inductance between the metal spiral lines and the substrate. All the model parameters can be calculated from the structure sizes and process parameters. On‐chip inductors with different parameters were fabricated for the verifications. The EM simulated results and measured results are in good agreement with the proposed model. Thus, it is suitable for different technologies. This model can facilitate the design and optimization of on‐chip inductors for RF IC applications.

Compact low-pass filter (LPF) with wide harmonic suppression using interdigital capacitor

Abstract In this article, a compact microstrip low-pass filter (LPF) with low in-band insertion loss and a wide attenuation band is recommended. The structure is modeled using two rectangular-shaped open resonators (ORs) loaded with multiple sections of the interdigital capacitor. The proposed LPF has a cut-off frequency of 1.5 GHz, a passband insertion loss of 0.35 dB, and an electrical circuit size of 0.02 λ g 2. In the ground plane, two dissimilar defected ground structures (DGSs) are introduced to generate additional attenuation poles for enriching the stopband performance of the LPF. The harmonics suppression is achieved up to 15 GHz with tenth harmonic suppression and relative stopband rejection of almost 165%. The EM simulated results show a well-matched behavior with the experimental ones. The proposed LPF can be used for global positioning systems (1500 MHz), telecommunications (1600 MHz), and audio broadcasting (1400 MHz) applications.

Analysis and design of a single layer double square slot frequency selective surface with single stopband between double passbands

AbstractSquare loop and square slot are the simplest and commonly used elements of frequency selective surfaces (FSSs) providing bandstop and bandpass responses, respectively. Despite it is already known that employment of a double square slot structure presents a tunable stopband between two passbands, it is not clear which parameters of the structure are crucial for tuning the inbetween stopband. We propose an analysis of a double square slot FSS considering its element as a parallel connection of square slot and square loop predicting two geometrical parameters of the constituent square loop are crucial for tuning the inbetween stopband. The stopband is tunable by changing geometrical parameters of the constituent square loop and does not depend on geometries of the constituent square slot. The validity of this analytical prediction is verified by full wave EM simulation results.

A sub-30 GHz differential-frequency tripler in 22-nm FDSOI technology for FMCW spectrum

In this work, a wide-band Frequency-Tripler is designed to cover Frequency-Modulated Continuous Wave radar (FMCW) in 22-nm CMOS-FDSOI Technology. The designed frequency Tripler upconverts sub-30 GHz signal to cover a wide-band FMCW spectrum (72–84 GHz). In this paper, the silicon validated results of a VCO combined with the proposed frequency Tripler are presented. The design architecture, EM simulation results, measurement setup and silicon result of our fabricated die are covered in this paper. The designed circuit consumes 20 mA of current at the supply voltage of 800 mV. The Tripler works in the input frequency range from 24 GHz to 32 GHz, delivering a wide-band frequency output of 72–96 GHz. The differential output of VCO is capacitively coupled with the input of the multiplier.

Transmissive type dual band polarization converter integrated microstrip patch antenna in THz regime

This article proposes the generation of both LHCP and RHCP waves simultaneously –at two distinct frequencies by using a single-layered compact polarization converter (PC). The proposed PC has been designed with a gold pattern inscribed on a polyimide substrate. A modified I-shaped structure with semi-circular curved ends provides a quadrature phase shift between the orthogonal components of the incident electric field with a high transmission coefficient and low insertion loss across the two THz frequency bands. Two equivalent circuit models have been proposed for TE and TM modes separately. As a proof of concept of the proper functioning of the proposed PC, one dual-band linearly polarized antenna is designed and integrated with the PC. The linearly polarized radiated waves from the dual-band antenna across 1.55 THz and 4.05 THz have been successfully converted into both the RHCP and LHCP waves simultaneously. The integration of a simple profile PC with a dual-band THz antenna to produce dual CP radiated waves simultaneously are the key achievements of this proposed work. Moreover, the results of equivalent circuit models for both TE and TM modes are justified after proper validation with the full-wave EM simulation results. The proposed dual-band PC, dual-band THz antenna, and the integrated structures are systematically investigated using FEM-based CST Microwave studio.

Stepped Impedance Hairpin Resonator (SIHR) based Compact Lowpass Filter with Wide Attenuation Band

ABSTRACT In this article, a compact (0.29 λg x 0.10 λg) low-pass filter (LPF) using a trisection stepped impedance hairpin resonator (SIHR) with a low insertion loss and a wide attenuation band is proposed. The microstrip structure is loaded with an L-shaped spur-line resonator and folded T-shaped stub for generating additional transmission zeroes to obtain a wider attenuation band. Moreover, an open stub is introduced into the existing structure to enrich the stopband performance of the LPF with a relative stopband rejection of almost 142 %. The proposed LPF that operates at a cut-off frequency of 1.7 GHz is suppressed up to −46 dB at the resonant frequency with a passband insertion loss of 0.35 dB. The suppression of harmonics is achieved up to 10 GHz with a suppression factor of 2. A well-matched behavior is observed in between the EM simulated, measurement, and circuit simulated results. The proposed LPF is suitable for mobile phones (1850 MHz), a global system for mobile communications (1800 MHz), and LTE communications (1700 MHz).

Non-Uniform Pitch Helical Resonators for Dual-Passband Filter Design

This paper presents a study of a non-uniform pitch helical resonator (NPHR) structure and the coupling mechanisms to design dual-passband filters. The previous research analyzes NPHR as a type of step impedance resonator (SIR), however, it does not give analytical equations or prediction for the dual-resonance characteristics of the NPHR structure discussed in this paper. Consequently, a circuit model is proposed to analyze the dual-resonance characteristics of NPHRs. Analytical equations are derived, showing that the frequency ratio of a dual-band NPHR can be determined by the ratio of turns. EM simulation and experimental results have shown good agreement with the circuit analysis. The derived analytical equations from circuit model can be used for fast design of NPHRs. A step-width aperture is proposed to independently control the coupling coefficients at the each band of NPHRs. A third order dual-passband filter has been designed and fabricated. The filter has 3.3% and 3% fractional bandwidths at 789 MHz and 2402 MHz, respectively. The designed prototype filter shows that NPHRs can be utilized to realize compact filters with dual-band characteristics. The filter design can be extended from engineering perspective for application in wireless communication systems.

A Wearable Circularly Polarized Antenna Backed by AMC Reflector for WBAN Communications

A new flexible circularly polarized (CP) wearable antenna is proposed for Wireless Body-Area Network systems (WBAN) operating at 5.8 GHz. The circular polarization is enabled by combining a microstrip-line monopole feed and an inverted L-shaped conformal metal strip extended from a coplanar waveguide. The proposed antenna shows satisfactory performance in terms of gain and specific absorption rate (SAR) at a separation of 12 mm from a human body model. To minimize body-antenna separation, a flexible <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> artificial magnetic conductor (AMC) was used as a reflector to achieve good performances in terms of gain and SAR. The total footprint of the proposed antenna is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$34.4\times34.4$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.384 \lambda _{0}^{2}$ </tex-math></inline-formula> ) board of semi-flexible Rogers RT-Duroid 5880 substrate. The final design provides a peak gain of 7.6 dBi and an efficiency of 94.7% when worn on the body. Furthermore, evaluation results indicate that the maximum SAR level decreased by up to 20.42% in comparison with the CP antenna without the AMC. Full-wave EM simulation and experimental results are performed, both in free space and proximity to the human body under different bending scenarios. Overall, the proposed antenna performance has been shown to be robust to structural deformation along the x-axis in comparison to previously reported designs. These features demonstrate that the proposed antenna is a strong candidate for off-body wearable applications.

Design of a High-Gain Single Circular Patch Radiator With a Cavity-Backed Structure Using Multiple SIW Feeders for Monopulse DF-Applications

This paper proposes the design of a gain enhanced single circular patch radiator (SCPR) with a cavity-backed structure using multiple substrate integrated waveguide (SIW) feeders for monopulse systems. We derive the equations of a radiation pattern for the multi-feed SCPR and compare it with the full EM simulation results. Based on the theoretical results, the proposed SCPR with multiple feeds is designed by adding the cavity-backed structure to obtain high gain characteristics. In the feeding network, four SIW structures are designed and circularly arranged, which can reduce loss and mutual coupling. Each pair of the SIW feeders can provide sum ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma$ </tex-math></inline-formula> ) and difference ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta$ </tex-math></inline-formula> ) patterns to achieve the monopulse direction finding (DF) properties in both elevation and azimuth directions. To verify the feasibility, the proposed antenna is fabricated, and the antenna characteristics are measured. The measured reflection coefficient is −14.5 dB at 5.8 GHz, and the maximum gains are 4.9 dBi and 4.8 dBi in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">zy</i> -plane. To observe the monopulse DF, the estimated direction of arrival (DOA) results are examined in both elevation and azimuth directions. In the whole estimated angle range, the estimation error is lower than 0.49, and the average error is 0.26.

Compact EBG structure for ground bounce noise suppression in high-speed digital systems

&lt;abstract&gt; &lt;p&gt;This paper proposes Inductive Enhanced-Electromagnetic Bandgap (IE-EBG) structure to suppress the Ground Bounce Noise (GBN) for high-speed digital system applications. The GBN excited between the power and ground plane pair could be a source of interference to the adjacent analog IC's on the same PCB (or) nearby devices because of radiated emission from the PCB edges. Hence, it must be suppressed at the PCB level. The proposed two-dimensional IE-EBG patterned power plane suppressed the GBN effectively over a broad frequency range. The four unit-cell IE-EBG provides a -40 dB noise suppression bandwidth of 13.567 GHz. With a substantial increment in the overall area, the nine unit-cell IE-EBG provides a -50 dB bandwidth of 19.02 GHz. The equivalent circuit modeling was developed for nine unit-cell IE-EBG and results are verified with the 3D EM simulation results. In addition, dispersion analysis was performed on the IE-EBG unit-cell to validate the lowest cut-off frequency and bandgap range. The prototype model of the proposed IE-EBG is fabricated and tested. The measured and simulated results are compared; a negligible variation is observed between them. In a multilayer PCB, the solid power plane is replaced with the 1 x 4 IE-EBG power plane and its impact on high-speed data transmission is analyzed with single-ended/differential signaling. The embedded IE-EBG with differential signaling provides optimum MEO and MEW values of 0.928 V, 0.293 ns for a random binary sequence with the 0.1 ns rise-time. Compared to single-ended signaling, embedded IE-EBG with differential signaling maintain good signal integrity and supports high-speed data transmission.&lt;/p&gt; &lt;/abstract&gt;

Designing and Validation of Miniaturized CPW Based Microwave Notch Filter Using Loaded Modified Multiple Split Ring Resonator (MSRR)

In this article, a coplanar waveguide (CPW) based compact low loss notch filter (NF) with sharp roll–off is proposed. At the beginning, the proposed NF is designed using an array of conventional Multiple Split Ring Resonator structure (MSRR), then it is replaced by modified MSRR structure in array to improve the sharpness factor in dB/GHz. This array of modified MSRR structure is behaving like a metamaterial unit cell. The proposed NF operates at resonant frequency of 2.56 GHz with 3 dB fractional bandwidth (FBW) of 4.68%, a roll-off factor (ROF) of 672 dB/GHz, and passband insertion loss of 0.35 dB. A parametric study has been done to obtain the relationship between the ring perimeter of the MSRR and the resonant frequency of the NF. Finally, a dual-band notch filter (DBNF) is designed by using an array of four modified MSRR structures. The EM simulated, circuit simulated, and measurement results of the proposed structure are in good agreement with each other. The proposed CPW based NF is useful for various applications like LTE (2600 MHz), Wimax (2500 MHz), and FCC ID (2.68 GHz).

A 110–170-GHz Non-Galvanic Interface for Integrating Silicon Micromachined Chips With Metallic Waveguide Systems

We report on the development of a non-galvanic transition from a silicon micromachined to metallic rectangular waveguide for use in integrated waveguide systems at D-band (110-170 GHz). This transition overcomes the limitations of current solutions that require proper ohmic (galvanic) contact between both waveguides, and thus relaxes tolerance requirements in assembly and manufacturing. The transition uses an in-plane design which enables low-loss integration of micromachined waveguide components, as it eliminates the need for waveguide bends and complex multi-layer structures. We describe the RF design, analyze the EM simulation results, and explain the operating principle of the transition. To verify the concept, dedicated silicon micromachined and metallic waveguides are designed and fabricated. Characterization of the assembled samples shows good agreement with simulation. The transition achieves a typical insertion loss of 0.3 dB and return loss above 20 dB over most of the D-band. Measurement of multiple samples and repeated assemblies results in a variation of S21 of less than ±0.1 dB over the whole band, demonstrating good robustness and repeatability. By removing the need for galvanic connection, automated tools can then be used during system assembly, which enables industrial scale applications such as wireless communications.

Millimeter-Wave Ultra-Wide Band Superconductor Contiguous Triplexer

This paper demonstrates the feasibility of an ultra-wide band superconductor millimeter-wave triplexer. The triplexer covers the frequency range from 20 GHz-80 GHz offering three contiguous channels, each with a 20 GHz bandwidth. The triplexer is realized using a multi-layer niobium process with a physical size of 3.6 mm × 2.5 mm. The measurement results are in very good agreement with the EM simulation results. To our knowledge, this is the first ultra-wide band millimeter-wave superconductor triplexer ever reported.