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In this paper, a broadband wide-angle leakywave antenna (LWA) with low sidelobe levels (SLL) is proposed. The antenna is composed of two parts: a broadband wide-angle scanning spoof surface plasmon polariton (SSPP)-fed circular patch antenna array and electromagnetic bandgap (EBG) structures tiled on both sides of the antenna array. By controlling the coupling distances between the circular radiation patches and SSPP feeding line, the attenuation constant along the radiation aperture is specially designed in a tapered way to achieve low SLL. EBG structures are adopted to reduce the back-lobe levels. Measured results show that the scanning angle of the proposed antenna reaches 82?. The measured realized gains are from 8 to 15.7 dBi in the operating frequency range from 8 to 12 GHz, with a maximum SLL less than -15 dB. The wide-band wideangle SSPP-fed LWA with low SLL can find applications in radar detection and microwave imaging. [ABSTRACT FROM AUTHOR]

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Maintaining the compact form of 5G smartphones while accommodating millimeter-wave (mm-wave) bands is a significant challenge due to the substantial frequency difference. To address this issue, we've introduced an super-compact 4-port dual-band multiple-input, multiple-output (MIMO) antenna that utilizes a metamaterial-inspired electromagnetic bandgap (EBG) structure. This design minimizes mutual coupling (MC) and handles a wide frequency range effectively. The 4-port MIMO antenna is constructed on a Rogers TMM4 substrate, with overall dimensions of 17.76 × 17.76 mm². It incorporates four planar patch antennas positioned at the corners, arranged perpendicularly to each other. Each antenna element is designed for dual-band operation at 28/38 GHz, featuring a rectangular patch with four rectangular slots and a full ground plane. The gap between these patches measures 0.5 λo, and an EBG is included to minimize MC among the MIMO antenna elements efficiently and cost-effectively. Both simulation and measurement results show a substantial reduction in mutual coupling between the array elements, ranging from −25 to −90 dB. Consequently, this enhances the envelope correlation coefficient (ECC) and improves the total active reflection coefficient (TARC), mean effective gain (MEG), and diversity gain (DG). An in-depth time-domain analysis is proposed to confirm the radiation efficiency of the proposed MIMO antenna design. Furthermore, specific absorption rate (SAR) analysis affirms the suitability of this MIMO antenna for 5G cellular devices operating within the target frequency band. [ABSTRACT FROM AUTHOR]

A compact WLAN band-notched reconfigurable wideband antenna using two mushroom-like electromagnetic band-gap (EBG) structures is proposed in this paper. It is designed based on a dual wideband microstrip feed patch antenna with operating frequency bands of 2.2-3.7 GHz and 4.8-6 GHz. One of the EBG cells is positioned alongside the feed line, while the other EBG cell is laid on the back of the substrate. The patch or ground of the two EBG units are fed with a stronger current through a ground slot and a parasitic stub respectively, and the connections between the EBG structures and the antenna are controlled by loading a PIN diode with two 56 pF DC blocking capacitors. The advantage of this proposed design is that the antenna and the EBG unit can be designed independently. The proposed antenna has an overall size of 35×46×1.6 mm3. When testing the S11 of the antenna, the influence of the bias circuit on the antenna is also considered. The measured results show that the proposed antenna can generate two notched bands of 2.3-2.49 GHz and 5.11-5.51 GHz of WLAN, and the realized gain in the notch bands can be reduced to -2.65 dBi and -4.55 dBi, respectively, demonstrating its anti-interference characteristics, and can be applied in band notch broadband communication systems or anti-interference communication equipments such as unmanned aerial vehicles and radars. [ABSTRACT FROM AUTHOR]

A deep neural network (DNN)-based method is proposed for the fast synthesis of a high-dimensional electromagnetic bandgap structure (HD-EBG) suppressing the power/ground noise in high-speed packages and printed circuit boards (PCBs). In recent EBG structures, a highly flexible design with high dimensionality is required, which is challenging to rapidly achieve an optimal solution. The proposed synthesis method is developed to solve this issue efficiently. The DNN hyperparameter optimization (HPO) associated with the HD-EBG structure is devised using the orthogonal array of the Taguchi method. By using this approach, the search space for HPO is reduced. For the efficient synthesis of the HD-EBG structure, an inverse modeling approach based on a DNN forward model and genetic algorithm optimization is proposed. The proposed DNN inverse modeling (DIM) is applied to two design examples where the HD-EBG structures with a constant fractional bandwidth and stopband bandwidth extension are synthesized. In the demonstration cases, the proposed DIM achieves the fast and accurate synthesis of the HD-EBG structures compared to the conventional method. With the proposed method, the synthesis time is maximally reduced up to 99.8% compared to conventional synthesis based on the forward model of full-wave simulation. [ABSTRACT FROM AUTHOR]

In this work, a multi-layered rectangular microstrip antenna, with an inset feeding technique, is designed. It consists of a 10 GHz resonating conventional microstrip patch and a novel 9 × 9 electromagnetic bandgap (EBG) array printed on a 0.5 mm thin FR-4 epoxy as superstrate; an air-spacer separated both. The top radiating patch is magnetically coupled with the bottom radiator such that it also radiates. The bottom dielectric layer's other side is finished with the perfect ground for minimizing the back-lobe radiation. The dimensional parameters are optimized for both patch and the EBG surface in the Finite Element Method (FEM)-based EM solver ANSYS HFSS. The superimposition of the top EBG surface improves the gain without degrading the performance of the lower patch. This antenna has a −10 dB reflection bandwidth of 1.2 GHz with −30.57 dB minimum reflectivity at 9.9 GHz (better VSWR). The proposed prototype offers a gain of 9.45 dBi in both E and H planes. Finally, the device is fabricated using the conventional PCB technology. The performances of the device, like gain and radiation pattern, are measured in the anechoic chamber. It is found that the simulation and measured results are in near agreement. The physical dimensions of the proposed antenna are 55 mm × 55 mm × 17.67 mm. [ABSTRACT FROM AUTHOR]

Optimization of hyperparameters of artificial neural network (ANN) usually involves a trial and error approach which is not only computationally expensive but also fails to predict a near-optimal solution most of the time. To design a better optimized ANN model, evolutionary algorithms are widely utilized to determine hyperparameters. This work proposes hyperparameters optimization of the ANN model using an improved particle swarm optimization (IPSO) algorithm. The different ANN hyperparameters considered are a number of hidden layers, neurons in each hidden layer, activation function, and training function. The proposed technique is validated using inverse modeling of two meander line electromagnetic bandgap unit cells and a slotted ultra-wideband antenna loaded with EBG structures. Three other evolutionary algorithms viz. hybrid PSO, conventional PSO, and genetic algorithm are also adopted for the hyperparameter optimization of the ANN models for comparative analysis. Performances of all the models are evaluated using quantitative assessment parameters viz. mean square error, mean absolute percentage deviation, and coefficient of determination (R 2). The comparative investigation establishes the accurate and efficient prediction capability of the ANN models tuned using IPSO compared to other evolutionary algorithms. [ABSTRACT FROM AUTHOR]

Subgridding unconditionally-stable finiteelement time-domain method based on spatial modes filtering (SSMF-FETD) is combined with the Floquet theorem and used to analyze the transmission characteristics of 2-D dielectric pillar-array electromagnetic bandgap (EBG) structures with cross-section shapes of square and H. The computational stress is effectively reduced by exploiting the periodicity of the EBG structure and subgridding technique. Through the spatial modes filtering (SMF) method, the subgridding FETD (S-FETD) method is developed into the SSMF-FETD with larger time steps and higher computational efficiency. The effect of geometric and electromagnetic parameters on transmission characteristics of EBG structures are analyzed and compared in detail, the conclusions are as follows: the optimal filling ratio of the dielectric squarepillar EBG structure is 0.5, the composite H-pillar EBG structure has multiple bandgaps and can effectively save metal materials while satisfying the design requirements. The effect of electromagnetic parameters can be uniformly analyzed from the perspective of the average relative permittivity; with its increase, the central frequency of the bandgap becomes lower. It should be noted that the bandgap distribution and variation of composite H-pillar EBG structure are related to how its dielectric parameters change and combine. The results can serve as a reference for similar structures design. [ABSTRACT FROM AUTHOR]

For the first time, liquid metal is incorporated with an elastomer platform for designing an electromagnetic bandgap (EBG)-backed wearable antenna that can be placed on human body. Here, the liquid metal (EGaIn) is injected into a soft and stretchable Ecoflex 0030 substrate for making a fluidic slot antenna and a liquid EBG (LEBG) structure. The LEBG is then placed at the back of the slot antenna for mitigating the effects of human body and improving the antenna performance. It has an antenna gain of 5.80 dBi in the boresight and a low specific absorption rate (SAR for 1 g U.S. standard) of 1.25 W/kg. Since liquid metal is highly dense, the ground plane of the LEBG is separated into six segments, which are connected through narrow bridges. Due to the use of such design, the wobbly effect of the dense liquid metal can be reduced significantly. The measured impedance bandwidth (3.23–3.59 GHz) of the proposed antenna is very stable and not affected much by its own structural deformation on human body. Since the elastomer platform is waterproof, it makes the antenna characteristics very stable in humid environment, which is a very desirable feature for wearable antennas. [ABSTRACT FROM AUTHOR]

In this study, power/ground noise suppression structures were designed based on a proposed dispersion analysis for packages and interposers with low-loss substrates. Low-loss substrates are suitable for maintaining signal integrity (SI) of high-speed channels operating at high data rates. However, when the power/ground noise is generated in the power delivery network (PDN), low-loss substrates cannot suppress the power/ground noise, thereby causing PDN-induced crosstalk and various power integrity (PI) issues. To solve these issues, noise suppression structures generating electromagnetic bandgap were proposed and designed. The mechanism of the proposed structures was examined based on a proposed dispersion analysis. The proposed structures were designed and fabricated in glass interposer test vehicles, and the effectiveness of the structures on power/ground noise suppression was experimentally validated by measuring the noise suppression band. The proposed dispersion analysis was also verified by comparing the derived noise stopband edges ( f L and f U ) with electromagnetic (EM) simulation and experimental results, and they all showed good agreement. Compared to EM simulation, the proposed method required smaller computational resources but showed good accuracy. Using the proposed dispersion analysis, various power/ground noise suppression bands were designed considering the applications and design rules of packages and interposers. With measurements and EM/circuit simulations, the effectiveness of the designed structure in maintaining SI/PI was verified. By adopting the designed structures, the noise transfer properties in the PDN were suppressed in the target suppression frequency band, which is key for PI design. Finally, it was verified that the proposed structures were capable of suppressing power/ground noise propagation in the PDN by analyzing PDN-induced crosstalk in the high-speed channel. [ABSTRACT FROM AUTHOR]

To address the issues of the inconvenient fabrication and integration for millimeter-wave (MMW) dielectric resonator antennas (DRAs), a new configuration is proposed. First, a dielectric resonator with artificial electromagnetic boundaries is implemented by introducing the electromagnetic band-gap structure along the four side-wall boundaries of a certain dielectric region on a printed circuit board. The electromagnetic bandgap (EBG) structure is constructed using a printed array of periodic upside-down mushroom-type unit cells. The resonant-mode analysis reveals that the proposed DR can support conventional dielectric resonator modes and dense dielectric patch (DDP) cavity modes simultaneously. To excite the DR, a substrate-integrated gap waveguide transmission line is embedded in the proposed structure for implementing a fully integrated DRA. For demonstration, a fully integrated dielectric resonator antenna (FIDRA) operating at 31 GHz is designed. Simulated results show that the antenna offers an 11.5% −10 dB impedance bandwidth (29.6 to 33.2 GHz), in which a peak gain of 7.85 dBi is obtained. As an extension, a multi-beam antenna array composed of a $1 \times 4$ FIDRA antenna array and a SIGW $4 \times 4$ Butler matrix is designed and fabricated. The experimental results verified the effectiveness of the proposed configuration in integrating the DRA and feeding network. [ABSTRACT FROM AUTHOR]

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make it highly favorable for wearable sensor network-based Internet of Things (IoT) applications. Considering the current need for wearable antennas, wash cotton (with a relative permittivity of 1.51) is used as a substrate material for both conventional and metamaterial-based antennas. The radiation characteristics of the conventional antenna are compared with the EBG and SRR ground planes-based antennas in terms of return loss, gain, and efficiency. It is found that the SRR-based antenna is more efficient in terms of gain and surface wave suppression as well as more compact in comparison with its two counterparts. The compared results are found to be based on two distinct frequency ranges, namely, 2.4 GHz and 5.4 GHz. The suggested SRR-based antenna exhibits improved performance at 5.4 GHz, with gains of 7.39 dbi, bandwidths of 374 MHz, total efficiencies of 64.7%, and HPBWs of 43.2 degrees. The measurements made in bent condition are 6.22 db, 313 MHz, 52.45%, and 22.3 degrees, respectively. The three considered antennas (conventional, EBG-based, and SRR-based) are designed with a compact size to be well-suited for biomedical sensors, and specific absorption rate (SAR) analysis is performed to ensure user safety. In addition, the performance of the proposed antenna under bending conditions is also considered to present a realistic approach for a practical antenna design. [ABSTRACT FROM AUTHOR]

In this paper, a small ultra-wideband (UWB) antenna with two stop bands by a compact electromagnetic bandgap (EBG) cell loaded with two new open meander slots is presented. With the coupling of the EBG cell to the feedline, the stop bands are formed. The designed EBG cell is a mushroom type that has the advantages of being able to independently control the stop bands, high responsiveness selectivity of stop bands, easy switching, the need for fewer EBG cells, and low impact on the working characteristics of the antenna. To have a better understanding of the proposed EBG mechanism, characteristic mode analysis is used. The size reduction of the suggested antenna is obtained by halving the reference antenna relative to the axis of symmetry. The measurement results for −10 dB adaptation are from 2.73 to 13 GHz with stop bands at 3.51 GHz (12.9%) and 5.34 GHz (14.1%). The radiation behavior of the minimized antenna is similar to that of a reference antenna. Minimized UWB antenna with transmission function and group delay with small variations in the operating frequency range is suitable for small multiple-input and multiple-output (MIMO) and diversity systems. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid decoupling method based on a novel electromagnetic bandgap (EBG) structure and hair-pin shaped defected ground structure (DGS) to obtain high isolation between 2-element multiple input multiple output (MIMO) antenna at 5G millimeter wave band over $27.5-28.35$ GHz. The proposed EBG designed on stacked dielectric substrates, achieves a wide frequency band-gap between $26.2-32.03$ GHz (20 %). A 2 $\times $ 3 array of the EBG is arranged between two electromagnetically coupled radiating patches in order to suppress the surface wave coupling. Substrate integrated waveguide (SIW) feeding network and cavity are strategically incorporated in the antenna design for improving the radiation performance and minimizing the losses from the feed. EBG shows an average isolation improvement of 13.9 dB within 5G band as compared to unloaded MIMO antenna. The additional reduction in coupling is achieved by placing hair-pin DGS (HP-DGS) on the ground plane, resulting in maximum isolation improvement of 47.7 dB at 27.94 GHz. The prototype of the MIMO was fabricated and experimentally verified. Measured peak isolation between the antennas is obtained as 71.9 dB, having a gain of 9 dBi and front to back ratio (FTBR) of 19.8 dB. A good diversity performance is also noticed for the designed MIMO with envelope correlation coefficient (ECC) of 0.00015, diversity gain (DG) of 9.99, and channel capacity loss (CCL) of 0.025 bits/Hz/sec. Later, SIW corporate feed network is designed for 4-element linear array loaded with EBG and HP-DGS to achieve higher gain and narrow beamwidth. The array was fabricated and the measured results are found in good accordance with the simulation results. The peak gain, beamwidth, and FTBR of the array are 13.3 dBi, 16.2°, and 19.97 dB respectively.

This paper presents a systematic study of a compact and reconfigurable periodic structure in GaAs MMIC technology. Compactness is achieved by the introduction of spiral inductors in a conventional unit cell without disturbing the reactive loading mechanism. The proposed architecture exhibits a 28.3% wider stopband with 62.6% smaller footprint compared to a conventional structure. The compactness and bandwidth improvement in the proposed structure is explained with the help of dispersion and circuit analysis. The reconfigurability built into the design using PIN diodes allows stopband switching, dual-band operation and tuning capabilities with the mere use of a single reactive load in its unit cell. To the best of the authors knowledge, it is the first time a reconfigurable MMIC implementation is realized using the proposed structure or even the conventional design. As a guide to design, sensitivity analysis to filter performance is presented for important structure parameters. Switching element parasitics are discussed in two ways: firstly, with the design and measurement of structures with idealized switching conditions and in second, with the circuit and full-wave EM modelling of the finite periodic structure with the actual PIN diodes. The on-chip measurements of the fully reconfigurable filter show excellent agreement with simulations.

This paper investigates an ultra-wideband (UWB) antenna with a triple-rectangular notch band at 5G, WLAN, and Satellite downlink bands. The 5G and WLAN bands are notched by using a pair of electromagnetic bandgap (EBG) structures while the satellite downlink band is notched by using two split-ring resonators (SRRs). The EBG structure is a metallic conductor loaded on the backside of the radiator which is connected to the patch via a shorting pin. The SRRs consist of a pair of metallic rings etched on the backside of the feedline. The simulated and measured results show that the proposed antenna has an operational bandwidth from 3.1 - 11.8 GHz for |S11|

In this paper, we design a W‐band millimeter‐wave antenna for the band of 76–81 GHz for frequency modulated continuous wave (FMCW) multiple input multiple output radar systems in automotive applications. It exhibits radiation patterns that possess narrow beamwidths with minimal beam squint in the elevation plane within the band for detection of vehicles and pedestrians in the forward direction instead of objects on the pavement and above the horizon, as well as a wide beamwidth in the horizontal plane, all as required by automotive radar antennas. A four‐port array of comb‐line antennas with diagonally tilted stubs is herein designed, the latter feature for mitigation of interruption from oncoming vehicles traveling along the opposite direction. In order to suppress the mutual interference between multiple antennas in the array, an electromagnetic band gap (EBG) structure is designed to enhance the isolation between ports. A prototype of the design was manufactured and tested, yielding results that satisfy the design requirements. Key Points: A mm‐wave antenna for the W‐band of 76–81 GHz targeted at automotive applications is presentedA four‐port array of comb‐line antennas with tilted stubs is designedA prototype of the design by simulations, which include a grounded coplanar waveguide feed network, was manufactured and measured, yielding good results [ABSTRACT FROM AUTHOR]

A novel methodology to create metallic waveguides with multilayer integrated vertical-electromagnetic bandgap (EBG) structure is proposed in this article, and the structure realizes low-cost millimeter-wave (mmWave) slot array antennas. A multilayer stack of easy-to-process thin metallic etching plates is introduced to design mmWave waveguide using compression fit instead of diffusion bonding and welding assembly process. The electromagnetic (EM) wave leakage from the gaps between the metallic plates is suppressed using the vertical-EBG structure and antiphasing feeding. The dispersion diagrams of the vertical-EBG unit cell are investigated to illustrate the suppression of leakage. Another leakage wave intercepting methodology is adopted by antiphase feeding to prevent leakage wave from the adjacent slot subarrays. Finally, two examples of 2 $\times $ 8 and 8 $\times $ 8 slot array antennas are presented to verify our design concept. The measured impedance bandwidths of the two antennas are 77.1–84.6 GHz (9.3%) and 78.6–84.9 GHz (7.7%). In addition, the 3 dB broadside gain bandwidths are 73.1–85.3 GHz (15.1%) and 76.8–84.4 GHz (9.4%). The results show the aperture efficiencies up to 56.4%. [ABSTRACT FROM AUTHOR]

For efficient and broadband noise suppression in grid-type power distribution networks (PDNs), a novel TSV-based 3-D electromagnetic bandgap (EBG) structure with an accurate and fast circuit model for predesign is proposed for the first time. The proposed structure is suitable for a silicon interposer-based system-in-package (SIP) for small size, high-density RF applications with the development of various portable terminals or other small devices. It is divided into a 3-D capacitor and a 3-D inductor, which are composed of TSVs and redistribution layers (RDLs). Profiting from the high-density integration of TSV devices, the proposed EBG can overcome the shortcomings of the existing structures, such as narrow bandgaps, large areas, and incompatibility with grid-type PDNs. The new structure effectively suppresses the simultaneous switching noise (SSN) in the interposer generated by chips or other modules. The EBG structure produces a noise suppression bandwidth (below −40 dB) of 13.22 GHz, ranging from 6.69 to 19.91 GHz with a fractional bandwidth (FBW) of 166.9%. Moreover, based on the equivalent circuit model, the bandgap of the proposed EBG can be adjusted by changing the structure parameters for diverse noise scenarios. Subsequently, to further reduce the device size, the EBG isolation wall is designed, and high performance is observed. [ABSTRACT FROM AUTHOR]

This article introduces a new type of contact-less electromagnetic bandgap (EBG) structure in the form of an embedded bed of nails. Compared with the traditional bed of nails structure, the smooth upper metal plate originally used to provide the perfect electrical conductor (PEC) boundary is replaced by periodic defect grooves, and the metal pins on the base block are embedded in these grooves without any electric contact. One of the advantages of the embedded EBG structure is that it has a robust tolerance for the height of the air gap. Therefore, this structure provides a cost-effective parallel plate mode suppression solution because it allows a low-precision manufacturing process level while maintaining the stability of the bandwidth. On the other hand, the proposed EBG structure can achieve a stopband range of several octaves. This characteristic makes it indeed suitable for wideband gap waveguides (GWs) to provide horizontal open boundaries. To verify the feasibility of the proposed approach, the new ridge gap waveguide (RGW) (with an embedded bed of nails) and the classic RGW (with a traditional bed of nails) with two 90° bends are designed, fabricated, measured, and compared. The experimental and simulation results are quite consistent and indicate that the embedded RGW has prominent advantages in bandwidth and robustness. [ABSTRACT FROM AUTHOR]

A structurally compact, semiflexible wearable antenna composed of a distinctively miniaturized electromagnetic band gap (EBG) structure is presented in this work. Designed for body-centric applications in the 5.8 GHz band, the design draws heavily from a novel planar geometry realized on Rogers RT/duroid 5880 laminate with a compact physical footprint spanning lateral dimensions of 0.6 λ 0 × 0.06 λ 0. Incorporating a 2×2 EBG structure at the rear of the proposed design ensures sufficient isolation between the body and the antenna, doing away with the performance degradation associated with high permittivity of the tissue layer. The peculiar antenna geometry allows for reduced backward radiation and low specific absorption rate (SAR). With the inclusion of EBG, the gain of the antenna undergoes a considerable increase to 7.2 dBi with more than 95% reduction in SAR value. In addition, the front-to-back ratio also amplified to 13 dB. A rigorous analysis detailing the structural robustness is reported for varied bend angle configurations of the proposed antenna. To assess the suitability of the proposed design as a body-worn antenna, an experimental investigation is carried out on different parts of the body. Experimental findings are congruent with computationally obtained results, validating the applicability of the novel antenna structure for body-worn applications. [ABSTRACT FROM AUTHOR]

In this paper, a backfire suppressed aperture coupled circularly polarized (CP) stacked patch antenna for universal ultra-high frequency (UHF) radio frequency identification applications is presented. Cross-polarized backfire radiation patterns were successfully suppressed by a planar high impedance surface (HIS) reflector. The size of the fabricated antenna is 250 × 250 × 26.9 mm3 (0.71λ0 × 0.71λ0 × 0.076λ0) and its peak gain value of 7.1 dBi is measured. The distance between the antenna and the HIS reflector is only 4.8 mm (0.014 λ0). The HIS reflector suppressed cross-pol backfire radiations by about 10 dB. Detailed antenna and HIS reflector design are discussed thoroughly in this paper. The presented backfire suppression technique using the HIS reflector is scalable to other applications and frequency bands. This paper demonstrates the feasibility of the HIS structure at UHF band. [ABSTRACT FROM AUTHOR]

A single-layer, planar wideband microstrip line (ML) fed metasurface-based antenna operating at 5 GHz wireless local area network band is proposed. It is composed of an array of $3 \times 3$ square metal patches fed by an ML connected to the central patch of the three peripheral unit cells. To reduce the phase delay between the driven patch and the parasitic patches placed along the E-plane, a large square slot is cut on the fed patch, while the patches on the second and third rows are sliced into smaller ones to stabilize the patterns at higher frequencies. The large slot also helps achieve better impedance matching. ${{\bf T}}{{{\bf M}}_{01}}$ and ${{\bf T}}{{{\bf M}}_{21}}$ modes are excited, giving a measured $ - 10{\boldsymbol{\ }}{{\bf dB}}$ bandwidth of 26.56% (5.06–6.61 GHz). The compact size of $1{{\boldsymbol{\lambda }}_0} \times 1.1{{\boldsymbol{\lambda }}_0} \times 0.058{{\boldsymbol{\lambda }}_0}$ (${{\boldsymbol{\lambda }}_0}$ is the free-space wavelength at the center of the frequency band), stable boresight patterns, low profile, planar configuration, and wide bandwidth features make the presented antenna attractive for various wireless systems. [ABSTRACT FROM AUTHOR]

This paper proposes a new concept of designing compact high precision millimeter-wave wideband variable phase shifters. The phase shifter is implemented with a stacked shim with extremely short length of 0.9 mm and two waveguide flange adaptors with length of 0.5 mm. High precision phase shifting is achieved over entire D-band (110-170 GHz) by rotating the shim 90 degrees from aligned to perpendicular with consistent impedance matching performance. In addition, a glide-symmetric holey electromagnetic bandgap (EBG) structure is adopted to avoid wave leakage from the gap between the shim and the flange adaptors. A proof-of-concept (PoC) demonstrator is designed, manufactured, and tested. The measured results show that the designed stacked shim phase shifter with embedded EBG structure ensures return loss higher than 10 dB across 110-170 GHz with a 75 μm airgap between waveguide flanges. The studied phase shifter provides a 0.88° phase shifting with each degree of mechanical rotation. The fabricated PoC phase shifter has a worst-case insertion loss of 0.92 dB and a return loss of 20 dB across the entire 110-170 GHz band and a maximum phase shift of 30°. At 10° phase shifting, the measured insertion loss is lower than 0.52 dB, and return loss is higher than 23 dB, respectively.

In this article, a planar ultra‐wideband (UWB) antenna with dual rectangular notchband characteristics (ie, 5.94‐7.50 GHz and 8.02‐10.46 GHz) is presented. The two‐notch bands are chosen based on various wireless applications operating in C‐band and X‐band. The size of the antenna is very compact (25 × 25 × 1.6 mm3) and is designed on a low‐cost FR4 substrate. Co‐planar waveguide (CPW) feed and beveling techniques are utilized for achieving the UWB operation. In order to yield the first rectangular notch, a U‐slot and a pair of split‐ring resonators are embedded into the radiating patch and the backside of the design, respectively. The coupling between these two structures is adjusted so as to achieve a rectangular band‐notch operation. The second rectangular notch has been achieved by introducing the two mushroom type electromagnetic band‐gap structures on the opposite side of the CPW feed. The parametric analysis for controlling band notches, time‐domain analysis, and filter synthesis is also presented. Finally, simulated as well as measured results of S11, gain, radiation pattern, group delay, and total efficiency are demonstrated to show the suitability of this design for UWB systems. [ABSTRACT FROM AUTHOR]

In this study, power/ground noise suppression structures were designed based on a proposed dispersion analysis for packages and interposers with low-loss substrates. Low-loss substrates are suitable for maintaining signal integrity (SI) of high-speed channels operating at high data rates. However, when the power/ground noise is generated in the power delivery network (PDN), low-loss substrates cannot suppress the power/ground noise, thereby causing PDN-induced crosstalk and various power integrity (PI) issues. To solve these issues, noise suppression structures generating electromagnetic bandgap were proposed and designed. The mechanism of the proposed structures was examined based on a proposed dispersion analysis. The proposed structures were designed and fabricated in glass interposer test vehicles, and the effectiveness of the structures on power/ground noise suppression was experimentally validated by measuring the noise suppression band. The proposed dispersion analysis was also verified by comparing the derived noise stopband edges (fL and fU) with electromagnetic (EM) simulation and experimental results, and they all showed good agreement. Compared to EM simulation, the proposed method required smaller computational resources but showed good accuracy. Using the proposed dispersion analysis, various power/ground noise suppression bands were designed considering the applications and design rules of packages and interposers. With measurements and EM/circuit simulations, the effectiveness of the designed structure in maintaining SI/PI was verified. By adopting the designed structures, the noise transfer properties in the PDN were suppressed in the target suppression frequency band, which is key for PI design. Finally, it was verified that the proposed structures were capable of suppressing power/ground noise propagation in the PDN by analyzing PDN-induced crosstalk in the high-speed channel.

This article proposes a longitudinal output structure in Ka-band sheet beam traveling-wave tube (SBTWT) with an ultrawideband transmission and high breakdown collector voltage. A novel electromagnetic bandgap (EBG) cutoff structure is designed to separate the slow-wave structure (SWS) and the depressed collector. The large stopband property of the EBG structure is applied to achieve not only the high transmission and the low gap leakage but also the long gap distance to provide a high breakdown voltage of the depressed collector. The 3-D simulations of a single longitudinal structure show a full Ka-band (26.5–40 GHz) reflection of less than −20 dB and gap leakage less than −0.02 dB. The entire longitudinal output collector, including two large gaps cutoff structures and the over mode electron collecting parts, is designed and manufactured. The simulations show a bandwidth of 10.4 GHz with a reflection coefficient S11 of lower than −20 dB. The cold test demonstrates the wild bandwidth of ~11.1 GHz with a reflection coefficient S11 of lower than −15 dB. The hot test reveals a stable collector dc voltage of −14.2 kV. [ABSTRACT FROM AUTHOR]

A Y-junction circulator based on the ridge gap waveguide (RGW) as a hosting guiding structure is designed using a developed closed-form systematic procedure. To validate the structure, an air-filled-to-dielectric-filled transition is proposed using a substrate perforation technique. The proposed RGW circulator covers the whole Ku-band with a matching bandwidth throughout the operational bandwidth below −15 dB. A prototype is fabricated and tested, providing a satisfactory agreement with the simulated results. [ABSTRACT FROM AUTHOR]

A novel millimeter-wave (MMW) hybrid isolator is presented to reduce the mutual-coupling (MC) between two closely-spaced dielectric resonators (DR) antennas at 60 GHz. The proposed hybrid isolator consists of a combination of a new uni-planar compact electromagnetic band-gap (EBG) structure and an MMW choke absorber. The design of the proposed EBG unit-cell is based on the stepped-impedance resonator (SIR) technique. The results show that the proposed EBG structure provides a wide frequency bandgap in the 60 GHz band with miniaturization factors of 0.79 and 0.66 compared to conventional uni-planar EBG and uni-planar compact (UC-EBG) structures, respectively. The proposed EBG is then placed between two Multiple-Input Multiple-Output (MIMO) DR antennas to reduce the MC level. As a result, an average of 7 dB level reduction is obtained. To further reduce the MC level, a thin MMW choke absorber wall is mounted vertically between the two DR antennas and above the EBG structure. An average of 22 dB MC reduction is achieved over the suggested bandwidth while maintaining good radiation characteristics. The measured isolation of the prototype antenna varies from -29 to -49 dB in the frequency range from 59.3 to 64.8 GHz. In fact, the proposed hybrid isolator outperforms other hybrid isolation techniques reported in the literature.

A 1-D phased array based on a dual-artificial magnetic conductor (AMC) ground is proposed in this letter. Initially, the relationship between the reflection, radiation, and scattering performance of the AMC-based phased and the AMC properties are investigated. Based on the analysis, a hybrid AMC ground is designed with wide zero-phase and anti-phase reflection bandwidths and electromagnetic bandgap characteristics. An eight-element-phased array is then presented. The wideband wide-angle scan is realized by the image theory and bandwidth enhancement of the element antenna, and the wideband low-radar cross section (RCS) performance is obtained by scattering cancellation. Experimental results indicate that the designed phased array support a scan up to 60° in an active reflection band (VSWR < 3) of 7.5–10.8 GHz and the RCS reduction from 12.0 to 16.0 GHz for TE polarization and from 10.8 to 15.2 GHz for TM polarization, respectively. [ABSTRACT FROM AUTHOR]

A compact double-sided contactless electromagnetic bandgap (DCEBG) structure is introduced in this letter. It consists of three metal plates placed in parallel, including two smooth metal plates and a corrugated metal plate in the middle. The middle plate is double-sided corrugated alternatively with a displacement of half period. The depth of the corrugations is about quarter wavelength of center frequency of its stopband. The thickness of the proposed DCEBG is slightly thicker than the depth of the corrugations. A double-sided contactless waveguide flange (CWF) based on the DCEBG is proposed. Compared with the back-to-back CWF in the form of bed of nails, the thickness is effectively reduced. A prototype of the double-sided CWF (DCWF) suited for standard WR75 waveguide is designed, manufactured, and tested. The measured insertion loss is less than 0.048 dB and the return loss is lower than 25 dB over the entire WR75 waveguide frequency band. [ABSTRACT FROM AUTHOR]

In this article, we propose a double-sided electromagnetic bandgap (DS-EBG) structure for glass interposers (GIs) with low substrate loss to suppress power/ground noise. For the first time, we validated wideband power/ground noise suppression in the GI using the proposed DS-EBG structure based on dispersion analysis and experimental verification. We experimentally verified that the proposed DS-EBG structure achieved the power/ground noise suppression (below −40 dB) between 2.5 and 8.9 GHz in the GI. Derived stopband edges, $f_{L}$ and $f_{U}$ based on the dispersion analysis, and 3-D electromagnetic (EM) simulation showed a good correlation with measurements. The effectiveness of the proposed DS-EBG structure on the power/ground noise suppression is verified by analyzing noise propagation in the power distribution network and coupling to the GI channel. Using the 3-D EM simulation, we verified that the proposed DS-EBG structure suppressed the power/ground noise coupling and improved the eye diagram of the GI channel. Finally, we propose a design methodology to broaden the isolation bandgap or miniaturize the dimensions based on the dispersion analysis. [ABSTRACT FROM AUTHOR]

In this work, directly perforated substrate integrated waveguides (SIWs) in the form of periodic air holes are studied with a focus on the electromagnetic shielding effect by examining its bandpass and stopband filtering characteristics. Two different configurations of the air-filled holes are considered for this electromagnetic bandgap structure, which are called shielded and unshielded cases. In both the scenarios, the relationship between the center frequency of the bandgap and the structural material and geometric parameters is established and used for the bandgap investigation. In addition, the impact that the shielding of the air-filled holes yields on the loss of the structure is systematically examined. Finally, equivalent circuits for both the cases are formulated and experimentally verified up to 30 GHz. [ABSTRACT FROM AUTHOR]

In this article, impedance mismatch effects on the characteristics of common-mode (CM) electromagnetic bandgap (EBG) filters are studied using three-dimensional (3-D) full-wave numerical simulations. The CM EBG filters considered herein are designed using standard printed circuit board technology and contain either microstrip (MS) differential pairs running above the EBG plane, or stripline (SL) differential pairs running on one of the layers next to the EBG plane. First, the terminations are fixed at 50 Ω, and the effects of the differential line impedance variations on the EBG filter parameters are studied. Overall, the considered variations in the widths of the traces and edge-to-edge separation distances in both the MS and SL structures do not drastically deteriorate the performance of the EBG CM filters. Then impedances of the ports are set different from 50 Ω, and the effects of this mismatch on the baseline SL and MS EBG structures are studied. It is shown that lower port impedances may have significant effect on the characteristics of filters. In addition, baseline EBG filters are cascaded with unmatched four-port load, and this may also deteriorate performance of filters. [ABSTRACT FROM AUTHOR]

In this article, the concept of radiative bandpass filter (RBPF) is proposed and investigated for developing a class of multifunctional filtering leaky-wave antennas (LWAs) which exhibit the simultaneous rapid frequency-dependent beam-scanning and frequency-selective characteristics. A substrate-integrated waveguide (SIW) is periodically loaded with closed (nonradiative) discontinuities acting as a bandpass filter, where the lower and higher stopbands are, respectively, stemmed from the SIW natural cutoff and the Bragg effect bandgap or bandstop caused by periodic discontinuities. By adequately adjusting the periodicity of filter unit cells and loading effects of closed discontinuities, filtering and dispersion behaviors of the periodic SIW can be flexibly engineered. Open (radiative) discontinuities are then deliberately introduced into the bandpass filter to generate a controllable radiation leakage, thereby accomplishing the design of the RBPF, i.e., the proposed LWA. With this concept, both filtering/dispersion and radiation tasks can be independently managed by different modules for LWAs. For demonstration purposes, two kinds of closed discontinuities, namely nonradiative longitudinal slot-pair (capacitive) and iris (inductive), are separately exploited for periodic SIWs with bandpass and high dispersion characteristics, whereas transverse slot (open discontinuity) is mainly aimed for radiation leakage. Two RBPF-based LWAs are simulated, fabricated, and measured. The simulated and measured results are in a reasonable agreement, and both demonstrate the rapid beam-scanning and filtering behaviors, thereby validating the proposed concept. [ABSTRACT FROM AUTHOR]

A slow-wave substrate integrated groove gap waveguide (SW-SIGGW) is presented for the first time in this letter. The developed SW-SIGGW consists of three stacked substrate layers with different thickness, in which asymmetric half-height mushroom-type electromagnetic bandgap (EBG) structures are utilized for the convenience of tuning the heights of each layer. The slow-wave effect is achieved by loading periodical metallic via holes inside the groove gap waveguide in the bottom layer separating the magnetic and electric fields. In both lateral and longitudinal dimensions, 41% reductions are achieved through this new topology of SW-SIGGW, since the guided wavelength decreases significantly compared to the normal SIGGW of same width and height. A prototype of the SW-SIGGW is designed, manufactured, and measured. The simulated and measured results are in good agreement, proving the validity and feasibility of the design. [ABSTRACT FROM AUTHOR]

Mushroom-type electromagnetic bandgap (EBG) structures are known to operate as high-impedance surfaces at low-frequency bands. They are broadly used in the microwave regime. However, one of the main drawbacks of mushroom-type EBG structures is their narrow bandwidth. In this article, we propose a mushroom-type EBG structure with glide-symmetric edge vias to increase the operational bandwidth. This bandwidth increment is explained by the physical insight provided by an equivalent circuit model of the structure as well as the description of the field behavior. Simulation and measurement results show an improvement of approximately 67% over the case without glide symmetry in the structure. We conclude that applying glide symmetry to the mushroom-type EBG structures can improve their bandwidth without adding additional manufacturing costs. [ABSTRACT FROM AUTHOR]

This work explores how growth simulation may be applied to the fundamental area-to-point (AP) optimization problems in the design of integrated circuits. To achieve this, a newly developed generative algorithm capable of creating a continuous explicit tree-like path is applied. Novelty of the proposed algorithm lies in the introduction of a specific interpolation scheme called “electrical conductivity spreading approach”, which enables conducting channels to extend freely without constraint by the underlying finite element mesh (i.e., node locations or element connections); thus, more optimization flexibility is achieved compared to the previous constructal methods. To demonstrate the benefits of this method for AP problems, two optimization models with different objective functions are exemplarily benchmarked against a conventional constructal design for power distribution networks (PDNs) in electromagnetic bandgap (EBG) power planes. In each case, the optimization finds a significant improvement with respect to the conventional design. Good agreement between experimental measurements and simulations is found, which confirms the validity of the proposed generative algorithm. [ABSTRACT FROM AUTHOR]

We propose a metasurface (MTS) structure integrated at the aperture of a flanged rectangular waveguide to produce dual-beam radiation. The dual beams are antiparallel in an orientation and perpendicular to the boresight direction. The MTS is backed by a dielectric slab to produce a substrate integrated waveguide-like response above the flange. The MTS is engineered to limit the boresight emission from the waveguide aperture, as well as to allow symmetric wave splitting between the MTS and waveguide flange. A lens-like end texturing involving surface tapering and electromagnetic bandgap cells is utilized to enhance the beam directivity at endfire from the flange. The dual-beam radiation exists for all frequencies between 10.5 and 12.4 GHz. The proposed design is modeled via full-wave simulation in commercial software, then validated through the measurement of a fabricated prototype. [ABSTRACT FROM AUTHOR]

An anisotropic impedance surface based on electromagnetic bandgap (EBG) theory is proposed to produce reconfigurable dual-beam radiation through surface-wave (SW) lensing by controlling SW propagation across the surface-to-air interface. The reconfiguration of the lensing effect is triggered by switching between 4.0- and 4.5-GHz frequencies, utilizing the anisotropy of the impedance surface created from two mutually exclusive EBGs along the two orthogonal spaces. The bandgaps are formed by a periodic arrangement of two different split-ring resonators (SRRs) with bandgaps at around 4.0 and 4.5 GHz along the orthogonal $y$ - and $x$ -axes, respectively, producing a strong axially symmetric anisotropy. As a result, a surface-bound wave, i.e., both transverse electric (TE) and transverse magnetic (TM), faces asymmetric propagation reluctance toward these two directions one of which is very high compared to the other at frequencies around the individual bandgaps of the unit cells. The proposed impedance surface is designed and simulated using commercial electromagnetic simulation software and then fabricated and measured to validate the model. [ABSTRACT FROM AUTHOR]

In this article, a novel automatically designed electromagnetic bandgap (EBG) structure is presented to prohibit the simultaneous switching noise (SSN) propagation of a system in package. The tool employed for the automatic EBG design is the improved genetic algorithm (GA), which has the advantages of rapid convergence and high precision by combining several improvements reasonably. Meanwhile, the equivalent circuit model and the dispersion diagram of the proposed structure are established to interpret the electromagnetic characteristics of the designed power distribution network (PDN). By removing some patches in a specific area determined by the GA, the surface impedance of PDN can be increased to reduce the SSN coupling. The SSN transmission can be suppressed from 0.37 to 20 GHz at a mitigation level of −50 dB. The measured results agree well with the simulated ones. [ABSTRACT FROM AUTHOR]

A low-profile, high-gain, and broadband U-slot cut artificial magnetic conductor (AMC) loaded patch antenna is presented in this letter. The wideband performance is achieved by strategically cutting two rectangular slots and inserting four strips onto a conventional AMC ground plane. Moreover, a defected ground structure is used to reduce the antenna size. As a result, four reflection zeroes are obtained within the antenna | $S_{11}$ | curve. The antenna is characterized by a low profile ($\boldsymbol{h}/{\boldsymbol{\lambda }_0}\sim 0.05$ , ${\boldsymbol{\lambda }_0}$ is the free-space wavelength at the center frequency), wide bandwidth 58.6%, light weight, low cost, and wide 10 dBi gain bandwidth. The presented antenna is suitable for C-band satellite (3.7–4.2 GHz), 5.15–5.35 GHz WLAN, and the 5G in 3–6 GHz band applications. [ABSTRACT FROM AUTHOR]

A novel swapped double-sided electromagnetic bandgap (DS-EBG) power/ground plane is proposed with broadband suppression of the simultaneous switching noise (SSN) and low radiation emission. By using the double-sided structure, the equivalent inductance between the EBG cells can be well improved and result in the broadband suppression of SSN. In the proposed structure, pairs of via are used to build the three-dimensional bridges between the swapped power/ground planes. They also lead to the suppressions of SSN be improved. Simulated and measured results show good agreements with each other. Additionally, the measured radiation emission of the proposed structure shows that it has lower electromagnetic interference compared with the two typical reference boards. [ABSTRACT FROM AUTHOR]

Several electromagnetic bandgap (EBG) structures have been designed to mitigate simultaneous switching noise (SSN) problems in dual bands in wireless local area networks (WLANs). In order to be applicable to two-layer printed circuit boards (PCBs), a novel flipped structure is introduced, which also creates slots for a wide stopband. This article proposes a $2 \times 2$ nonperiodic flipped-EBG (FEBG) for dual-band SSN mitigation in the WLAN, exhibiting noise suppression of 21 and 26 dB in 2.4–2.6 and 5–6 GHz bands, respectively. The simulation results are in good agreement with the experimental data. In addition, a method of positioning optimization is introduced as well to demonstrate the application of the FEBG on a two-layer PCB. [ABSTRACT FROM AUTHOR]