Electromagnetic Bandgap Cells Research Articles

Design and verification of an umbrella shaped narrow band - UWB antenna pair for MIMO applications using characteristic mode analysis

Using characteristic mode analysis (CMA), a pair of ultra-wideband (UWB) and narrow band antennas is made. The Multiple Input Multiple Output (MIMO) configuration incorporates a circular monopole to attain UWB functionality, while an umbrella-shaped element generates the narrowband operation. The two radiators are symmetrically positioned to accomplish space diversity. Distinct sizes of small electromagnetic band gap cells separate the two radiators. The MIMO structure has dimensions of 40×40×1.6 mm3 (0.32λo×0.32λo×0.12 λo) and improved isolation is accomplished by adding a T-shaped stub to the ground plane. The exceptional bandwidth of 11.6 GHz offered by the Circular-pot UWB antenna covers a frequency range from 2.4 GHz to 14 GHz. The antenna demonstrates favorable MIMO performance, featuring a gain of 4.9dBi, isolation exceeding 23 dB. The diversity characteristics encompass an enveloped correlation coefficient (ECC) of under 0.0012, a diversity gain (DG) approaching 10 dB, a channel capacity loss of 0.28 b/s/Hz, and a mean effective gain (MEG) measuring -3.3 dB. A favorable agreement between the tested and simulated results.

Design of a Reconfigurable Band-notched Wideband Antenna using EBG Structures

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.

Size Reduction and Harmonics Suppression in Microwave Power Dividers

In this paper, several types of microstrip power divider are studied and compared in terms of harmonics suppression and size reductions. The importance of this research lies in the fact that power dividers are critical components in various communication systems, and their performance directly affects the overall system efficiency. The conventional structure of the power divider has an acceptable performance at operating frequency in terms of excellent output ports isolation, low insertion loss, and high return loss, but occupies large size and passes unwanted signals at higher frequencies along with desired signal without any suppression. Harmonics are popular distortion and has different distortion impacts in many different facilities. Recently, several techniques are introduced to overcome these drawbacks. Applied open stubs, applied resonators, lumped reactive components such as capacitors and inductors, coupled lines, defected ground structure (DGS), and electronic band gaps are common methods, which are widely used to overcome these drawbacks. Finally, the study results show that the resonator-based power dividers and coupled-line-based power dividers have good performances in terms of size reduction and harmonic suppression but increase insertion loss parameter. Furthermore, the lumped reactive component-based power dividers and applied DGS and electromagnetic bandgap cells suppress unwanted harmonics, but they need extra process to fabrication, which is undesirable. Moreover, the open-stub-based power dividers have moderate performance with simple structure, but size reduction and harmonics suppression are not so superior in this method.

Design of a Low Profile Archimedean Spiral Antenna using Compact Defected Ground Structure as a Reflector

In this paper, design and realisation of a low profile Archimedean spiral antenna is presented. The low profile Archimedean spiral antenna is printed on a substrate and backed by a reflector consisting of DGS. The DGS unit cell consists of a parallel combination of meander line inductors and inter-digital capacitors. This, DGS is one of the forms of electromagnetic band gap (EBG) structures providing electromagnetic band gap characteristics. It is used as a reflector with spiral antenna to achieve unidirectional radiation properties and a low profile of antenna. A modified version of uniplanar EBG cell is used as a DGS cell. This cell is used for configuration of the DGS ground plane. This ground plane is evaluated for its electrical characteristics and used as a reflector for the spiral antenna. Archimedean Spiral antenna is designed and simulated in the frequency band of 1-6GHz with DGS as a reflector. The antenna characteristics are studied for physical parameters of the antenna. These parameters are optimized for better electrical characteristics. The performance of the proposed antenna is also compared with conventional metallic (PEC) reflectors. Simulated results of an antenna are validated by measurement. Antenna height reduction of 60% is achieved compared to conventional cavity-backed spiral antennas.

A new hybrid method for mutual coupling minimization of an antenna array

<span lang="EN-US">In this paper, a simultaneous application of geometric modification on patch elements and electromagnetic band gap (EBG) electromagnetic bandgap structures (hybrid method) has been suggested for 3.5 GHz wireless communication applications, to minimize the mutual coupling between radiating elements of microstrip array antennas. The suggested EBG slotted structure is composed of a one square ring and three squares placed on Rogers RO3010 having 10.2 and h=1.27 mm which presents respectively its dielectric constant and thickness. In this approach, the patch elements are geometrically modified, while also employing EBG structures, formed by four EBG cells, placed between the array elements at a near distance. The modification of the geometry of the antenna and the introduction of EBG reduces the mutual coupling of an array antenna with approximately 33 dB on the one hand and improves the antenna gain by approximately 0.43 dB on the other hand. Initially, slots are introduced in the patch geometry and then four EBG unit cells are inserted between two patches, operating at 3.5 GHz. The antenna array design parameters were optimized.</span>

Multi-Mode Excitation by Interleaved EBG Structure for Suppression of Power/Ground Noise in Multi-Layer PCBs

Signal line transition with layer transition via is inevitable in multi-layer PCB. The return current can generate voltage noise between the cavities due to the discontinuity of the return current path. Other layer transition vias passing through the cavity can pick up the voltage noise and result in problems of signal integrity. In this paper, an electromagnetic bandgap (EBG) structure is proposed for suppression of the broadband cavity noise. The impedance discontinuity between layers of interleaved EBG cell enhances the efficiency of noise suppression, and the slots embedded in the EBG cell excite multi-mode resonances for extending the bandwidth of noise suppression. The dispersion diagram is utilized to preliminarily analyze the characteristic of the proposed EBG cell, and a 5×5 cells EBG board is further analyzed for characterizing the efficiency of noise suppression. Both simulation and measurement results prove the proposed structure can effectively suppress the cavity noise under −35 dB over the frequency range from 0.56 GHz to the highest measurement frequency, 20 GHz.

Designing of Unit EBG Cell Using Conductive Textile for Dual Band Operation

Background/Objectives: Flexible electronics have paved the way for Wireless Body Area Networks (WBAN). The main challenge in accommodating such applications is reducing the impact of radiation on the human body. The presence of body tissues may affect WBAN devices such as wearable sensors and wearable antennas, so reducing back radiations becomes an important task. Methodology: When a microstrip patch antenna is placed on a human body, the artificially formed Electromagnetic Band Gap (EBG) surface mimics the property of a Perfect Magnetic Conductor (PMC) rather than the conventional Perfect Electrical Conductor (PEC). Findings: In this work, the unique property of the EBG surface beneath the patch antenna creates a zero phase shift at the resonance, which improves the antenna’s performance and reduces back radiations as well. The proposed EBG surface structure is the simplest square-shaped structure with no conductor connections Via patch (Via-less). Novelty: The EBG structure designed and presented in this paper has zero reflections for the dual-band of operations. The resonance frequency of 2.45GHz and 5.5 GHz has been designed for the absorption of 80% and 65% respectively. This level of absorption has not yet been reported in the literature. The newly formed EBG cell integrated with the patch antenna and its performance improvements has been shown. The analysis shows that the EBG enhances the return loss by 20.35 % and gain enhances by 16.44 %, on textile materials with the advantage of most simplex EBG cell construction. Keywords: EBG; PMC; PEC; Wearable Microstrip Patch Antenna; WBAN

Planar EBG Loaded UWB Monopole Antenna with Triple Notch Characteristics

A triple band-notched ultra-wideband (UWB) monopole antenna using a planar electromagnetic bandgap (EBG) design is proposed. The EBG unit cell composed by an Archimedean spiral and inter-digital capacitance demonstrates the notch frequencies. The antenna with EBG cells near the feed line occupies only 30 × 36 mm2 with triple band-rejection characteristics. The three notched bands at 4.2 GHz, 5.2 GHz, and 9.1 GHz can be used in C-band satellite downlink, wireless local area network (WLAN), and X-band radio location for naval radar or military required applications. In addition, the proposed design is flexible to tune different notched bands by altering the EBG dimensions. The parametric analysis is studied in details after placing the EBG unit cells near the feed line to show the coupling effect. The input impedance and surface current distribution analysis are also analyzed to understand the effect of EBG at notch frequencies. The proposed design prototype is fabricated and characterized. A fairly considerable agreement is observed between simulated and measured results.

Small UWB antenna with two stop bands by a compact EBG cell loaded with new open meander slots

AbstractIn 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.

SAR reduction and gain enhancement of compact wideband stub loaded monopole antenna backed with electromagnetic band gap array

This article discusses a design of compact wideband stub loaded monopole antenna (CWSLMA) backed with 3 × 3 array of hexagonal shaped electromagnetic band gap (EBG) cell operating at 2.45 GHz with enhanced gain and low specific absorption rate (SAR) for wireless body area network (WBAN) applications. The split ring rectangular shaped radiator is designed with protruding stub to miniaturize the antenna size of monopole antenna (34 × 18 × 1.6 mm3) at resonance frequency 2.45 GHz. The proposed CWSLMA is fabricated on glass epoxy FR4 substrate supported with 3 × 3 array of hexagonal shaped EBG cell over Kapton polyimide flexible substrate. The proposed antenna consists of simulated 10 dB return loss (RL) bandwidth (BW) of 16.7% (2.3–2.72 GHz). The proposed 3 × 3 array of hexagonal shaped EBG cell enhances the realized gain of proposed CWSLMA to 7 dBi by reducing the back-lobe radiation. The EBG array also increased the isolation between fabricated wearable antenna and human body and thus, reduced SAR to 0.44 W/kg (tested over 10 g of human tissues) at frequency 2.45 GHz. The fabricated proposed CWSLMA with EBG achieved a measured 10 dB RL bandwidth of 17.3% (2.27–2.7 GHz) and a measured group delay below than 1 ns in entire operational band with measured gain of 6.8 dBi. The proposed CWSLMA with EBG is designed, fabricated, and tested. The measured results of fabricated antenna prototype are verified and validated with simulated ones.

UWB dual-notched planar antenna by utilizing compact open meander slitted EBG structure

In this paper, an ultra-wideband (UWB) dual-notch planar antenna is presented. The antenna, in its structure, utilizes a compact electromagnetic bandgap (EBG) structure with new open meander slits to notch two frequency bands at around 3.5 and 5.5 GHz. The main idea is to place the new slitted mushroom-type EBG structure at the vicinity of the feedline to achieve filtering ability for the antenna. The presented EBG structure has many benefits, like notched bands with sharp roll off, independent control over the notched bands, little effects on antenna performance, easy switching configuration and reduction of the required number of EBG cells. The fabricated antenna shows −10 dB bandwidth of 2.63 up to 13 GHz with dual-notched in the frequency bands of 3.11–4.01 GHz and 5.15–5.98 GHz. Simulation and experimental results exhibit a close agreement with each other. The proposed UWB antenna with a flat transfer function and a constant group delay at the notched bands is a suitable choice for compact UWB communication systems.

Compact multiple electromagnetic band gap (EBG) cells based ultra wide band (UWB) filter with improved stop-band characteristics

PurposeThe purpose of the study is – in Microwave filter design, the performances of passive components are deteriorated by parasitics at gigahertz (GHz) frequency range. A compact and multi-stack electromagnetic band gap (EBG) structure is proposed with improved stop band characteristics at GHz frequency range in this work. This paper proposes a new design for ultra wide band pass filter (resonator BPF) with periodically loaded one-dimensional EBG to achieve the harmonic suppression. This basic EBG structure is developed with combination of a signal strip and ground plane in the slotted section. The resonator BPF is loaded with one EBG, two EBG and three EBGs to improve the stop-band rejection.Design/methodology/approachThe proposed filter is with multi-stack EBG cell for achieving good pass band and stop bands performance. Circuit model is analyzed in Section 2. Section 3 discuses band pass filter loaded with one EBG. In Sections 4 and 5, filter with two and three EBG loaded resonators are discussed, respectively. Section 6 is concluded with comparison of simulation and measured results.FindingsThe stop-band rejection is 20 dB, 40 dB and 50 dB, respectively, in the frequency range of 6 GHz to 20 GHz. The simulation analysis is carried out with advanced system design software. To validate the simulation results, proposed structure is fabricated, and results are found to be in good agreement.Originality/valueThis paper accounts for designing resonator BPF, which has slow wave pass band and stop band characteristics. Second and third harmonics are suppressed using multi-stack EBG. Various stacks with basic designs are proposed and improved results have been demonstrated which is open for future research.

Wearable textile EBG‐inspired bandwidth‐enhanced patch antenna

An electromagnetic bandgap (EBG)-inspired low-profile wideband textile antenna is presented. By partially surrounding a standard textile patch antenna with mushroom EBG cells, a significant enhancement of the 10 dB impedance bandwidth is obtained. In particular, whereas a standard textile patch antenna exhibits a typical 10 dB bandwidth of 6% for a substrate thickness of 0.04, the proposed technique extends the 10 dB impedance bandwidth to 32%. Notably, the relatively large impedance bandwidth is achieved without extracting a heavy cost in terms of fabrication or design complexity. To make the design amenable for textile implementation, as opposed to more conventional designs which use EBG cells as a replacement for a ground plane, the proposed design hinges on the patch antenna being coplanar with a single quasi-ring of coplanar EBG cells. The proposed antenna design is validated through measurements in free space and on-body, where it is demonstrated to be robust to the effects of bending in the two principal planes.

Compact multiple EBG cells loaded UWB-narrowband antenna pair with high isolation for cognitive radio (CR) based MIMO applications

In this paper, a cognitive radio (CR) based multiple-input-multiple-output (MIMO) antenna element comprising of an ultra-wideband (UWB) and narrowband (NB) radiator is proposed. The antenna consists of a circular monopole to achieve UWB operation and a quarter-wavelength monopole for NB operation. The high isolation between the two radiators is obtained by accommodating multiple electromagnetic band-gap (EBG) cells and an isolating stub between the UWB and NB radiators. Multiple EBG cells of varying size are employed to obtain isolation-enhancement over the entire UWB spectrum. The proposed design exhibits high isolation, better than 25 dB over most of the UWB spectrum. Fabricated prototype was measured and compared with simulations and good agreement was obtained. The antenna also satisfied the MIMO performance metrics. The size of the antenna is 50 × 50 mm2. Proposed highly isolated MIMO antenna pair is a good candidate for multi-standard radio applications requiring wideband and narrowband antennas in the same platform.

Printed compact asymmetric dual L‐strip fed split‐ring shaped EBG‐based textile antenna for WBAN applications

AbstractThis letter presents a design of very compact asymmetric dual L‐strip fed split‐ring shaped electromagnetic bandgap (EBG)‐based textile antenna for wireless body area networks (WBAN) applications, operating at frequency 2.45 GHz. The antenna radiator is composed of 2 × 1 array of EBG cells printed on same side of the substrate with partial ground plane to form a compact EBG surface, excited with a 50 Ω inverted L‐strip feed line. The partial ground plane with EBG cells is used to miniaturize the proposed antenna of size 40 × 20 × 0.3 mm3. The proposed compact asymmetric dual L‐strip fed wearable antenna (DLSWA) with EBG structure is fabricated on denim (jeans) substrate having dielectric constant (ɛr) 1.7 and thickness of 0.3 mm. The design of proposed antenna is optimized for Industrial, Scientific, and Medical (ISM) band (2.4‐2.48 GHz)through various parametric variations with simulated impedance bandwidth (BW) of 12.2% (2.3‐2.6 GHz) for reflection coefficient |S11| ≤ −10 dB and also exhibits stable radiation patterns with simulated peak realized gain of almost 3.5 dBi in the entire operational frequency band. The performance of proposed wearable antenna on human body is also studied and observed low specific absorption rate (SAR) value of 0.6 W/kg over 10 g of human tissues. The proposed compact asymmetric DLSWA is designed, fabricated, and tested. The simulated results of designed antenna are verified and validated with measured results which show good agreement for all radiation characteristics of proposed antenna for WBAN applications.

Dual-band antenna modification by using dual bad EBG structure for WLAN/WiMAX applications

In this paper, a U-slot antenna as represent of dual-band antenna is studied. This antenna covers the WLAN/WiMAX application with a moderate gain of 4.5 dBi. The antenna excites two modes of TM10 and TM20 and consequently with excitation of high order modes surface currents of antenna substrate increase. To overcome this drawback a dual-band electromagnetic bandgap (EBG) is offered and results of EBG unit cell is matched with the U-slot antenna operation bandwidth at two bands. Finally, arrange of unite cell array and antenna for two goals is investigated. As results prove, the combining antenna with EBG cells can solve the mutual coupling effect more than 20 dB and improve gain and bandwidth of antenna for about 3.5 dBi and 1% for each frequency band, respectively.

Metasurface-Enabled Antiparallel Dual-Beam Rectangular-Waveguide Antenna

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.

A Compact Wideband SIW Bandpass Filter with Wide Stopband and High Selectivity

A novel method to design a wideband substrate integrated waveguide (SIW) bandpass filter (BPF) with compact size, wide stopband and high selectivity is presented. In this method some unique electromagnetic band-gap (EBG) cells are periodically etched on the top layer of SIW to realize a wide passband propagating below the equivalent waveguide cutoff frequency. By changing the configuration of EBG cells, undesired harmonics in upper stopband can be suppressed and a wideband BPF with wide stopband can be obtained. By symmetrically loading two complementary split ring resonators (CSRRs) on the tapered gradient lines of the input/output ports, a transmission zero near the passband can be introduced, and it makes the frequency selectivity of upper sideband improve significantly. As a verification, a wideband SIW BPF with a 3.02 GHz absolute bandwidth (ABW) and a 64.7% fractional bandwidth (FBW) centered at 4.67 GHz is designed, simulated, manufactured, and measured. The results of the experiment and simulation are in good agreement.

A modified interdigital EBG reflector for wireless body area network applications

AbstractA modified, compact, and via‐less interdigital electromagnetic band gap cell intended for wearable application at medical body area network (MBAN), and Wi‐Fi bands is reported in this article. The reflection phase of the proposed EBG unit cell is then investigated to design a reflector consisting of 3 × 2 array of EBG cells for an efficient radiation of a planar monopole antenna. The size and shape of the EBG unit cell has been designed in such a way that it achieves 0° reflection phase with minimum dimension of 14.3 and 15.34 mm along x‐axis and y‐axis, respectively. Subsequently, the surface wave rejection ability of the EBG incorporated ground plane is also studied and presented in this article. A planar monopole antenna incorporating the proposed EBG reflector at MBAN frequency exhibits gain, and efficiency of 6.4 dB, and 95%, respectively, and has net dimension of 34 mm × 55 mm × 4.67 mm along x‐axis, y‐axis, and z‐axis, respectively. Finally, specific absorption rate (SAR) analysis carried out for one layer, homogenous model, and three‐layer, heterogeneous model, shows a considerable reduction in SAR values for 0.5 W of power fed to the antenna. The effectiveness of the proposed approach is demonstrated through good agreement between the simulated and the experimental results.

Design of defective electromagnetic band-gap structures for use in dual-band patch antennas

Generally, the surface wave of an antenna can be suppressed by integrating the electromagnetic band-gap (EBG) structures. However, to achieve this effect, the EBG cells must be reasonably designed, otherwise it may lead to performance degradation instead. In this article, a dual-band pinwheel-shaped slot EBG structure is proposed. When applied to a patch antenna, defects are introduced into 3 rows of the EBG unit cells. The proposed antenna, incorporating EBGs designed with structural defects, to radiate at 4.9 and 5.4 GHz is simulated and tested. The measured results show that the −10-dB bandwidth of the proposed EBG antenna is extended by 41% and 25.4% at low frequency and high frequency, respectively. In addition, the peak gain of the proposed EBG antenna is increased by 2.44 dB at 4.9 GHz and 2.86 dB at 5.4 GHz with >40% efficiency. When compared with the periodic EBG antenna, this antenna is more effective. Thus, these experimental results show that the performance of the EBG antenna can be improved by interrupting the periodicity of the EBGs structures.