Electromagnetic Band Gap Elements Research Articles

3-D printed triple-band metasurface filter based on groove gap waveguide technology

This article proposes a 3-D printed high selectivity triple-band metasurface bandpass filter (BPF) for millimeter-wave applications using groove gap waveguide (GGW) technology. Firstly, the metasurface composed of electromagnetic bandgap elements in GGW technology is designed and analyzed. This configuration effectively mitigates radiation and electromagnetic wave leakage. Subsequently, the multimode split-type topology under the resonances of TE102 and TE201 modes is utilized to realize a triple-band bandpass response with a compact circuit size. Additionally, the TE101 mode considered as an extra energy coupling path is used to introduce more transmission zeros (TZs). Finally, the design prototype is fabricated using 3D printing technology. The measured results are in good agreement with the simulated ones, providing an excellent option for mm-wave wireless communication systems.

VHF/UHF Miniaturized Ferrite-EBG Composited Choke Structures

Parasitic currents on the sheaths of the coaxial cables will deteriorate the performance of the antenna, so the choke structures are needed. While a-quarter-wavelength choke sheaths at VHF and UHF are very long, miniaturized ferrite-EBG composited choke structures are proposed. The ferrite refers to ferrite magnetic beads. Electromagnetic bandgap (EBG) element is consisted of multi-section metal tubes with length relatively shorter than a-quarter-wavelength. The integrated structures are formed by arranging EBG elements and beads alternately along the coaxial line. The proposed choke structures combine the wideband choke performance of the ferrite beads and the high efficiency of the EBG structures. Furthermore, due to the difficulty of the quantitative measurement of the choke structures in an open space, a measuring setup designed in a transmission line model is devised. The choking effects of the proposed structures can be characterized by the |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | parameter of the measuring device, as the direction of the currents flowing on the sheaths of feeding cables are the same as that of the currents on the inner conductor of the measuring device. Meanwhile, choking bandwidth, efficiency and size of the ferrite-EBG composited choke structures are compared with that of EBG structures and beads. The influence of different numbers of the proposed structures is studied. A prototype is fabricated and measured. The overall size of the ferrite-EBG composited choke structures is 0.25 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ×0.024 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ×0.024 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> (415 mm ×40 mm ×40 mm) ( λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> is the wavelength of the lower end of the operating frequency band). The measured choking band ( |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | <; -10 dB) is in the region of 181-343 MHz.

A Microcontroller Unit-Based Electromagnetic Bandgap Control Scheme: Application for Enhancing Isolation in an Antenna Array and the EMI Scanner System Speed Thereof

This article presents an adaptive electromagnetic bandgap (EBG) scheme based on a microcontroller unit (MCU) for reducing the mutual coupling in an antenna array designed for electromagnetic interference (EMI) scanner system enhancement (e.g., scanning speed, lower weight and size, and maintenance). For the first time, the EBG is configured via an MCU to enable the finest control of the equivalent lumped elements of the EBG, realizing optimal isolation between/among the antennas at very close distances (1.2 mm $= 0.05\lambda $ at 10 GHz), which typically translates into longer distances between/among the antennas and/or more EBG elements (examples are referenced for comparison). The desired optimal isolation performance is realized by the EBG scheme combined with varactor diodes under the control of the MCU (later the microcontrolled EBG or MC-EBG) referencing a database compiled from the simulation results. In a simulation, the optimal isolation was found to be −58 dB ( $S_{21}$ ) between two small-loop antennas (later the 2-SLA prototype) on a high-permittivity substrate ( $\varepsilon _{r} = 12.8$ , 4-mm thick). For the 4-SLA prototype devised here under identical substrate conditions, the optimal isolation points were found to be −30 dB ( $S_{21}/S_{31})$ and −38 dB ( $S_{41}$ ). During the measurements, when compared under a EBG-standalone tuned isolation at 10 GHz, the measured isolation of the ultimately selected 4-SLA prototype was found to be better by more than 29 dB (−7 to −36 dB) between the closest SLAs ( $S_{21}/S_{31})$ and by more than 35 dB (−18 to −53 dB) between the farthest SLAs ( $S_{41}$ ) at the same frequency. The accordant S-parametric results from both the simulation and the measurement are supported by the simulated $H$ -field distribution (dBmA/m). The $H$ -field from one SLA to the others was found to be reduced by more than 30 dB with the MC-EBG activated (MCU ON), and this is compared with the value of 13 dB from the tuned EBG-standalone case (MCU OFF). The final 4-SLA prototype was deployed in an actual 1 mm over-the-air (OTA) near-field EMI test at 10 GHz. The final field application results prove an enhancement in the EMI scanning speed (few hours versus few minutes) with a very low error rate (clear EMI detection), with the ultimate goal of the MC-EBG thus successfully accomplished.

New electromagnetic band gap antenna for multiple ultra wide band applications

This paper presents a compact multiband microstrip electromagnetic band gap (EBG) patch antenna with partial ground used for the 2nd and 3rd mode excitation, allowing multiple band resonance and control of the resonance frequencies. The electromagnetic band gap elements are inserted to improve obviously output parameters (gain directivity, return loss, maximum radiation Intensity, and radiation efficiency). Simulation and measurement results show a multiband antenna WiMAX, WLAN-band applications that can effectively cover three separated bandwidths (2.12, 3.1 and 5.41 GHz). The proposed compact antenna is grounded on a 1.6 mm-thick FR4 epoxy substrate with overall dimension of 0.305λ × 0.305λ × 0.012λ at lower frequency. The whole size of the proposed antenna with an overall area of 25 × 38 × 1.6 mm3 is maintained, and a low cross-polarization level within the operating frequency range. Electromagnetic Band Gap materials, artificially engineered structures, have the main role to improve the output performance of the patch antennas.

Novel design of triple-bands EBG

This paper presents a novel design for a triple band electromagnetic band gap (EBG) structures that provides three band gaps, with operating frequency of below 10 GHz, while the ordinary mushroom like EBG structure gives only one band gap. Complexity reduction (reduce the number of unit cells and Vias) was achieved by replacing each four cells of the Mushroom like EBG by the one of double slotted type EBG (DSTEBG) or triple side slotted EBG (TSSEBG). The Mushroom like EBG was further modified by increasing its size and inserting the slots to gain more capacitance and inductance which resulted into triple band stop.The new designs wer compared with bandwidths expressed by other EBGs and -20 dB cut-off frequencies. The size of EBG element and the gap between EBG elements, and slot width were investigated to analyse their effect on the transmission response. The structures were designed from 2.54 mm Rogers RT/Duroid 6010 substrate with relative permittivity of 10.2 and loss tangent of 0.0023. Among the investigated EBGs, the single band mushroom like EBG and the triple band of the TSSEBG demonstrated better bandwidth and lower resonance frequency performance, whereas the DSTEBG showed larger bandwidth for the first and third band. The proposed EBGs could be useful in the antenna design and other microwave circuits.

Wearable Circular Ring Slot Antenna With EBG Structure for Wireless Body Area Network

A wearable circular ring slot antenna with electromagnetic bandgap (EBG) structure for wireless body area network application is proposed in this letter. According to the analysis of equivalent circuit model, the volume of the EBG element is miniaturized for wearable applications. The measured impedance bandwidth of the proposed antenna is observed to be 2.28–2.64 GHz, which covers the 2.4 GHz Industrial Scientific Medical (ISM) band. The measured half-power beamwidths are 60° and 54° in the H -plane and the E -plane, respectively, and the front-to-back ratios are 17 and 13 dB in the H -plane and the E -plane, respectively. The specific absorption rate calculated values for tissue in 1 g (for the U.S. standard) and 10 g (for Europe standard) are both less than the limitations. In conclusion, it is proper to use the proposed antenna in wearable applications.

Gain Enhancement and RCS Reduction for Patch Antenna by Using Polarization-Dependent EBG Surface

A novel antenna design is proposed to enhance the gain and reduce the radar cross section (RCS) of a patch antenna by using metamaterial surface. A polarization-dependent metamaterial surface composed of blocks of slotted electromagnetic bandgap (EBG) structures are adopted in this letter. The layout pattern of the slotted EBG elements is designed to enhance the gain of the antenna. Chessboard configuration is further equipped for scattering cancellation. The induced currents on the EBG are studied, resulting in the mechanism of the gain enhancement by the EBGs clearly explained for the first time. This enables the strategy of designing a high-gain and low-RCS antenna by using EBGs. Full-wave simulations validate that high gain in the operating frequency band and low-RCS in a broad frequency band for normal incidence are achieved by the proposed antenna.

Reflectarray with EBG elements for improved radiation characteristics

A reflectarray composed of elements with electromagnetic bandgap (EBG) characteristics to improve radiation performances is proposed. The EBG elements are composed of patches and multiple via-holes to provide required reflection phase and bandgap characteristics at target frequency of 10 GHz. Compared with a normal patch reflectarray without EBG elements, the gain is improved by 1.4 dB, and the SLLs are suppressed by 1.5 dB (E-plane) and 5.3 dB (H-plane), respectively.

EXPERIMENTAL STUDY OF THE BEHAVIOR OF AN EBG-BASED PATCH ANTENNA SUBJECTED TO MECHANICAL DEFORMATIONS

This work deals with the behavior of a patch antenna equipped with squared electromagnetic bandgap (EBG) structures and subjected to various mechanical deformations (twisting and bending deformations). The EBG structures have a stop band frequency (rejection) feature, allowing the coupling and the undesired electromagnetic interferences to be reduced. The in∞uences of the deformations on the mutual coupling and radiation patterns of an antenna equipped of those EBG elements are experimentally studied.

Planar rat-race coupler with microstrip electromagnetic bandgap element

This article presents the design of microstrip electromagnetic bandgap element and its applications in the planar rat-race hybrid coupler with the purpose of harmonic suppression and size reduction.The measured results of proposed hybrid coupler with 1.25 GHz central frequency verify its attractive performance with an insertion loss of less than 3.4 dB, a return loss of about 20 dB, an isolation of 32 dB, 17 dB suppression for the second harmonic, 25 dB suppression for the third harmonic, and 22 dB suppression for the fourth harmonic. In particular, with no loss of the performance, the area of proposed rat-race coupler, achieving 57% save in size, has been successfully reduced from 38.82 cm2 (the area of conventional hybrid coupler) to 16.72 cm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2619–2622, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26308

Planar Electromagnetic Bandgap Structures Based on Polar Curves and Mapping Functions

A type of electromagnetic bandgap structure is described that is easily parameterized and can produce a range of square and spiral geometries. Individual electromagnetic bandgap (EBG) geometries are defined on a cell-by-cell basis in terms of their convolution factor k, which defines the extent to which the elements are interleaved and controls the coupling slot length between adjacent elements. Polar equations are used to define the slot locus which also incorporate a transformation which ensures the slot extends into the corners of the square unit cell and hence extends the maximum slot length achievable. The electromagnetic properties of the so-called polar EBG are evaluated by means of numerical simulation and measurements and dispersion diagrams are presented. Finally, the performance is compared with other similar miniaturized EBG cell geometries. It is shown that the polar EBG has better angular stability than the equivalent square patch design and is comparable in terms of performance to other low frequency EBG elements. At the same time it retains the ability to fine tune the response by adjusting k.

Microstrip Patch Antennas on Tunable Electromagnetic Band-Gap Substrates

A tunable metamaterial in integrated circuit structures is investigated through an example of a microstrip patch antenna on a mushroom-type electromagnetic band-gap (EBG) structure. The patch antenna is designed as a half-wavelength resonator of an EBG loaded microstrip transmission line. The operating frequency of a patch antenna can be switched and controlled dynamically by loading diode switches in between vias and the ground plane. When the switches are on, the EBG surface is short to the ground and is at its on-state; while when the switches are turned off, the EBG surface is dc open and is at its off-state. It is found that the resulting patch antenna in-band resonant frequencies are very different at these two states. Antenna dual-band frequencies, gain, efficiency, and radiation patterns are characterized. The designed switchable EBG-patch antenna is fabricated and tested in these two states. The measurement is found in good agreement with simulation. An example is also given for the case of selected switches within the EBG elements to tune dynamically the resonant frequency.

RF RAT-RACE COUPLERS WITH U-TYPE DGS MICROSTRIP ELECTROMAGNETIC BAND GAP ELEMENT

In this letter, an investigation of a novel compact rat-race hybrid coupler incorporating a U-type defected ground structure (UDGS) is presented. Served by this microstrip electromagnetic band gap element (MEBE) technology, the size of the coupler is reduced due to its slow-wave effect and its band-stop effect enables strong high-order harmonics rejection. In the meantime, the measured performance of the proposed coupler is comparable to that of a conventional microstrip hybrid coupler. This miniaturization and harmonic suppression technology has great potential application in MICs and MMICs to reduce circuit size, lower material cost and improve the overall performance of wireless communication systems.

Miniaturized and harmonics‐rejected slow‐wave branch‐line coupler based on microstrip electromagnetic bandgap element

AbstractThis article presents a planar branch‐line hybrid coupler with an effective technique for harmonic suppression and size reduction. The proposed technique served by a microstrip electromagnetic bandgap element entitled MEBE (compact microstrip resonant cell) is used to suppress the harmonics and reduce the length of a quarter wavelength line when compared with the conventional branch‐line coupler. The planar structure enables an easy circuit implementation in printed circuit boards without any additional process and lumped elements. From the measured results, better than 30 dB suppression for the second harmonic and 18 dB suppression for the third harmonic are obtained while maintaining the characteristics of conventional branch‐line hybrid coupler. It is able to achieve two insertion losses of less than 3.5 dB, the return loss of 18 dB, and isolation of 19 dB at operating frequency. With our improved beeline compact microstrip resonant cell, compact branch‐line coupler occupying areas of 35.86% relative to conventional designs has been realized. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1080–1084, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24241

MICROSTRIP ELECTROMAGNETIC BANDGAP ELEMENT ON GROUND FOR HYBRID RING COUPLERS

In this paper, a novel compact rat-race hybrid coupler incorporating square open-loop defected ground structures (SOL-DGSs) is designed and verified. As a new wave of microstrip electromagnetic bandgap element (MEBE) technology on ground plane, the bandgap characteristic of SOL-DGS is employed to reject the high-order harmonics without any additional filter and the excellent slow-wave effect of SOL-DGS is studied and utilized to reduce the circuit size in the design of the hybrid coupler. The measured insertion losses are 3.54 dB and 3.63 dB for two input ports. The isolation between port 1 and port 3 achieves around -30 dB. Furthermore, the proposed rat-race coupler successfully rejects the second, third, fourth and even fifth harmonic signals.

Power divider with microstrip electromagnetic bandgap element for miniaturisation and harmonic rejection

A novel technique for harmonic suppression and size reduction in planar Wilkinson power divider is presented. The proposed technique served by a microstrip electromagnetic bandgap element (MEBE) is used to reject the unwanted harmonics by employing its stopband effect and to reduce the length of microstrip by utilising its slow-wave effect. The whole size of the proposed divider has been reduced by 39% compared to the conventional power divider. Higher harmonics are effectively suppressed.

Reduction of Mutual Coupling in a Microstrip Patch Array Fed by a Triplate Waveguide with EBG Elements

This letter presents mutual coupling reduction in an E-plane arranged microstrip patch array fed by a triplate waveguide. Five mushroom-like electromagnetic band-gap (EBG) elements arranged in one column are embedded both between two radiating patches and between the feeding lines for suppression of the surface wave and the parallel plate mode, respectively. Validity of the proposed EBG elements is confirmed by the measurement.

Wideband reduced size electromagnetic bandgap structure

A novel electromagnetic bandgap element geometry is presented with compact dimensions and a wide bandwidth. The element has a small cell size of 22.8 mm and a measured bandwidth of 24% at 1.6 GHz. A useful second bandgap can be realised with a bandwidth of 6% at 2.5 GHz. Simulations show that using the same element dimensions on a higher dielectric constant substrate provides a bandgap at the lower 900 MHz GSM band with sufficient bandwidth.