Electromagnetic Bandgap Substrate Research Articles

Passive UHF RFID Packaging With Electromagnetic Band Gap (EBG) Material for Metallic Objects Tracking

Passive ultrahigh frequency (UHF) radio frequency identification (RFID) is a promising technology for products tracking in logistics or routing packages in supply chain. However, passive UHF RFID tag's performance degrades a lot when it is placed near metal plane or water surface. Many designs like microstrip antenna and ferrite material antenna have been used to solve this metal-water problem. But their usage is limited by narrow bandwidth and low antenna gain. The electromagnetic band gap (EBG) material which exhibits a unique forbidden band gap at certain frequency offers a potential solution to solve this metal-water problem. In this paper, we disclosed a new method using EBG material to insulate the UHF RFID tag from backside objects, so that the tag could still work on metallic surface. The design of EBG material for UHF RFID which operates at 915 MHz under federal communications commission regulation was discussed in this paper. The simulation results showed that the EBG RFID tag can be read on metal. The measurement results indicated that the read range of RFID tag with EBG substrate is up to 9 m on metal surface.

Enhanced Gain and Bandwidth of Patch Antenna Using EBG Substrates

Microstrip patch antenna becomes very popular day by day because of its ease of analysis and fabrication, low cost, light weight, easy to feed and their attractive radiation characteristics. Although patch antenna has numerous advantages, it has also some drawbacks such as restricted bandwidth, low gain and a potential decrease in radiation pattern. In recent years, attention to use Electromagnetic Band Gap (EBG) substrates to overcome the limitations of patch antenna. In this paper, we propose a rectangular microstrip patch antenna with EBG substrates and compare the performance of the proposed antenna with a conventional patch antenna in the same physical dimension. Due to the presence of the EBG structure in the dielectric substrates, the electromagnetic band gap is created that reduces the surface waves considerably. As a result, the performance of the proposed antenna is better comparing the conventional existing microstrip patch antenna.

Dipole Antenna Above EBG Substrate for Local SAR Reduction

This letter investigates the performance of a dipole antenna above an electromagnetic band-gap (EBG) substrate to realize a low specific absorption rate (SAR) antenna. The frequency band considered is 3.5 GHz, which is assigned to fourth-generation mobile communications. One of the motivations for this proposal is that the size of the EBG substrate can be small enough for a handset. The dipole antenna above the EBG substrate was found to reduce the local SAR in a cubic head model by 84% as compared to the local SAR of a perfect electric conductor. The radiation efficiency was also improved by 10%. These results were also confirmed for a realistic head model.

A New Approach for the FDTD Modeling of Antennas Over Periodic Structures

A new approach is proposed for the time-domain modeling of antennas over periodic substrates. This class of problems would typically require a time-consuming simulation of the antenna structure with a finite number of unit cells of the periodic substrate, chosen to be large enough to achieve convergence. On the contrary, the present work employs periodic boundary conditions applied at the substrate, to dramatically reduce the computational domain and hence, the cost of such simulations. Emphasis is given on radiation pattern calculation, and the consequences of the truncated computational domain of the proposed method on the computation of the electric and magnetic surface currents invoked in the near-to-far field transformation. The theoretical aspects of the proposed methodology are complemented by numerical examples of a wire and an integrated patch antenna over electromagnetic band-gap substrates.

Efficient Excitation of an EBG Guide Designed Using a Defect Triangular Lattice of Holes

A triangular lattice of holes is used to design an electromagnetic band-gap (EBG) waveguide for TM modes (magnetic field parallel to the substrate surface and perpendicular to the holes) for operation in the millimeter-wave range. This EBG waveguide can be used in planar circuits, and it is not as bulky as traditional waveguides. A microstrip line was used for the excitation of the waveguide. The dispersion diagram of the triangular lattice is calculated and used in the design of an EBG substrate that operates around 30 GHz. Simulation of the EBG waveguide of 64.05 mm length (equivalent to 21 EBG cells) demonstrated an insertion loss better than 2.5 dB from 28 to 31.5 GHz and return loss below -10 dB across the same band. Despite the lack of complete TM band-gap for such a waveguide, it is demonstrated that signal confinement within the defect region can be obtained by appropriate excitation of the structure. The structure was fabricated and measured, and good agreement between the measured and simulated data was noticed. The observed constant group delay of this waveguide across its operating band implies low frequency dispersion of the structure. Also, the dispersion diagram of the fundamental guided mode is linear, which is an indication of its quasi-TEM nature.

Gain enhancement of a microstrip patch antenna using a circularly periodic EBG structure and air layer

Abstract This paper describes the gain improvement of a circular microstrip patch antenna achieved using an electromagnetic bandgap (EBG) structure and an air layer. The microstrip patch antenna was fed by a coaxial probe and integrated in an EBG substrate that included an air layer. The gain of this antenna was 6.5 dB greater than that of a conventional circular patch antenna. The actual measured radiation patterns and gains of the proposed antenna agreed closely with simulated results.

Dual-Band Wearable Textile Antenna on an EBG Substrate

Performance of a dual-band coplanar patch antenna integrated with an electromagnetic band gap substrate is described. The antenna structure is made from common clothing fabrics and operates at the 2.45 and 5 GHz wireless bands. The design of the coplanar antenna, band gap substrate, and their integration is presented. The band gap array consists of just 3 times 3 elements but reduces radiation into the body by over 10 dB and improves the antenna gain by 3 dB. The performance of the antenna under bending conditions and when placed on the human body are presented.

Hybrid Dielectric Resonator Antenna With Circular Mushroom-Like Structure for Gain Improvement

In this paper, the performance of a cylindrical dielectric resonator antenna (DRA) is improved using a new cylindrical electromagnetic bandgap substrate. The DRA is fed by a coaxial probe and integrated within a cylindrical electromagnetic bandgap (EBG) substrate to increase the antenna gain. The cylindrical electromagnetic bandgap structure is composed of two distinctive periodic structures. The first structure is made of metallic rings, while the second is formed of grounding vias, which are placed radially and circularly. To describe and optimize this EBG stucture, a parametric study using a finite integration method was carried out. Furthermore, an antenna prototype was fabricated and measured to validate the proposed concept. The radiation patterns and return loss obtained from measurements demonstrate a good performance in terms of impedance matching and gain enhancement.

Metamaterial Superstrate and Electromagnetic Band-Gap Substrate for High Directive Antenna

A high directive planar antenna made from a metamaterial superstrate and an electromagnetic band-gap (EBG) substrate has been investigated. A patch antenna surrounded with EBG structures is used as the radiation source. The CST Microwave Studio is used for the simulation. The results show that the gain of the antenna with metamaterial is 21.6 dB at the operating frequency of 14.6 GHz. Compared with the patch feed with the same aperture size but without the metamaterial superstrate, the performance of the antenna is improved obviously and the gain increases about 12.4 dB.

Low Profile GALILEO Antenna Using EBG Technology

A dedicated low profile antenna for geodesic applications is presented. This type of antenna requires mitigation of multipath signals to achieve sub-centimeter level of precision. Typically, bulky and heavy choke ring structures have been used to reduce the effects of multipath interference. The antenna presented here consists of a low temperature co-fired ceramic (LTCC) patch antenna immersed in an electromagnetic bandgap (EBG) substrate. The EBG substrate reduces the effects of multipath by blocking the propagation of surface waves. The result is an antenna showing good multipath rejection and a stable phase center. The advantage of printed EBG substrates is that they can be realized in a low-weight, low-price, and low-profile fashion. First prototypes have been manufactured and tested, and its performance has been compared to that of a more classical choke ring antenna.

Gain Enhancement of a Microstrip Patch Antenna Using a Cylindrical Electromagnetic Crystal Substrate

The performance of a circular microstrip patch antenna is improved using a new cylindrical electromagnetic bandgap (EBG) substrate. The microstrip patch antenna is fed by a coaxial probe and is integrated within a cylindrical electromagnetic bandgap substrate, based on the mushroom-like substrate, to increase the antenna gain. The cylindrical electromagnetic bandgap structure is a combination of two periodic structures with different periods. One is made of metallic rings and the other of grounding vias, which are disposed such as to form a radially and circularly periodic structure. A parametric analysis using a full-wave method was carried out in order to design the EBG structure. With the proposed concept, an antenna prototype was fabricated and tested. The radiation patterns and return loss obtained from measurements show a good impedance matching and a gain enhancement of the proposed antenna.

Dual‐band operation of an electromagnetic band‐gap patch antenna

AbstractIn this article, a novel concept of electromagnetic band‐gap (EBG) antenna is proposed: dual/multiple band antenna resonances can be achieved using a single patch radiator based on layered EBG substrates. The generalized design procedure is presented. Experimental results demonstrate good agreement with the theoretical prediction and numerical results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2454–2458, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22728

Radiation Characteristics of a Microstrip Patch Over an Electromagnetic Bandgap Surface

Radiation characteristics of a microstrip patch over an electromagnetic bandgap (EBG) substrate are investigated in this paper. This paper focuses on a mushroom-type EBG structure, although the design is applicable to various EBG profiles. The patch antenna is modeled as a half-wavelength resonator of an EBG-loaded microstrip transmission line. Through a full-wave eigenmode analysis of a microstrip line on an EBG structure, it is found that the resonant patch will not see a high-impedance surface (HIS), but rather it is coupled to the EBG structure as an open cavity resonator. Due to strong near-field coupling, the propagation characteristics including the bandgap zones are very different with or without the patch cover. The use of an EBG structure as a bulk material for antennas is seen inappropriate. The EBG surface is found to have the effect of reducing the patch resonant length and bandwidth. A prototype of a microstrip line proximity fed to a patch antenna is fabricated and tested to verify the analysis.

Design and Characterization of the EBG Waveguide-Based Interconnects

An alternative signal guiding structure, which can be integrated within the printed circuit substrates, is investigated in this paper. The structure is realized by forming a rectangular waveguide in a 2-D electromagnetic bandgap (EBG) substrate. In this manner, a bandpass interconnect is provided that proves to be a promising technology for the high-speed/high-frequency system design. A systematic approach to the design and optimization of this interconnect is presented here followed by investigation of various bend geometries. The studied structures exhibit very low levels of loss and leakage when inspected at tens of gigahertz frequency range. Moreover, the near-end and the far-end crosstalks are monitored in multiple interconnects proving the high efficiency of this alternative routing structure in dense layouts. Nonetheless, the crosstalk performance is degraded as the coplanar microstrip-to-waveguide transitions are added. These transitions are essentially tapered microstrip lines that are connected to other circuitries. Continuous via fences are inserted in the transition sections of multiple structures demonstrating significant improvement in the crosstalk performance.

Broadband Archimedean spiral antenna above a loaded electromagnetic band gap substrate

The development of a low profile, lightweight, broadband spiral antenna for airborne applications is described. The use of an electromagnetic band gap substrate with loads as reflector for an Archimedean spiral antenna is proposed. A method based on a transmission line model is presented to design this loaded electromagnetic band gap substrate. Simulation and measurements results demonstrate the applicability of the concept. A good impedance matching as well as a good circular polarisation are achieved over a 10:1 frequency bandwidth. Finally, thickness and weight of this new antenna are greatly reduced and their performances are better compared with a conventional spiral antenna with unidirectional beam.

Dual-band wearable antennas over EBG substrate

A dual-band coplanar patch antenna integrated with an electromagnetic bandgap substrate is reported. The antenna structure is made from common clothing fabrics and operates at the 2.45 and 5.1–5.8 GHz wireless bands. The bandgap array consists of just 3×3 elements but reduces radiation into the body by over 10 dB and improves the antenna gain by 3 dB.

Multiband planar antennas on electromagnetic bandgap substrates: Complex global optimization of the structure

AbstractThe paper presents a complex global optimization of a four‐band planar antenna on an electromagnetic bandgap substrate. As a typical representative of such antennas, a triple U‐slot patch antenna is chosen. The full‐wave model of the antenna is developed in CST Microwave Studio. Simulation results are exported to macros in Visual Basic, and the structure is optimized by the particle swarm algorithm, which simultaneously changes parameters of the substrate and the layout. As an optimization criterion, impedance matching in the GSM bands and the Bluetooth one is considered. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:2532–2534, 2006; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.22006

Improving microstrip patch antenna performance using EBG substrates

Microstrip patch antennas mounted over a high impedance electromagnetic bandgap (EBG) substrate are studied. The structure is equivalent to a new microstrip antenna, where the conducting ground plane is replaced by a high impedance EBG layer. Initially, the bandgap of the EBG structure is determined. Then, patch antennas with this EBG ground plane are designed to work within and outside the bandgaps. Parametric studies are conducted to maximise their impedance bandwidths and gains. It is found that very wide bandwidths, of around 25%, can be obtained by variation of the original antenna and EBG parameters. Their gains are similarly increased. Sample antennas are also fabricated and tested, to verify the designs.

An X-Band Microstrip Phase Shifter Using an Electromagnetic Bandgap Backplane

A new microstrip compatible phase shifter circuit is introduced. The phase shifter uses a strip-type electromagnetic bandgap (EBG) substrate in place of the solid metal ground plane. Such EBG substrates, when made of ferroelectric materials, can produce variable phase constants useful for phase shifter applications. Test models using two different EBG substrates with dielectric constants of 9.2 and 10.2 showed 44.5 degrees of phase difference with 1.7 dB of added insertion loss at 10 GHz from a line originally 504 degrees long.

An electromagnetic bandgap curl antenna for phased array applications

A promising way to reduce the problems created by surface waves in printed phased array antennas is to use an electromagnetic bandgap (EBG) substrate instead of a standard dielectric. Two metallo-dielectric EBG substrates well suited for phased array applications have been designed and tested. One of them has a compact unit cell and exhibits a broad bandwidth performance. The other EBG structure has a narrower bandwidth but is simple to manufacture and has a low mechanical profile. Single radiating elements and a small linear array have been manufactured on a standard dielectric substrate and on the EBG substrates. The measurements show a significant improvement in radiation efficiency as well as of the front to back ratio for the antennas manufactured on the EBG substrates compared to the ones obtained for the antennas manufactured on the standard dielectric substrate. These results clearly demonstrate the effectiveness of the EBG substrates in reducing the surface and guided waves.