EBG Resonator Antenna Research Articles

Wideband High-Gain EBG Resonator Antennas With Small Footprints and All-Dielectric Superstructures

A novel method is presented to design single-feed high-gain EBG resonator antennas (ERAs) with significantly wider bandwidths. Dielectric contrast is introduced to 1-D EBG superstructures composed of unprinted dielectric slabs, and the thicknesses of each of these slabs is optimized to achieve a wideband defect mode in a unit-cell model. Next, antennas are designed and their superstructure areas are truncated to increase the antenna bandwidth and aperture efficiency while decreasing antenna footprint. We demonstrate that a small superstructure area increases the 3-dB bandwidth of ERAs significantly. A prototype ERA designed with a single feed and superstructure area as small as ${\hbox {1.5}} \lambda_0 \times {\hbox {1.5}} \lambda_0$ has a measured 3-dB directivity bandwidth of 22% at a peak gain of 18.2 dBi. This prototype antenna was made out of three slabs of different dielectric constants, two of them touching each other. This prototype demonstrates more than 85% reduction in the ERA footprint alongside a drastic improvement in bandwidth over the 3%–4% measured bandwidth of the classical single-feed ERAs with unprinted slabs.

Radiation-Enhancement Properties of an X-Band Woodpile EBG and Its Application to a Planar Antenna

A woodpile Electromagnetic Bandgap (EBG) material has been designed, by using an in-house code that implements the Fourier Modal Method (FMM). A couple of alumina-woodpile samples have been fabricated. Several results have been collected for the transmission behaviour of the woodpile and of resonators with woodpile mirrors, in a shielded anechoic chamber, by using a vector network analyzer, in the 8–12 GHz range. These new experimental data highlight interesting properties of 3D EBG resonators and suggest possible innovative applications. Comparisons of the collected results with FMM show a satisfactory agreement. An application of the EBG resonator has been considered, for gain enhancement of a microstrip antenna: an increase of about 10 dB in the broadside gain has been measured; experimental data and numerical results obtained with the commercial software HFSS show a good agreement. A comparison is presented between EBG resonator antennas and two-dimensional uniform arrays. Finally, HFSS results are provided for EBG resonator antennas working at higher frequencies or with a more selective superstrate: a gain enhancement of more than 18 dB is achieved by such antennas.

THICK METAL EBG CELLS WITH NARROW GAPS AND APPLICATION TO THE DESIGN OF MINIATURIZED ANTENNAS

The paper presents a methodology to achieve e-cient low-proflle electromagnetic bandgap (EBG) antennas based on thick EBG unit cells. The EBG cells are composed of thick metal patches separated by narrow high aspect ratio (HAR) gaps, and positioned on a PEC-backed substrate. This approach yields new miniaturized EBG cells with considerably reduced electrical size. The miniaturized cells are employed to demonstrate new compact self-excited EBG resonator antennas with considerably reduced operating frequencies. Full-wave simulations and experimental results demonstrate the design approach.

A Circuit Model for the Design of Self-Excited EBG Resonator Antennas With Miniaturized Unit Cells

A circuit model based on Bloch theory is introduced to simplify analysis and design of antennas composed of thick metal electromagnetic band-gap (EBG) cells with large intercell coupling capacitance. The cells are composed of thick metal patches periodically deployed on a metal-backed dielectric slab. Two versions of cells are presented that provide large intercell capacitance, one with narrow high aspect ratio (HAR) gaps between cells and the other with interdigitated gaps between cells. This large capacitance reduces the antenna resonance and dramatically miniaturizes the EBG cells. Three cascaded unit cells are used to demonstrate the applicability of the circuit model to characterize the recently introduced self-excited EBG resonator antenna. Full-wave numerical analysis and experimentation validate the robustness and accuracy of the model over large variations in electrical/physical cell dimensions.

NEW DIELECTRIC 1-D EBG STRUCTURE FOR THE DESIGN OF WIDEBAND RESONATOR ANTENNAS

In this paper, we propose a method to use 1-D dielectric slabs, instead of metallic Frequency Selective Surfaces (FSSs), to produce Partially Re∞ective Surfaces (PRSs) with positive re∞ection phase gradients. The structure is realized by a single kind of dielectric substrate. It is modeled as cascaded transmission lines and then analyzed by virtue of the Smith Chart from the perspective of impedance transformation. A PRS designed by this approach is then applied to the realization of a wideband EBG resonator antenna operating at Ku band which is fed by a slot-coupled patch antenna. The calculated results indicate that the antenna possesses a relative 3dB gain bandwidth of 22%, from 14.1GHz to 17.6GHz, with a peak gain of 17dBi. The impedance bandwidth for the re∞ection coe-cient (S11) less than i10dB, is from 14GHz to 17.7GHz, well covering the 3dB gain bandwidth. A prototype has been fabricated and measured, and the experimental results well validate the simulation. The design method developed here is signiflcantly efiective, and can be easily adopted for antenna designs at other frequencies.

A Simple Dual-Band Electromagnetic Band Gap Resonator Antenna Based on Inverted Reflection Phase Gradient

A simple method is presented to obtain a high-gain dual-band electromagnetic band gap (EBG) resonator antenna. The antenna is based on a one-dimensional EBG structure, made out of two low-cost unprinted dielectric slabs. The EBG structure is implemented as the antenna superstrate, which has been designed to provide a locally-inverted, positive reflection phase gradient with high reflectivity, in two pre-determined frequency bands. A composite dual-band antenna has been designed and tested with a stacked patch feed. Experimental results confirm the dual-band performance of the prototype antenna. Measured peak gains of 14.5 dBi and 15.1 dBi, and 3-dB gain bandwidth of 4.5% and 4.6%, are achieved at 10.6 GHz and 13.2 GHz, respectively. Measured 10-dB return-loss bandwidths are 6.4% and 3.9% in lower and upper bands, respectively. Potential enhancements of antenna radiation characteristics are studied using small 2 × 2 patch array feeds. It was found that such feeds can lead to lower side lobes, higher peak gains and larger gain bandwidths.

The Use of Simple Thin Partially Reflective Surfaces With Positive Reflection Phase Gradients to Design Wideband, Low-Profile EBG Resonator Antennas

Partially reflecting surfaces (PRS) with positive reflection phase gradients are investigated for the design of wideband, low-profile electromagnetic band gap (EBG) resonator antennas. Thin single-dielectric-slab PRSs with printed patterns on both sides are proposed to minimize the PRS thickness and to simplify fabrication. Three such surfaces, each with printed dipoles on both sides, have been designed to obtain different positive reflection phase gradients and reflection magnitude levels in the operating frequency bands. These surfaces, and the EBG resonator antennas formed from them, are analyzed theoretically and experimentally to highlight the design compromises involved and to reveal the relationships between the antenna peak gain, gain bandwidth, the reflection profile (i.e., positive phase gradient and magnitude) of the surface and the relative dimensions of dipoles. A small feed antenna, designed to operate in the cavity field environment, provides good impedance matching (|S11| <; -10 dB) across the operating frequency bands of all three EBG resonator antennas. Experimental results confirm the wideband performance of a simple, low-profile EBG resonator antenna. Its PRS thickness is only 1.6 mm, effective bandwidth is 12.6%, measured peak gain is 16.2 dBi at 11.5 GHz and 3 dB gain bandwidth is 15.7%.

Radiation Properties of EBG Textured Tall Transmission Lines and Applications: A Low-Profile Self-Excited EBG Resonator Antenna

Radiation characteristics of an open-circuit electromagnetic band-gap (EBG) transmission line are employed to demonstrate a new low-profile antenna with high radiation efficiency. The self-excited EBG resonator antenna (SE-EBG-RA) presented is excited using a simple microstrip line, without requiring a separate probe. Tall metal traces enhance radiation while providing less loss, which results in better efficiency. Some desirable properties of the antenna including radiation pattern, gain/efficiency, overall footprint, and the input matching are investigated and discussed.

Experimental demonstration of a dual-band electromagnetic band-gap resonator antenna made out of a simple, single-layer frequency selective surface

The new concept for realizing a dual-band electromagnetic band-gap (EBG) resonator antenna using a simple, single-sided frequency selective surface (FSS) is demonstrated experimentally.The reversal of the gradient of the FSS reflection coefficient phase response, around a FSS resonance frequency, is exploited to achieve two cavity resonance bands in which the FSS behaves as a partially reflective surface (PRS) with an appropriate reflection phase. An FSS, with rectangular slots printed on one surface, is considered for demonstration. The measured performance of a prototype antenna in two bands, around 11.4 GHz and 13.4 GHz, is presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26112

Wide Bandwidth, High-Gain, and Low-Profile EBG Prototype for High Power Applications

In this letter, we present a wide-bandwidth, low-profile, and high-gain electromagnetic band-gap (EBG) resonator antenna that is used for high power and electronic warfare applications. It presents a bandwidth of 71% (from 1 to 2.1 GHz) and a maximum gain of 17 dB. The profile of this antenna is very low (22 mm, which is equivalent to λ/11 at 1.2 GHz). A prototype of this modeled antenna is manufactured, and the measured performances are similar to the simulated ones.

Dual band electromagnetic band gap resonator antenna to feed a reflector antenna

AbstractThis article describes a dual band electromagnetic band gap antenna that is suitable to feed a reflector antenna for space applications. The main objectives consist in the same phase center and the same radiations patterns for the two fréquency bands. The principle, the design, and the performances are given in this article. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1750–1756, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25294

A METHOD TO DESIGN DUAL-BAND, HIGH-DIRECTIVITY EBG RESONATOR ANTENNAS USING SINGLE-RESONANT, SINGLE-LAYER PARTIALLY REFLECTIVE SURFACES

A new method is presented to design dual-band, high- directivity, EBG-resonator antennas using simple, single-resonant, single-layer partially re∞ective surfaces (PRS). The large, positive gradient of the re∞ection phase versus frequency curve of partially re∞ecting surfaces, observed only close to the resonance frequency of the PRS, is exploited for this purpose. An example single-resonant PRS, based on a frequency-selective surface (FSS) composed of a printed slot array, was designed. Then it is used to design an EBG- resonator antenna to demonstrate the feasibility of achieving dual-band performance. Cavity models are employed, together with the re∞ection characteristics of the PRS, to understand the operation of the device at critical frequencies such as cavity resonance frequencies and the PRS resonance frequency. Antenna simulations and computed results conflrm the dual-band operation of this very simple, single-layer, low- proflle EBG-resonator antenna. It resonates in two bands centered at 10.5GHz and 12.3GHz. The peak directivity in each band is 18.2dBi and 20.5dBi, and the 3dB directivity bandwidth of each band is 7.5% and 8.7%, respectively.

Small EBG resonator high-gain antenna using in-phase highly-reflecting surface

A small EBG resonator antenna (1.62λ0×1.62λ0×λ0/4 in size) with specially-located PEC sidewalls to close the resonant cavity is proposed to achieve maximum directivity. An in-phase highly-reflecting surface is installed a quarter-wavelength above the PEC ground plane. For this small EBG resonator antenna, 13.5 dBi measured directivity and 11 dBi peak gain are obtained at 11.6 GHz.

Novel Design of a High-gain and Wideband Fabry-Pérot Cavity Antenna Using a Tapered AMC Substrate

A high-gain and wideband electromagnetic bandgap (EBG) resonator antenna with a tapered artificial magnetic conductor (AMC) ground plane is presented. The proposed EBG resonator antenna is comprised of a frequency selective surface (FSS) superstrate with a strip dipole array and an AMC ground plane with tapered rectangular patches. The realized gain and the bandwidth of the antenna can be improved simultaneously by using the tapered AMC where the phase difference of the reflected waves from the patches with different length is within 180° and the destructive interference among them can be considerably reduced. The maximum gain is increased about 2∼3 dB and the bandwidth is improved about 2.5 times compared to when the uniform AMC is used.

A resonant cavity antenna based on an optimized thin superstrate

AbstractA high‐gain, low‐profile electromagnetic band‐gap (EBG) resonator antenna based on a thin frequency‐selective‐surface (FSS) superstrate is presented. The superstrate thickness has been reduced from 0.25λg in the previous design to about 0.06λg without significantly affecting the antenna performance. The FSS superstrate is made out of standard low‐cost FR4 material. The high‐gain performance is achieved by optimizing the metallic patterns printed on the two surfaces of the superstrate so that a high‐Q resonant cavity is obtained. A prototype demonstrates that an EBG resonator antenna made out of a 0.8 mm thick optimized superstrate can provide a gain as high as over 21 dB at the operating frequency of 12 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3057–3059, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23898

Bandwidth Improvement of EBG Resonator Antennas Using Double-Layer FSS

A double-layer frequency selective surface (FSS) is proposed as a means to enhance the bandwidth of an electromagnetic band gap (EBG) resonator antenna. Due to its inverted reflection phase variation and its wide selectivity bandwidth, the structure used in the radiating wall of the resonator allows increasing the radiating bandwidth of the last one. The resonator is fed by a patch feeding source placed inside the cavity at the proximity of its metallic ground. The antenna bandwidth is significantly improved by virtue of employing the double-layer FSS. Modelled results of an antenna working at 5 GHz are shown.

Enhanced EBG Resonator Antenna as Feed of a Reflector Antenna in the Ka Band

Recent studies have shown that a multibeam reflector antenna could be illuminated by a multifeed electromagnetic bandgap (EBG) structure, in order to achieve a high gain multispot coverage with the simple feed by beam concept and only one aperture. This letter deals with the design of a metallic EBG antenna in the Ka band, feeding a side-fed offset cassegrain antenna (SFOCA) for a European multispot coverage. This reflector presents a high focal-length-to-diameter ratio limiting the defocusing effects for multibeam applications. It, therefore, requires focal feeds with a high directivity and a good radiation pattern quality. The well-known drawbacks of an EBG antenna are the narrow radiation bandwidth for high directivities and also the high sidelobes level reducing the reflector antenna efficiency. Consequently, the work presented in this letter consisted in improving the EBG antenna performances by using a more efficient feed. The replacement of the usual microstrip patch by a horn allowed to double the radiation bandwidth while decreasing the sidelobes level (-15 dB) of a 24-dB EBG antenna. A metallic prototype excited by a single horn has been manufactured at 30 GHz, and the measurements agree with the simulation. This device with one feed allows good SFOCA performances, similar to those obtained with a conventional focal feed like a Potter horn.

Radiation performance of purely metallic waveguide‐fed compact Fabry–Perot antennas for space applications

AbstractMetallic electromagnetic bandgap resonator antennas are highly attractive to design very efficient primary feeds of focal array fed reflector antennas for space Tx applications. The antennas analayzed in this work consists of purely metallic Fabry–Perot (FP) cavities with a single partially reflecting surface (PRS) and four perfect electrical conductor (PEC) walls on the sides. They are excited by a standard metallic waveguide. In contrast to prior work, we focus our attention on compact FP resonators whose size is in the order of a few wavelengths in free space. Their radiation characteristics (namely, their resonant frequency, maximum directivity, aperture efficiency, and radiation bandwidth) are investigated numerically in X‐band with the finite‐difference time‐domain method. The extensive study of their radiation performance as a function of their size and grid reflectivity of the PRS, as well as the comparison with the well‐known characteristics of large FP antennas, highlight three main features that must be taken into account for an optimum design: (1) for a given grid reflectivity, the resonant frequency increases while reducing the size of the shielded resonator, (2) for a given size of the antenna there exists an optimum reflectivity maximizing the aperture efficiency, (3) at resonance, the beam radiated by a square cavity is not circularly symmetric. In particular, we have shown that, for a 2 × λo cavity, it is possible to reach a high‐aperture efficiency (ηs = 80%) over a 2.8% (−1 dB radiation) bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2216–2221, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22703

Design of Compact Dual Band High Directive Electromagnetic Bandgap (EBG) Resonator Antenna Using Artificial Magnetic Conductor

A compact high directive EBG resonator antenna operating in two frequency bands is described. Two major contributions to this compact design are using single layer superstrate and using artificial surface as ground plane. To obtain only the lower operating frequency band using superstrate layer is enough, but to extract the upper operating frequency band both superstrate layer and artificial surface as ground plane are necessary. Therefore, design of a superstrate to work in two frequency bands is very important. Initially, using appropriate frequency selective surface (FSS) structure with square loop elements, we design an optimum superstrate layer for each frequency band separately to achieve maximum directivity. Also, to design an artificial surface to work in the upper frequency band we use a suitable FSS structure over dielectric layer backed by PEC. Next, by using the idea of FSS structure with double square loop elements we propose FSS structure with modified double square loop elements, so that it operates in both of the desired operating frequency bands simultaneously. Finally, the simulation results for two operating frequency bands are shown to have good agreement with measurements.

Dual resonator 1-D EBG antenna with slot array feed for improved radiation bandwidth

A one-dimensional (1-D) electromagnetic bandgap (EBG) resonator antenna with both high gain and wide radiation bandwidth is described. The use of dual resonators in combination with an array of sources leads to a dramatic increase in the radiation bandwidth of the antenna. The effect of the dual resonators is to increase the bandwidth over which the EBG material acts as a spatial filter, while the array feed increases both the directivity and radiation bandwidth. Theoretical results for a prototype designed to operate at Ku-band are presented and shown to be in good agreement with measured results. The effect of increasing the number of array elements on directivity and radiation bandwidth is examined, and the improvements of the proposed configuration compared with a classical 1-D EBG resonator antenna with single source is presented.