Synthesizing Aperture Fields Over the Superstrate of Resonance Cavity Antenna for Modifying Its Radiation Properties
TL;DR: In this article, a new approach of aperture field synthesis over the superstrate has been proposed to improve the radiation characteristics of a resonance cavity antenna (RCA) with the aim of reducing the sidelobe level (SLL) and increasing the gain.
Abstract: Modification and improvement in the radiation characteristics of a resonance cavity antenna (RCA) have been addressed from a new approach of aperture field synthesis over the superstrate. This concept has been established through a series of systematic studies, which are based on the exciting observations reported very recently by these authors. A process of modification or engineering on the superstrate has been conjectured in view of obtaining reduced sidelobe level (SLL) and/or increased gain. The same has been successfully designed and experimentally demonstrated indicating as much as 10 dB suppression in SLL along with 3 dB improvement in gain compared to its nearest contender. This study promises a potential technique in RCA design along with several attractive features.
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TL;DR: In this paper, the authors presented a design methodology for a compact low-cost partially reflecting surface (PRS) for a wideband high-gain resonant cavity antenna (RCA) which requires only a single commercial dielectric slab.
Abstract: This communication presents a design methodology for a compact low-cost partially reflecting surface (PRS) for a wideband high-gain resonant cavity antenna (RCA) which requires only a single commercial dielectric slab. The PRS has one nonuniform double-sided printed dielectric, which exhibits a negative transverse-reflection magnitude gradient and, at the same time, a progressive reflection phase gradient over frequency. In addition, a partially shielded cavity is proposed as a method to optimize the directivity bandwidth and the peak directivity of RCAs. A prototype of the PRS was fabricated and tested with a partially shielded cavity, showing good agreement between the predicted and measured results. The measured peak directivity of the antenna is 16.2 dBi at 11.4 GHz with a 3 dB bandwidth of 22%. The measured peak gain and 3 dB gain bandwidth are 15.75 dBi and 21.5%, respectively. The PRS has a radius of 29.25 mm ( $1.1\lambda _{0}$ ) with a thickness of 1.52 mm ( $0.12\lambda _{g}$ ), and the overall height of the antenna is $0.6\lambda _{0} $ , where $\lambda _{0}$ and $\lambda _{g}$ are the free-space and guided wavelengths at the center frequency of 11.4 GHz.
89 citations
TL;DR: In this paper, a hybrid topology of fully metallic spatial phase shifters is developed for the AMPCS, resulting in an extremely lower prototyping cost as that of other state-of-the-art substrate-based PCSs.
Abstract: This article addresses a critical issue, which has been overlooked, in relation to the design of phase-correcting structures (PCSs) for electromagnetic bandgap (EBG) resonator antennas (ERAs). All the previously proposed PCSs for ERAs are made using either several expensive radio frequency (RF) dielectric laminates or thick and heavy dielectric materials, contributing to very high fabrication cost, posing an industrial impediment to the application of ERAs. This article presents a new industrial-friendly generation of PCS, in which dielectrics, known as the main cause of high manufacturing cost, are removed from the PCS configuration, introducing an all-metallic PCS (AMPCS). Unlike existing PCSs, a hybrid topology of fully metallic spatial phase shifters are developed for the AMPCS, resulting in an extremely lower prototyping cost as that of other state-of-the-art substrate-based PCSs. The APMCS was fabricated using laser technology and tested with an ERA to verify its predicted performance. The results show that the phase uniformity of the ERA aperture has been remarkably improved, resulting in 8.4 dB improvement in the peak gain of the antenna and improved sidelobe levels (SLLs). The antenna system including APMCS has a peak gain of 19.42 dB with a 1 dB gain bandwidth of around 6%.
72 citations
TL;DR: In this paper, an approach to correcting electric near-field phase and magnitude over a wideband for Fabry-Perot resonator antennas (FPRAs) is presented, where a time-average Poynting vector in conjunction with a phase gradient analysis is utilized to suggest the initial configuration of the NFCS for wideband performance.
Abstract: A systematic approach to correcting electric near-field phase and magnitude over a wideband for Fabry–Perot resonator antennas (FPRAs) is presented. Unlike all other unit-cell-based near-field correction techniques for FPRAs, which merely focus on phase correction at a single frequency, this method delivers a compact near-field correcting structure (NFCS) with a wide operational bandwidth of 40%. In this novel approach, a time-average Poynting vector in conjunction with a phase gradient analysis is utilized to suggest the initial configuration of the NFCS for wideband performance. A simulation-driven optimization algorithm is then implemented to find the thickness of each correcting region, defined by the gradient analysis, to complete the NFCS design. According to the predicted and measured results, the phase and magnitude distributions of the electric near field have been greatly improved, resulting in a high aperture efficiency of 70%. The antenna under NFCS loading has a peak measured directivity of 21.6 dB, a 3 dB directivity bandwidth of 41% and a 10 dB return loss bandwidth of 46%, which covers the directivity bandwidth. The diameter of the proposed NFCS is $3.8\lambda _{0c}$ , which is around half that of all the other unit-cell-based phase-correcting structures, where $\lambda _{0c}$ is the free-space wavelength at the central frequency of the NFCS (13.09 GHz).
67 citations
Cites methods from "Synthesizing Aperture Fields Over t..."
...This new design procedure offers more flexibility in the adjustment of the FPRAs’ aperture field, such as sidelobe levels (SLLs) reduction [12]....
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TL;DR: The AMPS has remarkably improved the radiation performance of ERA by increasing its far-field directivity from 12.67 dB to 21.12 dB and reducing side-lobe level from −7.3 dB to −17.2 dB.
Abstract: Additively manufactured perforated superstrate (AMPS) is presented to realize directive radio frequency (RF) front-end antennas. The superstrate comprises spatially distributed dielectric unit-cell elements with square perforations, which creates a pre-defined transmission phase delay pattern in the propagating electric field. The proposed square perforation has superior transmission phase characteristics compared to traditionally machined circular perforations and full-wave simulations based parametric analysis has been performed to highlight this supremacy. The AMPS is used with a classical electromagnetic-bandgap resonator antenna (ERA) to improve its directive radiation characteristics. A prototype is developed using the most common, low-cost and easily accessible Acrylonitrile Butadiene Styrene (ABS) filament. The prototype was rapidly fabricated in less than five hours and weighs 139.3 g., which corresponds to the material cost of only 2.1 USD. The AMPS has remarkably improved the radiation performance of ERA by increasing its far-field directivity from 12.67 dB to 21.12 dB and reducing side-lobe level from -7.3 dB to -17.2 dB.
38 citations
Cites methods from "Synthesizing Aperture Fields Over t..."
...In a different approach, fully reflecting surfaces have been proposed to be used in the ERAs’s configuration, which can also contribute to a better side-lobe levels as explained in [34], [35]....
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TL;DR: In this article, a double-layer non-uniform superstrate (DNS) was proposed to improve the aperture efficiency of the Fabry-Perot resonator antenna.
Abstract: Due to the nonuniform electromagnetic (EM) field amplitude distribution over its aperture, the Fabry–Perot resonator antenna (FPRA) suffers from relatively low aperture efficiency. In this communication, an FPRA with high aperture efficiency is proposed based on a double-layer nonuniform superstrate (DNS). The DNS is designed to have a constant reflection phase but a varying reflection magnitude, thereby obtaining a uniform EM field amplitude distribution over the FPRA’s aperture and, hence improving the directivity and the corresponding aperture efficiency. As an example, a cylindrical FPRA with an aperture diameter of $3.5~\lambda $ (where $\lambda $ is the wavelength in free space) is presented. In comparison with a uniform superstrate, the proposed DNS enhances the FPRA’s directivity from 19.6 to 20.4 dBi and correspondingly improves the aperture efficiency from 76.3% to 91.7%.
26 citations
Cites background from "Synthesizing Aperture Fields Over t..."
...[11] and [12] have investigated the manipulation of the FPRA’s aperture field by the nontransparent metal superstrate for improving radiation properties....
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References
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TL;DR: In this paper, a high-efficient and high-gain aperture coupled patch antenna with superstrate at 60 GHz was studied and presented, and it was shown that adding superstrate will result in a significant effect on the antenna performances, and the size of the superstrate is critical for the optimum performance.
Abstract: A high-efficient and high-gain aperture coupled patch antenna with superstrate at 60 GHz is studied and presented. It is noted that adding superstrate will result in a significant effect on the antenna performances, and the size of the superstrate is critical for the optimum performance. The maximum measured gain of a single antenna with superstrate is 14.6 dBi, which is higher than that of a classical 2 x 2 array. It is found that the gain measured of a single antenna with superstrate increases nearly 9 dB at 60 GHz over its basic patch antenna. This superstrate antenna gives a very high estimated efficiency of 76%. The 2:1 measured VSWR bandwidth with superstrate is 6.8%. The radiation patterns are found to be broadside all over the frequency band. Also, this letter explains a comparison to another source of parasitic patch superstrate antenna with normal microstrip coupling. It is found that aperture coupling is better for high-gain antenna applications.
155 citations
TL;DR: In this article, a compact high-directive EBG resonator antenna operating in two frequency bands is described, and two major contributions to this compact design are using single layer superstrate and using artificial surface as ground plane.
Abstract: 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.
105 citations
TL;DR: In this article, the authors investigated the origin of the directivity of a dipole antenna embedded in a dielectric slab Fabry-Perot cavity and showed that the focusing effect is due to the angular selection rules in the Bragg-type mirror and is directly correlated to the frequency selectivity of the cavity.
Abstract: We investigate the origin of the directivity of a dipole antenna embedded in a dielectric slab Fabry-Perot cavity. It is shown that the focusing effect is due to the angular selection rules in the Bragg-type mirror and is directly correlated to the frequency selectivity of the cavity. For a 6 GHz resonant device, having a quality factor of 100, the aperture of the beam pattern (E-H plane) is close to 12/spl deg/ in agreement with the arguments based on frequency and angular selectivities. Hence, this kind of cavity could be used in free-space based communication links.
90 citations
"Synthesizing Aperture Fields Over t..." refers background in this paper
...Their gain enhancement was explained by the principle of a Fabry–Perot cavity [1] or leaky waves [2]....
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...The superstrate layer is normally made of metal, dielectric, or a composite structure, and the primary radiator is realized by hertzian dipole [1], microstrip patch [2]–[4], or dielectric resonator antenna (DRA) [5], [6]....
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...R ESONANCE cavity antenna (RCA) is primarily known for its high gain characteristics [1]–[12]....
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TL;DR: In this article, a fast analytical solution for the radiation field of a microstrip antenna loaded with a generalized superstrate is proposed using the cavity model of microstrip antennas in conjunction with the reciprocity theorem and the transmission line analogy.
Abstract: A fast analytical solution for the radiation field of a microstrip antenna loaded with a generalized superstrate is proposed using the cavity model of microstrip antennas in conjunction with the reciprocity theorem and the transmission line analogy. The proposed analytical formulation for the antenna's far-field is much faster when compared to full-wave numerical methods. It only needs 2% of the time acquired by full-wave analysis. Therefore the proposed method can be used for design and optimization purposes. The method is verified using both numerical and experimental results. This verification is done for both conventional dielectric superstrates, and also for artificial superstrates. The analytical formulation introduced here can be extended for the case of a patch antenna embedded in a multilayered artificial dielectric structure. Arguably, the proposed analytical technique is applied for the first time for the case of a practical microstrip patch antenna working in the Universal Mobile Telecommunications System (UMTS) band and covered with a superstrate made of an artificial periodic metamaterial with dispersive permeability and permittivity.
57 citations
"Synthesizing Aperture Fields Over t..." refers background in this paper
...A wide variety of superstrate geometry has been explored, which includes metal surface grids [3], [6], dielectric slab [4], [5], double-negative and engineered materials [7]–[10], and frequency selective surfaces [11]....
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TL;DR: In this article, a resonance cavity antenna (RCA) employing nontransparent solid metal sheet as superstrate is proposed for the first time, and the proposed configuration is much advantageous in terms of design, simplicity, structural stability, fabrication, and cost without compromising in gain, efficiency, and bandwidth.
Abstract: A resonance cavity antenna (RCA) has been explored employing nontransparent solid metal sheet as superstrate which, to the best of our knowledge, is reported for the first time. The proposed configuration is much advantageous in terms of design, simplicity, structural stability, fabrication, and cost without compromising in gain, efficiency, and bandwidth. A probe-fed dielectric resonator antenna (DRA) with ${\boldsymbol{\varepsilon} _r} = {\bf 10}$ has been used as the primary radiator. Proposed RCA bearing overall size ${\bf 1}.{\bf 1}{\boldsymbol{\lambda}} \times {\bf 1}.{\bf 1}{\boldsymbol{\lambda}} \times {\bf 0}.{\bf 6}{\boldsymbol{\lambda}}$ promises for large impedance bandwidth ( ${\sim} {\bf 23}\% $ ) with considerably high gain (11.8–12.2 dBi). The superstrate size is relatively compact compared to its semitransparent versions, investigated earlier. Present design has been experimentally validated indicating as much as 12 dBi peak gain with more than 96.5% efficiency.
52 citations
"Synthesizing Aperture Fields Over t..." refers background or result in this paper
...It, therefore, deals with a twofold objective: 1) to establish the fact of redistributing the aperture field for the benefit of radiation characteristics; and 2) to reduce SLL and enhance the gain of configuration [12]....
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...The rest of the antenna configuration follows that in [12] and allows direct comparison to building up a physical insight....
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...R ESONANCE cavity antenna (RCA) is primarily known for its high gain characteristics [1]–[12]....
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...Very recently, an alternative insight has been conceived and proposed by the present authors [12]....
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...In [12], the radiation characteristics were explained as a result of “inverse taper”-type aperture field over a solid metal sheet superstrate....
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