Theory of Controlled Aperture Field for Advanced Superstrate Design of a Resonance Cavity Antenna With Improved Radiations Properties
TL;DR: This work demonstrates an interesting transformation of a metal superstrate from rectangle to an ellipse or anEllipse-circle combination to achieve significant improvements in the aperture fields and hence the sidelobe level (SLL).
Abstract: An insight based on a new theoretical approach has been developed to facilitate the design of a superstrate which plays a key role in realizing a high gain resonance cavity antenna (RCA). The work is aimed to address a profound theoretical basis of controlling the aperture fields by proper shaping of superstrate and to apply it to alleviate the earlier shortcomings along with further improvement in radiation characteristics. This demonstrates an interesting transformation of a metal superstrate from rectangle to an ellipse or an ellipse-circle combination to achieve significant improvements in the aperture fields and hence the sidelobe level (SLL). The antenna characteristics have been verified using simulated data followed by experiments using different sets of prototypes. About 50% reduction in size along with an improvement in the SLL by 5–17 dB compared to its immediate predecessor has been experimentally demonstrated. Proposed theory should find the potential applications in conceiving efficient RCA designs in the future.
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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.
55 citations
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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).
50 citations
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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%.
37 citations
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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%.
22 citations
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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.
21 citations
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References
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Book•
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01 Jan 1982
TL;DR: The most up-to-date resource available on antenna theory and design as mentioned in this paper provides an extended coverage of ABET design procedures and equations making meeting ABET requirements easy and preparing readers for authentic situations in industry.
Abstract: The most-up-to-date resource available on antenna theory and design Expanded coverage of design procedures and equations makes meeting ABET design requirements easy and prepares readers for authentic situations in industry New coverage of microstrip antennas exposes readers to information vital to a wide variety of practical applicationsComputer programs at end of each chapter and the accompanying disk assist in problem solving, design projects and data plotting-- Includes updated material on moment methods, radar cross section, mutual impedances, aperture and horn antennas, and antenna measurements-- Outstanding 3-dimensional illustrations help readers visualize the entire antenna radiation pattern
14,060 citations
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Book•
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01 Dec 1950
TL;DR: In this article, Lehto and Vainikainen discuss the relationship between aperture distribution and far-field pattern and the Fourier Transform Relation between Aperture Distribution and Far-Field Pattern.
Abstract: 1 Introduction 2 Antenna Basics 3 The Antenna Family 4 Point Sources 5 Arrays of Point Sources 6 The Electric Dipole and Thin Linear Antennas 7 The Loop Antenna 8 End Fire Antennas: The Helical Beam Antenna and the Yagi-Uda Array 9 Slot, Patch and Horn Antennas 9II Slot and Horn Antennas II 10 Flat Sheet, Corner and Parabolic Reflector Antennas 11 Broadband and Frequency-Independent Antennas 12 Antenna Temperature, Remote Sensing and Radar Cross-Section 13 Self and Mutual Impedances 14 The Cylindrical Antenna and the Moment Method (MM) 15 The Fourier Transform Relation Between Aperture Distribution and Far-Field Pattern 16 Arrays of Dipoles and of Apertures 17 Lens Antennas 18 Frequency-Selective Surfaces and Periodic Structures by Ben A. Munk 19 Practical Design Considerations of Large Aperture Antennas 20 Some Examples of Large or Unique Antennas 21 Antennas for Special Applications 22 Terahertz Antennas 23 Baluns, etc. By Ben A. Munk 24 Antenna Measurements. By Arto Lehto and Pertti Vainikainen Appendix A Tables for Reference Appendix B Books and Video Tapes Appendix C Computer Programs (Codes) Appendix D Absorbing Materials Appendix E Measurement Error
1,072 citations
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TL;DR: In this paper, the authors investigated the effect of placing a partially reflecting sheet in front of an antenna with a reflecting screen at a wavelength of 3.2 cm and showed that large arrays produce considerably greater directivity but their efficiency is poor.
Abstract: Multiple reflections of electromagnetic waves between two planes are studied, and the increase in directivity that results by placing a partially reflecting sheet in front of an antenna with a reflecting screen is investigated at a wavelength of 3.2 cm. The construction and performance of various models of such arrays is discussed. Thus, for example, a "reflex-cavity antenna" with an outer diameter of 1.88 \lambda and an over-all length of only 0.65 \lambda is described which has half-power beamwidths of 34\deg and 41\deg in the E and H planes, respectively, and a gain of approximately 14 db. It is shown that larger systems produce considerably greater directivity but that their efficiency is poor.
832 citations
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TL;DR: In this article, a ray analysis is employed in order to give physical insight into the performance of AMCs and derive design guidelines, and the bandwidth and center frequency of AMC surfaces are investigated using full-wave analysis and the qualitative predictions of the ray model are validated.
Abstract: Planar periodic metallic arrays behave as artificial magnetic conductor (AMC) surfaces when placed on a grounded dielectric substrate and they introduce a zero degrees reflection phase shift to incident waves. In this paper the AMC operation of single-layer arrays without vias is studied using a resonant cavity model and a new application to high-gain printed antennas is presented. A ray analysis is employed in order to give physical insight into the performance of AMCs and derive design guidelines. The bandwidth and center frequency of AMC surfaces are investigated using full-wave analysis and the qualitative predictions of the ray model are validated. Planar AMC surfaces are used for the first time as the ground plane in a high-gain microstrip patch antenna with a partially reflective surface as superstrate. A significant reduction of the antenna profile is achieved. A ray theory approach is employed in order to describe the functioning of the antenna and to predict the existence of quarter wavelength resonant cavities.
814 citations
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TL;DR: In this article, a leaky-wave analysis is used to explain the narrow-beam resonance gain phenomenon in which narrow beams may be produced from a printed antenna element in a substrate-superstrate geometry.
Abstract: A leaky-wave analysis is used to explain the narrow-beam resonance-gain phenomenon in which narrow beams may be produced from a printed antenna element in a substrate-superstrate geometry. It is demonstrated that the phenomenon is attributable to the presence of both transverse electric and transverse magnetic-mode leaky waves, that are excited on the structure. Asymptotic formulas for the leaky wave are compared with the exact patterns to demonstrate the dominant role of the leaky waves in determining the pattern. Results are presented as a function of frequency, the scan angle, and the permittivity of the superstrate. >
308 citations
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