Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Towards Accurate Dielectric Property Retrieval of Biological Tissues for Blood Glucose Monitoring

(c) 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.This post-acceptance version of the paper is essentially complete, but may differ from the official copy of record, which can be found at the following web location (subscription required to access full paper): http://dx.doi.org/10/1109/TMTT.2014.2365019

2009 Index IEEE Antennas and Wireless Propagation Letters Vol. 8

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

A study of planar inverted-F antennas in a dielectric enclosure

Demand for small and low-profile antennas has greatly increased due to the desire for miniaturisation of modern-day mobile radio electronic terminals. Such an antenna is often integrated into the dielectric casing of a terminal, or independently enclosed within a dielectric radome to provide a protection from operating environments and keep the system more compact. However, the dielectric casing or radome may interact strongly with the antenna and result in losses in performance. The primary focus of this dissertation is to investigate and enhance the performance of Planar Inverted-F Antennas (PIFAs) when enclosed in dielectric casings or radomes for applications in mobile radio communications. PIFAs have attracted much interest due to their small volume, low profile structures and electrical characteristics compatible with existing specifications, making it a promising candidate for mobile radio applications. Therefore, the design of a single band PIFA on a finite ground plane, operating in the 900 MHz band is first presented. It is found that the effect of the finite ground plane must be considered to achieve an optimum performance of the PIFA. Then the performance of this antenna in the presence of a dielectric cover layer is investigated and evaluated in terms of resonant frequency, bandwidth and efficiency. In this study, the dielectric layer represents the dielectric casing of a device where the antenna is much closer to the top part of the casing than to the other side parts whose effect can then be ignored. Computer simulations of performance are based on the Method of Moments (MOM) and have been validated by measurements. This study shows that a dielectric cover layer will strongly interact with the antenna with the result that the antenna performance may move outside the design specifications.Therefore, it is concluded that the dielectric cover layer must always be taken into account in the design stage. In addition, the input and radiation characteristics of a PIFA enclosed within a rectangular dielectric radome for both the 900 MHz and 2400 MHz frequency bands are analysed using the MOM. This research concentrates on the effect of each individual part of the rectangular dielectric radome on the overall performance. It is observed that each individual part has a different degree of effect on both the input and radiation characteristics of the PIFA, and that the effect is more significant at the higher frequency band. The study indicates that the effect of the dielectric radome on the performance of the antenna can be minimised by carefully choosing its location and orientation within the radome. Another indication is that an optimised dielectric radome design can both miniaturise the antenna and at the same time improve the bandwidth without sacrificing other performance parameters such as the gain. Furthermore, an analytical approach based on the Transmission Line Model (TLM) is applied to estimate the input characteristics of a PIFA having a dielectric cover layer. The results calculated based on this approach are compared with MOM computed results. A reasonably good agreement between them has been demonstrated. It is suggested that the TLM model could form part of an efficient Computer Aided Design (CAD) tool for design engineers to provide initial design parameters.Finally, a new dual-band PIFA is proposed. A design example for the Industrial, Scientific and Medical (ISM) frequency bands of 900 MHz and 2400 MHz is given. Measurement validation of the design is presented. The influence of the dielectric cover layer on the resonant frequency, bandwidth, gain and radiation patterns of this antenna is also examined by simulation. In this study, it is found that a simple capacitive disk arrangement not only provides a single feed for dual-band operation but also gives flexibility to allow individual control of the two desired band resonances

2008 Index IEEE Transactions on Control Systems Technology Vol. 16

This index covers all technical items - papers, correspondence, reviews, etc. - that appeared in this periodical during the year, and items from previous years that were commented upon or corrected in this year. Departments and other items may also be covered if they have been judged to have archival value. The Author Index contains the primary entry for each item, listed under the first author\u27s name. The primary entry includes the coauthors\u27 names, the title of the paper or other item, and its location, specified by the publication abbreviation, year, month, and inclusive pagination. The Subject Index contains entries describing the item under all appropriate subject headings, plus the first author\u27s name, the publication abbreviation, month, and year, and inclusive pages. Note that the item title is found only under the primary entry in the Author Index

Size reduction of microstrip antennas using left-handed materials realized by complementary split-ring resonators

Recently, metamaterials (MTMs) engineered to have negative values of permittivity and permeability, resulting in a left-handed system, have provided a new frontier for microwave circuits and antennas with possibilities to overcome limitations of the right-handed system. Microwave circuit components such as waveguides, couplers, power dividers and filters, constructed on left-handed materials, have demonstrated properties of backward coupling, phase compensation, reduced sizes, and propagation of evanescent modes. However, there is very limited work to date, on the microstrip antennas with metamaterials. Microstrip antenna is widely used for its low-profile, simplicity of feed and compatibility with planar microstrip circuitry. As the trend towards miniaturization of electronic circuitry continues, antennas remain as the bulkiest part of wireless devices. There are three primary objectives to the present work: 1. Explore the possibility of miniaturizing microstrip patch antennas using left-handed materials through phase-compensation 2. Achieve negative permittivity using Complementary Split-Ring Resonators (CSRR) 3. Implement CSRR in the ground plane of a rectangular patch antenna, and validate through simulation and measurement A rectangular patch antenna with a combined DPS-DNG substrate has been analyzed with the cavity model, from which the condition for mode propagation has been derived. Criteria for ‘electrically small’ patch, using phase-compensation have been developed and propagating modes that satisfy these criteria have been obtained. With an objective to design practically realizable antennas, amongst several available LHM structures, the Complementary Split Ring Resonators (CSRR) has been chosen, primarily for the ease of implementation in the ground plane. CSRRs are periodic structures which alter the bulk effective permittivity of a host medium in which they are embedded. The effective permittivity becomes negative in a certain frequency band defined as a ‘stop-band’. In the present work the frequency response of the CSRR and the ‘stop-band’ has been determined using a full wave solver, from which, effective permittivity of the composite with CSRRs has been obtained by parameter extraction. Finally, several combinations of patch and CSRR in the ground plane have been designed and constructed in the X-band frequency range. Measurements of input characteristics and directivity have been validated through simulation by Ansoft Designer and HFSS. It has been observed that the best designs are achieved when the ‘stop-band’ of the CSRR corresponds to the desired resonant frequency of the antenna. Under these conditions, a size reduction of up to fifty percent has been achieved and it is noted that the back lobe is negligible and the directivity is comparable to that of a right-handed microstrip antenna

BANDWIDTH AND GAIN ENHANCEMENT OF MICROSTRIP ANTENNA USING DEFECTED GROUND STRUCTURE AND HORIZONTAL PATCH GAP

This research proposed microstrip antenna design using the Defected Ground Structure (DGS) and horizontal patch gap (HPG) for bandwidth and enhancement purposes. This design is to reduce the weakness of a microstrip antenna, which has small gain and narrow bandwidth. The design was simulated in CST Microwave Studio with a working frequency of 2.4 GHz. The design consists of three stages model, i.e., conventional design, DGS modification, and the combination DGS using a Horizontal Patch Gap (DGSHPG). The radius of the conventional circular patch is 16.7 mm. The substrate has 4.6 of dielectric constant, 1.6 of substrate height, and 0.025 of the loss tangent. The simulation results show that the DGS design produces more bandwidth and gain than a conventional design, where the bandwidth and gain improvement are 421.2 MHz and 1.73 dB, respectively. The DGS model is combined with a gap that separates the circular patch (DGSHPG) to achieve the optimum design. The results show the bandwidth and gain improvement of more than 50% and 18.1% compared to the DGS design, respectively. Other parameter performance also shows improvement, such as a reflection factor with -53.3 dB at the center frequency. The physical change also influences the patch’s radius, where it is reduced around 1.4 mm or 8.4% from the original design. Overall, the proposed design has succeeded in achieving bandwidth and gain enhancement and reducing the patch dimension

Balanced dual-segment cylindrical dielectric resonator antennas for ultra-wideband applications.

yesIn this paper, balanced dual segment cylindrical dielectric antennas (CDRA) with ultra wide-band operation are reported. First a T-shaped slot and L-shaped microstrip feeding line are suggested to furnish a balanced coupling mechanism for feeding two DRAs. Performance of the proposed antenna was analyzed and optimized against the target frequency band. The proposed antenna was then modified by adding a C-shaped strip to increase the gain. The performances of both balanced antennas were characterized and optimized in terms of antenna reflection coefficient, radiation pattern, and gain. The antennas cover the frequency range from 6.4 GHz to 11.736 GHz, which is 58.7% bandwidth. A maximum gain of 2.66 dB was achieved at a frequency of 7 GHz with the first antenna, with a further 2.25 dB increase in maximum gain attained by adding the C-shaped strip. For validation, prototypes of the two antennas were fabricated and tested. The predicted and measured results showed reasonable agreement and the results confirmed good impedance bandwidth characteristics for ultra-wideband operation from both proposed balanced antennas

Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review

Advances in reflectarrays and array lenses with electronic beam-forming capabilities are enabling a host of new possibilities for these high-performance, low-cost antenna architectures. This paper reviews enabling technologies and topologies of reconfigurable reflectarray and array lens designs, and surveys a range of experimental implementations and achievements that have been made in this area in recent years. The paper describes the fundamental design approaches employed in realizing reconfigurable designs, and explores advanced capabilities of these nascent architectures, such as multi-band operation, polarization manipulation, frequency agility, and amplification. Finally, the paper concludes by discussing future challenges and possibilities for these antennas.Comment: 16 pages, 12 figure