980 research outputs found
UWB Electric and Magnetic Monopole Antennas
This paper summarizes our recent advances in antenna designs for ultra wideband (UWB) applications. Two types of monopoles are studied and developed in our research group. The first type belongs to the electric monopole with a circular disc fed by three different feeding structures. The second type is the magnetic monopole with an elliptical slot. The performances of these two types of antennas are evaluated in both frequency and time domains. The important design parameters for achieving optimal operations are also analyzed. It is shown that both electric and magnetic monopoles can provide ultra wide bandwidth with nearly omni-directional radiation patterns over the entire frequency band. In addition, the impulse responses of the selected antennas are shown to correspond well to the frequency domain characteristics
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
Metamaterial antennas for cognitive radio applications
Cognitive radio is one of the most promising techniques to efficiently utilize the radio frequency (RF) spectrum. As the Digital Video Broadcasting-Handheld (DVB-H) band is targeted (470-862 MHz), the size of the antenna becomes challenging. Metamaterial concept is used as a miniaturization technique. Two antennas are designed, fabricated and measured. The first one achieved multiband operation by loading it with a metamaterial unit cell. These bands are controlled by engineering the dispersion relation of the unit cell. The second one, which is a 2-lumped elements loaded antenna, achieved wideband operation through the entire DVB-H band with a planar size of 5×2 cm^2. A model is proposed to explain, through simple numerical simulations and an optimization algorithm, the behavior of these component loaded antennas (which are equivalent to metamaterial inspired electrically small antennas)
Antenna Study and Design for Ultra Wideband Communication Applications
PhDSince the release by the Federal Communications Commission (FCC) of a bandwidth of
7.5GHz (from 3.1GHz to 10.6GHz) for ultra wideband (UWB) wireless communications,
UWB is rapidly advancing as a high data rate wireless communication technology.
As is the case in conventional wireless communication systems, an antenna also plays
a very crucial role in UWB systems. However, there are more challenges in designing
a UWB antenna than a narrow band one. A suitable UWB antenna should be capable
of operating over an ultra wide bandwidth as allocated by the FCC. At the same
time, satisfactory radiation properties over the entire frequency range are also necessary.
Another primary requirement of the UWB antenna is a good time domain performance,
i. e. a good impulse response with minimal distortion.
This thesis focuses on UWB antenna design and analysis. Studies have been undertaken
covering the areas of UWB fundamentals and antenna theory. Extensive investigations
were also carried out on two different types of UWB antennas.
The first type of antenna studied in this thesis is circular disc monopole antenna. The
vertical disc monopole originates from conventional straight wire monopole by replacing
the wire element with a disc plate to enhance the operating bandwidth substantially.
Based on the understanding of vertical disc monopole, two more compact versions featuring
low-profile and compatibility to printed circuit board are proposed and studied.
Both of them are printed circular disc monopoles, one fed by a micro-strip line, while
the other fed by a co-planar waveguide (CPW).
The second type of UWB antenna is elliptical/circular slot antenna, which can also be
fed by either micro-strip line or CPW.
The performances and characteristics of UWB disc monopole and elliptical/circular slot
antenna are investigated in both frequency domain and time domain. The design parameters
for achieving optimal operation of the antennas are also analyzed extensively in
order to understand the antenna operations.
It has been demonstrated numerically and experimentally that both types of antennas
are suitable for UWB applications
Miniaturized Microwave Devices and Antennas for Wearable, Implantable and Wireless Applications
This thesis presents a number of microwave devices and antennas that maintain
high operational efficiency and are compact in size at the same time. One goal
of this thesis is to address several miniaturization challenges of antennas and
microwave components by using the theoretical principles of metamaterials,
Metasurface coupling resonators and stacked radiators, in combination with the
elementary antenna and transmission line theory. While innovating novel
solutions, standards and specifications of next generation wireless and
bio-medical applications were considered to ensure advancement in the
respective scientific fields. Compact reconfigurable phase-shifter and a
microwave cross-over based on negative-refractive-index transmission-line
(NRI-TL) materialist unit cells is presented. A Metasurface based wearable
sensor architecture is proposed, containing an electromagnetic band-gap (EBG)
structure backed monopole antenna for off-body communication and a fork shaped
antenna for efficient radiation towards the human body. A fully parametrized
solution for an implantable antenna is proposed using metallic coated stacked
substrate layers. Challenges and possible solutions for off-body, on-body,
through-body and across-body communication have been investigated with an aid
of computationally extensive simulations and experimental verification. Next,
miniaturization and implementation of a UWB antenna along with an analytical
model to predict the resonance is presented. Lastly, several miniaturized
rectifiers designed specifically for efficient wireless power transfer are
proposed, experimentally verified, and discussed. The study answered several
research questions of applied electromagnetic in the field of bio-medicine and
wireless communication.Comment: A thesis submitted for the degree of Ph
Comparative study of micromixers for laminar blood mixing
Miniaturization is the trend in analytical chemistry and life science. It has been
emerging into the research field of microfluidics in the application of LOC. The
application is used for biochemistry analysis and require a rapid mixing in small area.
Due to laminar flow (Reynold Number < 1) passive micromixer is the best method in
fluids mixing. Passive micromixer also depend on the channel geometry for mixing
effectiveness. In this study, four different micromixers were evaluated based on the
baseline control Y-micromixer. The micromixers are internal rib micromixer, patterned
grooves micromixer, obstruction micromixer and slanted rib micromixer. These
micromixer has 1000μm channel length, 150μm inlet length, 90o between inlets ports,
width and depth are 40μm each. The fluids used for mixing were blood which has 1.0 ×
10-6 kg/μms of viscosity and toluene which has low viscosity than blood (0.664 × 10-9
kg/μms). The fluids used to evaluate the differences in term of their visual performance
based image’s standard deviation by plotting the graph and mixing efficiency by
calculation. Based on these evaluations, the slanted rib micromixer is the best
micromixer design with the highest mixing efficiency of 99.85% at the outlet of the
channel
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
- …