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Broadband Wearable Microstrip Antenna for Brain Detection
Abstract
Rapid mobile communication technology development has brought tremendous convenience to society. With people's increasing hunger for the improvement of quality of life, the term body-centric wireless network has gradually entered everyone's vision. The so-called human body centre wireless network is a wireless network cantered on the human body. Various devices are interconnected through this wireless network with abundant functions. At the same time, in order not to cause inconvenience to users, these devices are generally divided functional modules, some of which are implanted into the human body, and some are wearable. Therefore, the application of the human body center wireless network will inevitably bring incredible changes to the medical, military equipment, personal identification, navigation, entertainment, and other industries. Compared with CT, MRI, and other traditional detection technologies, the wearable brain detection system based on microwave imaging technology is characterized by low cost and portability. In a microwave imaging system, antenna, as a front-end device for sending and receiving RF signals, is a key element, and its performance is crucial to the imaging effect. To make the imaging effect more obvious and the detection system more convenient to carry, the microwave stroke detection system puts forward requirements for the antenna: ultra-wideband, miniaturization, low profile, low-frequency band, and vertical or directional radiation. Meanwhile, the antenna should be able to achieve good conformation with the human brain, so the flexible antenna with vertical radiation or directional radiation should be designed to make the antenna have good bendability so that it can be more easily embedded into the wearable system. This paper is divided into four parts. First, the background of the microwave brain detection status is introduced. The second part describes the theoretical knowledge of the microstrip antenna, including the concept of microstrip antenna, type, feeding mode, and main electrical parameters of the antenna. The third part introduces the concrete method and step of the antenna design and analyzes the simulation image. The simulation software platform used in this project was developed by an American company. HFSS is a three-dimensional electromagnetic simulation software platform. The fourth part describes the brain structure and flexible materials, according to the real environment, design the antenna, and get performance simulation.
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In this contribution we present two practical implementation cases of single patch antennas at 28GHz and 60GHz. We describe the design challenge of conciliating the antenna performance specifications and fabrication restrictions. Over this basic element of an array antenna we discuss the influence of three different categories of design issues.
Electronic Textiles (e-textiles) are fabrics that feature electronics and interconnections woven into them, presenting physical flexibility and typical size that cannot be achieved with other existing electronic manufacturing techniques. Components and interconnections are intrinsic to the fabric and thus are less visible and not susceptible of becoming tangled or snagged by surrounding objects. E-textiles can also more easily adapt to fast changes in the computational and sensing requirements of any specific application, this one representing a useful feature for power management and context awareness. The vision behind wearable computing foresees future electronic systems to be an integral part of our everyday outfits. Such electronic devices have to meet special requirements concerning wearability. Wearable systems will be characterized by their ability to automatically recognize the activity and the behavioral status of their own user as well as of the situation around her/him, and to use this information to adjust the systems' configuration and functionality. This review focuses on recent advances in the field of Smart Textiles and pays particular attention to the materials and their manufacturing process. Each technique shows advantages and disadvantages and our aim is to highlight a possible trade-off between flexibility, ergonomics, low power consumption, integration and eventually autonomy.
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To address the need for fundamental universally valid definitions of exact bandwidth and quality factor (Q) of tuned antennas, as well as the need for efficient accurate approximate formulas for computing this bandwidth and Q, exact and approximate expressions are found for the bandwidth and Q of a general single-feed (one-port) lossy or lossless linear antenna tuned to resonance or antiresonance. The approximate expression derived for the exact bandwidth of a tuned antenna differs from previous approximate expressions in that it is inversely proportional to the magnitude |Z'<sub>0</sub>(ω<sub>0</sub>)| of the frequency derivative of the input impedance and, for not too large a bandwidth, it is nearly equal to the exact bandwidth of the tuned antenna at every frequency ω<sub>0</sub>, that is, throughout antiresonant as well as resonant frequency bands. It is also shown that an appropriately defined exact Q of a tuned lossy or lossless antenna is approximately proportional to |Z'<sub>0</sub>(ω<sub>0</sub>)| and thus this Q is approximately inversely proportional to the bandwidth (for not too large a bandwidth) of a simply tuned antenna at all frequencies. The exact Q of a tuned antenna is defined in terms of average internal energies that emerge naturally from Maxwell's equations applied to the tuned antenna. These internal energies, which are similar but not identical to previously defined quality-factor energies, and the associated Q are proven to increase without bound as the size of an antenna is decreased. Numerical solutions to thin straight-wire and wire-loop lossy and lossless antennas, as well as to a Yagi antenna and a straight-wire antenna embedded in a lossy dispersive dielectric, confirm the accuracy of the approximate expressions and the inverse relationship between the defined bandwidth and the defined Q over frequency ranges that cover several resonant and antiresonant frequency bands.
This communication presents a novel cactus-shaped Ultra Wideband (UWB) monopole antenna fabricated on Liquid Crystal Polymer (LCP). The proposed antenna is a very compact design since it can be fabricated on a board with dimensions only 20×28 mm2, while the three linear segments that comprise the cactus-shaped monopole provide a direct control on antenna matching. The proposed antenna is operating from 2.85 GHz to 11.85 GHz and it presents very consistent omni-directional patterns throughout the UWB frequency range. Return loss and pattern measurements are presented and the operation principles are discussed in detail. The simplicity of this topology, with the easily controllable return loss, allows for its easy implementation for various UWB sub-band designs, just by building suitable monopole versions, for which the only difference is the length of the three linear segments.
This paper presents a Flexible Microstrip CPW antenna that can be placed in contact with the human skin. Unlike previous flexible antennas, this antenna offers a very thin thickness (0.125mm) and small dimensions; 15mm×20 mm, that assure an easy integration into systems. A specific application of the antenna in microwave thermography in S-Band [2–4] GHz for breast cancer detection is considered. The developed design provides a bandwidth of 550MHz around 3GHz with a total gain of about 1dB. The antenna prototype has been built and carried out using CST Microwave Studio software.
Abstract The main problem in preparing stable and printable inks for the inkjet printing of textile substrates is in overcoming their roughness and high sintering temperature. In this study, the modified Tollens’ process for the preparation of a suitable water-soluble ink containing silver for the inkjet printing of textile substrates as a tool for textronic applications was adopted. The choice of this type of ink ensured inkjet printability of textile surfaces with simultaneous sintering at low temperature not exceeding 90 °C. The surface resistance of the inkjet-printed silver layers on all the textile fabrics studied steadily decreased with the number of silver layers deposited. In the case of 8 prints on synthetic textiles made of polyacrylonitrile, polypropylene, polyester and basalt fibres the surface resistance in the range 0.155-0.235 Ω/sq. was achieved. For some textile substrates made of natural fibres and their blends with synthetic fibres, to achieve the proper conductivity an interlayer of acrylic copolymer containing resin was applied. The surface resistance for the same number of prints was in the range of 0.389-0.622 Ω/sq. The study confirmed the usefulness of ink applied in printing silver electrodes and their resistance to bending, washing and dry-cleaning processes. On the basis of these findings, some potential applications in textronic systems, e.g. capacitors, textile heating actuators, textile patch antennas, and high-frequency transmission lines were proposed.
Based on fast microwave imaging techniques, this paper focus on the research of snapshot imaging radar, which can derive a high resolution image of observed scene, both in spatial domain and time domain. On the basis of imaging geometry and echo model, the paper analyzes the feasibility of microwave snapshot imaging and the restriction between spatial resolution and time resolution firstly. Then, the system constitution and data imaging processing method of snapshot radar are researched. Finally, the feasibility and parameters of snapshot imaging model and system are investigated and verified via a simple pendulum imaging experiment.
Human MR imaging to field strengths of 9.4T and higher appears to be possible according to recent data from the University of Minnesota. The Larmor wavelength in the human tissue dielectric at 400 MHz is on the order of 9cm. By conventional methods and thinking, this wavelength would preclude any possibility of achieving safe and successful human imaging. RF interference patterns from a conventional, uniform field volume coil would create severe inhomogeneities in the anatomy. RF losses to the tissue conductor and the tissue dielectric at 400 MHz would result in severe heating for conventional pulse protocols. New methods and technology being developed however at the University of Minnesota not only solve some of these problems, but actually use the short wavelength to great advantage. By controlling the currents in individual RF coil elements, in phase, gain, frequency, time, and space, the RF field can be manipulated to optimize signal from a targeted region of interest for SNR, SAR, CNR, homogeneity, or other criteria. Such "RF shimming" will be automated much like magnetic shimming is today. First examples of these new methods, technologies, and results from them will be presented and discussed in this talk
Body-centric wireless communications (BCWCs) have received a great deal of attention recently. This communication proposes a compact planar inverted-F antenna (PIFA) operating at 2.45 GHz for on-body communications. Two shorting structures and a folded ground plane are used to improve the impedance matching and decrease the size of the proposed antenna. As a result, the proposed antenna is low-profile and compact in size, and it does not change significantly when in close proximity to the human body. This communication studies the characteristics of the proposed antenna close to the arm phantom by simulation and experiments. Both simulated and measured results are in good agreement.
Miniaturization of a rectangular microstrip antenna using a magneto-dielectric substrate is discussed theoretically and experimentally. A compact magneto-dielectric substrate is designed using a metamaterial structure that can reduce the antenna dimensions by increasing the constitutive parameters of the substrate. Furthermore, the proposed structure is thin enough to be embedded in a single dielectric substrate. The area of the microstrip antenna with the proposed magneto-dielectric substrate at 2.4 GHz is reduced up to about 65% compared to a conventional dielectric microstrip antenna. The bandwidth of the miniaturized antenna is almost unchanged due to the increase of the magnetic permeability at the designed 2.4-GHz frequency. Finally, a fabricated version of the miniaturized antenna is tested and measured. The results of the measurement and simulation are in good agreement.
In this paper, we propose a design of antenna array consists of a triangular microstrip antenna elements, containing a V-shaped slot and short-circuiting wall for the stroke detection. The simulation results, which have shown the difference in return loss up to 3 dB, are quite encouraging and suggest that the proposed system is sensitive enough to detect even small changes in the brain. The sensitivity of the detection of these changes can be provided by using of reconstruction algorithm (Fhager et al. 2006) used in microwave breast cancer detection.
To the X-ray imaging system, resolution is one of the significant parameters to measure the imaging quality. In order to develop a high-resolution X-ray digital imaging system used for electronic industry, our laboratory has worked out the systemic resolution mathematical model of the X-ray imaging system. In this model, several factors are considered, such as the size of focus of the X-ray source, the double proximity focusing X-ray image intensifier and the influence of CMOS camera. Tests show the model accords with the truth. So it would have some value to the design of the similar systems.
The application, current status and principal approaches for designing ultra-wideband (UWB) technology are discussed. UWB system can be realized by system transmitting signals with instantaneous UWB spectrum or as a frequency hopping system. The instantaneous UWB can be achieved by physical transmission of very short pulses with an ultra-wide instantaneous spectrum or binary sequences of rectangular signal. It is concluded that with the development of microelectronics, the UWB systems will become more compact, cheaper and with lower power consumption.
UWB (ultra wide band) signaling is the modern art of reusing
previously allocated RF bands by hiding signals under the noise floor.
Government regulators are testing UWB emissions to ensure that adequate
protection exists to current users of the communications bands, and are
on the brink of authorizing its use. Technology basics for short-pulse
time coded UWB and for a direct sequence UWB approach are described, and
applications of UWB devices are presented. Commercial and government
uses of UWB are described. Short pulse low power techniques have enabled
practical through-the wall radars, centimeter precision 3D positioning
and communications capabilities at high data rates
A fractal is a recursively generated object having a fractional
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recursive nature of a fractal. In this article, we provide a
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with HTS causes difficulty in feeding such antennas because of the high
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are directly coupled and gas-coupled to a microstrip transmission line
have been designed and fabricated on lanthanum aluminate substrates
using Y-Ba-Cu-O superconducting thin films. Measurements from these
antennas, including input impedance, bandwidth, efficiency, and
patterns, are presented and compared with published models. The measured
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of these architectures, although the antennas suffer from narrow
bandwidths. In each case, the HTS antenna shows a substantial
improvement over an identical antenna made with normal metals
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