We propose a novel configuration of a triple band‐notched ultra‐wideband (UWB) antenna. The designed structure is based on an elliptical monopole antenna combined with a complementary split ring resonator (CSRR) structure and a spiral resonator. The spiral resonator can achieve the dual‐band notched performance at WiMAX band and ITU 8 GHz by adjusting the length and width of a spiral line. Besides, the CSRR can obtain the notched band at WLAN 5 GHz by changing the radius of a ring slot. The designed antenna shows that a VSWR of less than 2 was satisfied with a resonant frequency in the range of 1.34–11.4 GHz with a 78.96%, except for triple notched bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:4–6, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27275
A sensing probe for medical imaging diagnostic systems is presented. The proposed probe consists of a double-ridged waveguide (DRWG) filled with dielectric ceramic and an aperture with a tapered ridge. The DRWG is used to suppress higher-order mode radiations in the rectangular waveguide. The proposed probe is designed for broadband sensing in an immersion liquid with a complex dielectric constant. The performance of the fabricated probe successfully covers the frequency band of 3-6 GHz. The probe suppresses higher-order modes and provides symmetric and similar radiation patterns within the operating frequency range.Introduction: Microwave imaging offers a cost-effective and safe imaging procedure for medical diagnostic applications that avoids the risks of ionising radiation. In microwave tomography (MT) for breast cancer detection, microwave signals are transmitted towards the breast tissue by a sensing probe array surrounding the breast, the scattered signals from the breast are measured and the quantitative maps of the dielectric properties throughout the breast volume are reconstructed by solving electromagnetic inverse scattering problems [1, 2].The high-quality MT image depends on an accurate numerical model of the forward solver. The computational cost and numerical error due to the complex solver model are reduced by making the design probe as simple as possible. The sensing probe has an impact on the accuracy of the MT system. Measurement of the undistorted signals from the breast requires a probe that can provide symmetric and similar radiation patterns within the whole frequency operation. In addition, the probe needs to operate in an immersion liquid that enhances the transmission efficiency of the microwave signals into and out of the breast tissue [1,2].In this Letter, a sensing probe for medical imaging with broadband characteristic is proposed. The proposed probe consists of a doubleridged waveguide (DRWG) filled with dielectric ceramic and an aperture with a tapered ridge. The DRWG structure is simple and stable, owing to its solid. It can be used as a probe in the measurement systems. In addition, the DRWG probe can provide suppression of the higher-order mode radiations and overcome these distortion patterns within the whole frequency operation.background liquid
Radio reception relies on the medium which determines the propagation characteristics of the electromagnetic fields carrying the information. The permittivity varies greatly depending on the medium, but it remains nearly constant, except when magnetic materials are used. For this reason, magnetic fields, typically affected by permeability, can be utilized in microwave challenging environments. In this paper, a new approach based on the giant magnetoimpedance (GMI) effect is presented. The proposed GMI-based receiver has an effective double-superheterodyne topology, where "effective" means that the receiver actually has a single mixer but appears to have added a virtual mixer due to the GMI effect. The magnetic field-tovoltage conversion ratio (MVCR), the spurious free dynamic range (SFDR) and the receiver sensitivity are characterized, and from these results the optimal operating conditions of the fabricated receiver are obtained. Additionally, wireless digital communication using on-off keying (OOK) is demonstrated and transmitted and received waveforms are compared, with the final demodulation result of the receiver showing that the transmitted digital data are precisely extracted.
This paper presents an experimental measurement system for 3-6 GHz microwave tomography (MT) of the breast. The measurement system is constructed as a minimal test bed to verify key components such as the sensing antennas, radio frequency (RF) transceiver, sensing mechanism, and image reconstruction method for our advanced MT system detecting breast cancer at an early stage. The test bed has eight RF channels operating at 3 to 6 GHz for high spatial resolution and a two-axis scanning mechanism for three-dimensional measurement. The measurement results from the test bed are shown and discussed.
This study is a computational study on focused microwave thermotherapy for knee pathological treatment using the time reversal (TR) principle in musculoskeletal disorders. The authors presented a modified TR algorithm with amplitude compensation for an accurate beam focusing of the knee tumour location in a lossy medium. Furthermore, they proposed a new approach called the truncated threshold method, which could be used to apply an effective beam focusing on a tumour location in the knee while the unwanted hot spots are controlled in the normal tissue region. Compared to the other existing methods, this new approach has the advantages of being implemented simply in the unwanted hot spot control and having a similar performance to the beam focusing on the target location. The application of the proposed algorithm and the new hot spot control method to knee pathological tissue achieved acceptable electromagnetic (EM) and thermal results. The anatomical based two‐dimensional (2D) knee model for the simulation analysis was implemented using a segmentation result of the Korean human body model obtained from magnetic resonance imaging. 2D finite‐difference time‐domain electromagnetic and thermal solvers were developed and applied to conduct the 915 MHz focused microwave thermotherapy for knee pathological treatment.
This paper presents a new application field of a giant magneto-impedance (GMI) sensor. It shows valuable findings for the GMI sensor on the possibility of a new receiving element in magnetic field communication. The proposed GMI sensors serve as antennas and mixers in receiver systems. They have the advantage of being easily implemented and in terms of mass production and manufacturing processes due to the manufacture base on a printed circuit board (PCB). Their smaller size, lower cost, and higher sensitivity have more advantages than conventional magnetic sensors, such as the magneto-inductive, anisotropic magneto-resistive, and giant magneto-resistive sensors. Two types of PCB-based GMI sensors are proposed. The first type of GMI sensor is directly wound around the solenoid-shaped pickup coil onto an alumina insulation tube inserted with an amorphous microwire. The second type of GMI sensor has a patterned pickup coil that does not require the winding of the coil, similar to the patterned pickup coil of a micro electro-mechanical system-based GMI sensor. This GMI sensor provides a new geometry that can be easily manufactured with two PCB substrates. The proposed GMI sensors achieve the equivalent magnetic noise spectral density to the high-sensitivity characteristics of the pT/√Hz level. The equivalent magnetic noise spectral density of 1.5 pT/√Hz at 20.03 MHz is obtained for the first type of GMI sensor, and 3 pT/√Hz at 3.03 MHz is achieved the second type. The analyzed results of the bandwidth and the channel capacity for the two types of GMI sensors are acceptable. This first analysis confirms the possibility of the implementation of GMI sensors in magnetic field communication. The results of this experiment confirm the high performance of the proposed GMI sensors and their applicability in magnetic field communication. The detailed experimental results of the proposed GMI sensors are presented and discussed. INDEX TERMS Amorphous microwire, giant magneto-impedance (GMI), high sensitivity, magnetic field communication, magnetic sensor.
In this article, a new configuration of a broadband antenna is proposed. The designed antenna is an elliptical monopole antenna with a complementary split ring resonator structure that is inserted in the ground plane for rejecting the 5-GHz WLAN band (5. . In addition, impedance matching technique implemented by rectangular slot applied to the ground plane is suggested. The technique can be an effective method to achieve the wider bandwidth. The designed antenna shows that a VSWR less than 2 was satisfied with a resonant frequency in the range of 2.67-12 GHz.
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