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A microwave sensor to safely measure quality of muscle tissue for diagnosis and screening of diseases and medical conditions characterized by fat infiltration in muscle is presented. Fat infiltration in muscle may be seen by a lower dielectric constant of muscle at microwave frequencies corresponding to the large contrast between fat and muscle tissues. A planar resonator based on a bandstop filter and optimized to noninvasively interrogate muscle in the thigh on tissue quality is proposed. Currently, a study based on clinical trials is carried out, and, here, we present a preliminary correlation between skin and fat thicknesses and rectus femoris cross sectional area (CSA) measured with ultrasound and the proposed sensor's resonance frequency. CST simulations based on the ultrasound information guide the analysis. We see that although there are signs of a potential correlation between CSA and resonance, skin and fat variability is still an issue to overcome.

A microwave sensor to safely measure quality of muscle tissue for diagnosis and screening of diseases and medical conditions characterized by fat infiltration in muscle is presented. Fat infiltration in muscle may be seen by a lower dielectric constant of muscle at microwave frequencies corresponding to the large contrast between fat and muscle tissues. A planar resonator based on a bandstop filter and optimized to noninvasively interrogate muscle in the thigh on tissue quality is proposed. Currently, a study based on clinical trials is carried out, and, here, we present a preliminary correlation between skin and fat thicknesses and rectus femoris cross sectional area (CSA) measured with ultrasound and the proposed sensor's resonance frequency. CST simulations based on the ultrasound information guide the analysis. We see that although there are signs of a potential correlation between CSA and resonance, skin and fat variability is still an issue to overcome.

Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.

Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.

Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.

Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.

Microwave-based sensing for tissue analysis is recently gaining interest due to advantages such as non-ionizing radiation and non-invasiveness. We have developed a set of transmission sensors for microwave-based real-time sensing to quantify muscle mass and quality. In connection, we verified the sensors by 3D simulations, tested them in a laboratory on a homogeneous three-layer tissue model, and collected pilot clinical data in 20 patients and 25 healthy volunteers. This report focuses on initial sensor designs for the Muscle Analyzer System (MAS), their simulation, laboratory trials and clinical trials followed by developing three new sensors and their performance comparison. In the clinical studies, correlation studies were done to compare MAS performance with other clinical standards, specifically the skeletal muscle index, for muscle mass quantification. The results showed limited signal penetration depth for the Split Ring Resonator (SRR) sensor. New sensors were designed incorporating Substrate Integrated Waveguides (SIW) and a bandstop filter to overcome this problem. The sensors were validated through 3D simulations in which they showed increased penetration depth through tissue when compared to the SRR. The second-generation sensors offer higher penetration depth which will improve clinical data collection and validation. The bandstop filter is fabricated and studied in a group of volunteers, showing more reliable data that warrants further continuation of this development.

Розвинута теорія розсіювання електромагнітних імпульсів в лінії передачи на системах зв'язаних діелектричних резонаторів різної форми та діелектричної проникності. Знайдено загальні аналітичні вирази для огинаючих імпульсів, які розсіюються на смугових та режекторних діелектричних фільтрах. Показано, що отримані вирази переходять в відомі в окремих випадках однакових резонаторів. Наведено результати розрахунків обвідної прямокутного та гауссовского імпульсів при їх розсіюванні на смугових та режекторних фільтрах терагерцового та інфрачервоного діапазонів довжин хвиль, побудованих на різноманітних діелектричних резонаторах в різноманітних лініях передачи.

The theory of scattering of electromagnetic pulses in a transmission line on systems of coupled dielectric resonators of different shapes and dielectric permittivity is developed. General analytic expressions for envelope pulses scattered on band-pass and rejection dielectric filters are obtained. It is shown that for identical resonators the expressions found in special cases become known. The results of calculating the rectangular and Gaussian pulses scattered by bandpass and bandstop filters of the terahertz and infrared wavelengths, constructed on various dielectric resonators in various transmission lines, are presented., Развита теория рассеяния электромагнитных импульсов в линии передачи на системах связанных диэлектрических резонаторов разной формы и диэлектрической проницаемости. Получены общие аналитические выражения для огибающих импульсов, рассеиваемых на полосовых и режекторных диэлектрических фильтрах. Показано, что найденные выражения переходят в известные в частных случаях одинаковых резонаторов. Приведены результаты расчета прямоугольного и гауссовского импульсов при их рассеянии на полосовых и режекторных фильтрах терагерцового и инфракрасного диапазона длин волн, построенных на различных диэлектрических резонаторах в различных линиях передачи., Розвинута теорія розсіювання електромагнітних імпульсів в лінії передачи на системах зв'язаних діелектричних резонаторів різної форми та діелектричної проникності. Знайдено загальні аналітичні вирази для огинаючих імпульсів, які розсіюються на смугових та режекторних діелектричних фільтрах. Показано, що отримані вирази переходять в відомі в окремих випадках однакових резонаторів. Наведено результати розрахунків обвідної прямокутного та гауссовского імпульсів при їх розсіюванні на смугових та режекторних фільтрах терагерцового та інфрачервоного діапазонів довжин хвиль, побудованих на різноманітних діелектричних резонаторах в різноманітних лініях передачи.

An ultra-wideband (UWB) filtering-antenna with controllable band notch is reported in this paper. The filtering-antenna consists of a modified monopole antenna and defected microstrip structure (DMS). The monopole antenna is modified using microstrip transition in the feedline and block with a triangular-shape slot on each side of the circular patch to produce wider impedance bandwidth with better return loss. The DMS is constructed using U-shaped slot etched on the feedline to provide band notch and remove WLAN band (5.1-5.8 GHz). A switch is employed in the DMS to control the created band notch. The measured results show that the proposed design exhibits a wide impedance bandwidth with controllable WLAN band rejection, realized peak gain of 4.85 dB and omnidirectional radiation pattern. Therefore, the proposed design is suitable for UWB applications.

An ultra-wideband (UWB) filtering-antenna with controllable band notch is reported in this paper. The filtering-antenna consists of a modified monopole antenna and defected microstrip structure (DMS). The monopole antenna is modified using microstrip transition in the feedline and block with a triangular-shape slot on each side of the circular patch to produce wider impedance bandwidth with better return loss. The DMS is constructed using U-shaped slot etched on the feedline to provide band notch and remove WLAN band (5.1-5.8 GHz). A switch is employed in the DMS to control the created band notch. The measured results show that the proposed design exhibits a wide impedance bandwidth with controllable WLAN band rejection, realized peak gain of 4.85 dB and omnidirectional radiation pattern. Therefore, the proposed design is suitable for UWB applications.

An ultra-wideband (UWB) filtering-antenna with controllable band notch is reported in this paper. The filtering-antenna consists of a modified monopole antenna and defected microstrip structure (DMS). The monopole antenna is modified using microstrip transition in the feedline and block with a triangular-shape slot on each side of the circular patch to produce wider impedance bandwidth with better return loss. The DMS is constructed using U-shaped slot etched on the feedline to provide band notch and remove WLAN band (5.1-5.8 GHz). A switch is employed in the DMS to control the created band notch. The measured results show that the proposed design exhibits a wide impedance bandwidth with controllable WLAN band rejection, realized peak gain of 4.85 dB and omnidirectional radiation pattern. Therefore, the proposed design is suitable for UWB applications.

Розширена теорія розсіювання електромагнітних хвиль лінії передачи на системах зв'язаних діелектричних резонаторів різної форми та діелектричної проникності. Дано нове визначення коефіцієнтів зв'язку різних діелектричних резонаторів. Отримані аналітичні вирази для коефіцієнтів взаємного зв'язку діелектричних резонаторів циліндричної та сферичної форми, виконаних із різних матеріалів. Розглянуті основні закономірності зміни зв'язку при варіації параметрів структури. Приведені результати розрахунків коефіцієнтів передачи та відбиття смугових та режекторних фільтрів, побудованих на різних діелектричних резонаторах в прямокутному та круглому хвилеводах. Встановлено найбільш оптимальні конфігурації, які дозволяють досягати найкращих характеристик розсіювання.

The theory of scattering of electromagnetic waves by systems of various coupled the different shape and variant permittivity dielectric resonators is expanded. A new definition of the coupling coefficients of different dielectric resonators is given. The analytical expressions of coupling coefficient of different cylindrical and spherical dielectric resonators made from different dielectrics are obtained. The main regularities of the change in the coupling with the variation of the structure's parameters are considered. The results of calculation of the transmission and the reflection coefficients for bandpass and bandstop filters on various dielectric resonators in the rectangular and circular waveguides are presented. Most optimal configurations, allowing to achieve the best scattering characteristics are determined., Расширена теория рассеяния электромагнитных волн линии передачи на системах связанных диэлектрических резонаторов разной формы и диэлектрической проницаемости. Дано новое определение коэффициентов связи различных диэлектрических резонаторов. Получены аналитические выражения для коэффициентов связи диэлектрических резонаторов цилиндрической и сферической формы, выполненных из различных материалов. Рассмотрены основные закономерности изменения связи при вариации параметров структуры. Приведены результаты расчета коэффициентов передачи и отражения полосовых и режекторных фильтров, построенных на различных диэлектрических резонаторах в прямоугольном и круглом волноводах. Установлены наиболее оптимальные конфигурации, позволяющие достигать наилучших характеристик рассеяния., Розширена теорія розсіювання електромагнітних хвиль лінії передачи на системах зв'язаних діелектричних резонаторів різної форми та діелектричної проникності. Дано нове визначення коефіцієнтів зв'язку різних діелектричних резонаторів. Отримані аналітичні вирази для коефіцієнтів взаємного зв'язку діелектричних резонаторів циліндричної та сферичної форми, виконаних із різних матеріалів. Розглянуті основні закономірності зміни зв'язку при варіації параметрів структури. Приведені результати розрахунків коефіцієнтів передачи та відбиття смугових та режекторних фільтрів, побудованих на різних діелектричних резонаторах в прямокутному та круглому хвилеводах. Встановлено найбільш оптимальні конфігурації, які дозволяють досягати найкращих характеристик розсіювання.

Simple current- and voltage-controlled memristive circuit macro-models using SPICE are proposed to capture the nonlinear hysteresis loop behaviors in this paper. Different current-voltage characteristics are investigated by applying sinusoidal-wave, triangular-wave and square-wave source, respectively. Furthermore, using finite-difference time-domain (FDTD) emulator incorporated with a SPICE circuit solver, the current- or voltage-controlled memristive SPICE model is embedded into a planar microwave bandstop filter (BSF) and an ultra-wideband (UWB) monopole antenna, which connects two ends of the half-wavelength open-loop resonator and two sides of the U-slot in the radiating patch, respectively. The reconfigurability of the BSF and antenna notched band can be achieved by switching the states of the memristor.

Simple current- and voltage-controlled memristive circuit macro-models using SPICE are proposed to capture the nonlinear hysteresis loop behaviors in this paper. Different current-voltage characteristics are investigated by applying sinusoidal-wave, triangular-wave and square-wave source, respectively. Furthermore, using finite-difference time-domain (FDTD) emulator incorporated with a SPICE circuit solver, the current- or voltage-controlled memristive SPICE model is embedded into a planar microwave bandstop filter (BSF) and an ultra-wideband (UWB) monopole antenna, which connects two ends of the half-wavelength open-loop resonator and two sides of the U-slot in the radiating patch, respectively. The reconfigurability of the BSF and antenna notched band can be achieved by switching the states of the memristor.

Simple current- and voltage-controlled memristive circuit macro-models using SPICE are proposed to capture the nonlinear hysteresis loop behaviors in this paper. Different current-voltage characteristics are investigated by applying sinusoidal-wave, triangular-wave and square-wave source, respectively. Furthermore, using finite-difference time-domain (FDTD) emulator incorporated with a SPICE circuit solver, the current- or voltage-controlled memristive SPICE model is embedded into a planar microwave bandstop filter (BSF) and an ultra-wideband (UWB) monopole antenna, which connects two ends of the half-wavelength open-loop resonator and two sides of the U-slot in the radiating patch, respectively. The reconfigurability of the BSF and antenna notched band can be achieved by switching the states of the memristor.

A novel compact narrow-band bandstop filter is implemented by using the proposed spiral-shaped defected microstrip structure (SDMS) in this paper. Compared with other DMSs, the presented SDMS exhibits the advantage of compact size and narrow stopband. Meanwhile, an approximate design rule of the SDMS is achieved and the effects of the dimensions on the resonant frequency and 3 dB fractional bandwidth (FBW) are analyzed in detail. Both the simulation and measurement results of the fabricated bandstop filter show that it has a 10 dB stopband from 3.4 GHz to 3.6 GHz with more than 45 dB rejection at the center frequency.

A novel compact narrow-band bandstop filter is implemented by using the proposed spiral-shaped defected microstrip structure (SDMS) in this paper. Compared with other DMSs, the presented SDMS exhibits the advantage of compact size and narrow stopband. Meanwhile, an approximate design rule of the SDMS is achieved and the effects of the dimensions on the resonant frequency and 3 dB fractional bandwidth (FBW) are analyzed in detail. Both the simulation and measurement results of the fabricated bandstop filter show that it has a 10 dB stopband from 3.4 GHz to 3.6 GHz with more than 45 dB rejection at the center frequency.

The authors thank V. K. Velidi and S. Sanyal for their comments and careful attention to our paper, in which a wideband bandstop filter with four transmission zeros was presented. In these comments [1], the central point is their statement that equivalent stopband performances can be obtained with three and four transmission zeros. In general terms, we agree with most of the content of their comments and appreciate the contribution of their study. However, we would like to clarify some points. First of all, we can not agree with the comment "The authors considered the performance of filters having only even numbers of zeros." Although the implemented filter whose response is presented in [2] has four transmission zeros, the formulas included in our paper are also valid for a lower number of zeros.

The authors thank V. K. Velidi and S. Sanyal for their comments and careful attention to our paper, in which a wideband bandstop filter with four transmission zeros was presented. In these comments [1], the central point is their statement that equivalent stopband performances can be obtained with three and four transmission zeros. In general terms, we agree with most of the content of their comments and appreciate the contribution of their study. However, we would like to clarify some points. First of all, we can not agree with the comment "The authors considered the performance of filters having only even numbers of zeros." Although the implemented filter whose response is presented in [2] has four transmission zeros, the formulas included in our paper are also valid for a lower number of zeros.

In this paper, a new structure with only one (first order) bandstop is reported. A simple trapezoid shape of the microstrip line is introduced instead of the more complicated pattern. It obtains simple simulation, optimization and fabrication.

The shape of a popular split-ring defected ground structure (DGS) is modified by selecting different width of the sides with respect to microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. The unit cell is modeled by 3rd order elliptical lowpass filter and an equivalent circuit is presented accordingly. For proposed DGS, both pole and zero frequencies are obtained at lower values compared to split-ring DGS unit with uniform width. The variation of the width of the sides, parallel to microstrip line influences pole frequency. Two DGS cells with different pole frequencies cascaded under High-Low microstrip line realize a sharp and deep bandstop filter. Three-cascaded cells underneath a highlow impedance microstrip line produce sharper and wider bandstop filter characteristics.

The shape of a popular split-ring defected ground structure (DGS) is modified by selecting different width of the sides with respect to microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. The unit cell is modeled by 3rd order elliptical lowpass filter and an equivalent circuit is presented accordingly. For proposed DGS, both pole and zero frequencies are obtained at lower values compared to split-ring DGS unit with uniform width. The variation of the width of the sides, parallel to microstrip line influences pole frequency. Two DGS cells with different pole frequencies cascaded under High-Low microstrip line realize a sharp and deep bandstop filter. Three-cascaded cells underneath a highlow impedance microstrip line produce sharper and wider bandstop filter characteristics.

The shape of a popular split-ring defected ground structure (DGS) is modified by selecting different width of the sides with respect to microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. The unit cell is modeled by 3rd order elliptical lowpass filter and an equivalent circuit is presented accordingly. For proposed DGS, both pole and zero frequencies are obtained at lower values compared to split-ring DGS unit with uniform width. The variation of the width of the sides, parallel to microstrip line influences pole frequency. Two DGS cells with different pole frequencies cascaded under High-Low microstrip line realize a sharp and deep bandstop filter. Three-cascaded cells underneath a highlow impedance microstrip line produce sharper and wider bandstop filter characteristics.

The shape of a popular split-ring defected ground structure (DGS) is modified by selecting different width of the sides with respect to microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. The unit cell is modeled by 3rd order elliptical lowpass filter and an equivalent circuit is presented accordingly. For proposed DGS, both pole and zero frequencies are obtained at lower values compared to split-ring DGS unit with uniform width. The variation of the width of the sides, parallel to microstrip line influences pole frequency. Two DGS cells with different pole frequencies cascaded under High-Low microstrip line realize a sharp and deep bandstop filter. Three-cascaded cells underneath a highlow impedance microstrip line produce sharper and wider bandstop filter characteristics.

The shape of a popular split-ring defected ground structure (DGS) is modified by selecting different width of the sides with respect to microstrip line. The frequency characteristics of proposed DGS unit show an attenuation zero close to the attenuation pole frequency. The unit cell is modeled by 3rd order elliptical lowpass filter and an equivalent circuit is presented accordingly. For proposed DGS, both pole and zero frequencies are obtained at lower values compared to split-ring DGS unit with uniform width. The variation of the width of the sides, parallel to microstrip line influences pole frequency. Two DGS cells with different pole frequencies cascaded under High-Low microstrip line realize a sharp and deep bandstop filter. Three-cascaded cells underneath a highlow impedance microstrip line produce sharper and wider bandstop filter characteristics.

In this paper, a new structure with only one (first order) bandstop is reported. A simple trapezoid shape of the microstrip line is introduced instead of the more complicated pattern. It obtains simple simulation, optimization and fabrication.

In this article, a second-order dual-band bandpass filter is designed. The filter consists of two dual-band resonators connected by a dual-band admittance inverter. The dual-band resonator unit is made of two shunt stubs that coordinately produce two resonances. A novel dual-band quarter-wavelength line acts as the admittance inverter, providing suitable admittance transformations. To verify the design concept, a filter working at 2 and 5 GHz is devised and fabricated on Rogers' RO3006 printed circuit boards. In addition, the dual-band filter is connected with a bandstop filter to suppress the unwanted spurious response. (C) 2008 Wiley Periodicals, Inc.

In this article, a second-order dual-band bandpass filter is designed. The filter consists of two dual-band resonators connected by a dual-band admittance inverter. The dual-band resonator unit is made of two shunt stubs that coordinately produce two resonances. A novel dual-band quarter-wavelength line acts as the admittance inverter, providing suitable admittance transformations. To verify the design concept, a filter working at 2 and 5 GHz is devised and fabricated on Rogers' RO3006 printed circuit boards. In addition, the dual-band filter is connected with a bandstop filter to suppress the unwanted spurious response. (C) 2008 Wiley Periodicals, Inc.

In this article, a second-order dual-band bandpass filter is designed. The filter consists of two dual-band resonators connected by a dual-band admittance inverter. The dual-band resonator unit is made of two shunt stubs that coordinately produce two resonances. A novel dual-band quarter-wavelength line acts as the admittance inverter, providing suitable admittance transformations. To verify the design concept, a filter working at 2 and 5 GHz is devised and fabricated on Rogers' RO3006 printed circuit boards. In addition, the dual-band filter is connected with a bandstop filter to suppress the unwanted spurious response. (C) 2008 Wiley Periodicals, Inc.