Showing papers in "Frequenz in 2018"
TL;DR: In this article, a compact 4×4 multiple-input-multiple-output (MIMO) patch antenna has been presented for triple band operation, where four complementary split-ring resonators have been etched in the ground plane exactly below the four patch antennas for attaining compactness.
Abstract: Abstract In this paper, a compact 4×4 multiple-input-multiple-output (MIMO) patch antenna has been presented for triple band operation. Out of the 4 antennas, two are tuned to cover DCS (Digital Cellular System) downlink and two are tuned to cover DCS uplink frequency separately along with two common operating frequency centered around 2.45 GHz and 875 MHz. Four complementary split-ring resonators (CSRRs) have been etched in the ground plane exactly below the four patch antennas for attaining compactness from 0.36λ02 to 0.13λ02. In addition to this, by optimizing CSRRs outer radius, one lower common band operation of around 875 MHz (0.031λ02) has been obtained. Two, square split-ring resonators (SRRs) are placed between patch antennas to increase isolation by almost 7 dB around DCS band. The proposed MIMO antenna has been fabricated on an FR4 substrate (60×60×0.8) mm3 with dielectric constant, εr=4.3 having an antenna area of 0.13λ02. The Proposed MIMO antenna has two common operating bands, 850–900 MHz, 2410–2466 MHz and one individual band from 1725–1770 MHz for one group of two antennas of dimensions 17×22 mm2 and another individual band from 1800–1845 MHz for another group of two antennas of dimensions 17×23 mm2, where reflection coefficient is less than −10 dB with a minimum isolation of 17 dB. Diversity performance of the proposed MIMO antenna has been verified experimentally on all three bands. However, there is a slight deviation in the DCS operating band due to two different groups of antennas.
32 citations
TL;DR: In this paper, the H $H$-polarized electromagnetic wave by planar graphene grating in the THz range is considered and the scattering and absorption characteristics are studied.
Abstract: Abstract Diffraction of the H $H$- polarized electromagnetic wave by the planar graphene grating in the THz range is considered. The scattering and absorption characteristics are studied. The scattered field is represented in the spectral domain via unknown spectral function. The mathematical model is based on the graphene surface impedance and the method of singular integral equations. The numerical solution is obtained by the Nystrom-type method of discrete singularities.
32 citations
TL;DR: In this article, an 8-channel optical demultiplexer based on photonic crystal ring resonator was proposed for wavelength division multiplexing (WDM) applications.
Abstract: Abstract Transmission efficiency, quality factor, crosstalk levels and number of output channels are the most crucial parameters in designing optical demultiplexers, suitable for wavelength division multiplexing applications. In this paper we proposed an 8-channel optical demultiplexer based on photonic crystal ring resonator. For performing wavelength selection task we used eight ring resonators. The resonance wavelength of the ring resonators depends on the dimensions of the ring core, therefore we choose eight different values for the lattice constant of the ring resonators core section. The average channel spacing of the structure is about 3 nm the transmission efficiency in most of the channels is equal or more than 99 % except in one channels whose transmission efficiency is 85 %.
14 citations
TL;DR: In this paper, a 1 to 8 demultiplexer based on Photonic crystal (PhC) was designed and simulated to give low crosstalk between outputs.
Abstract: Abstract In this paper we are going to design and simulating a 1 to 8 demultiplexer based on Photonic Crystal (PhC) that where in wavelengths was guided to her coupled cavity and after that our Intended output. This structure is good Selection to communication operations that their wavelengths are around 1550nm. High Q factor, high transmission speed and low crosstalk between wavelengths are the advantages of this structure. The area of this structure is 560μm2 $560\\,{\\rm{ \\mu }}{{\\rm{m}}^{\\rm{2}}}$. The wavelengths was selected to this work are 1602.1 nm, 1598.3 nm, 1595.2 nm, 1591.8 nm, 1588.6 nm, 1585.4 nm, 1582.4 nm, 1579.6 nm. In this paper we are going to prepare the crosstalk between outputs and our main goal is giving low crosstalk between outputs.
14 citations
TL;DR: A lumped element model of RF MEMS capacitive switches which is scalable with the lateral dimensions of the bridge is proposed by using one or more artificial neural networks to model the relationship between the bridge dimensions and the inductive and resistive elements of the model.
Abstract: Abstract In this paper a lumped element model of RF MEMS capacitive switches which is scalable with the lateral dimensions of the bridge is proposed. The dependence of the elements of the model on the bridge dimensions is introduced by using one or more artificial neural networks to model the relationship between the bridge dimensions and the inductive and resistive elements of the lumped element model. The achieved results show that the developed models have a good accuracy over the whole considered range of the bridge dimension values.
13 citations
TL;DR: In this paper, a shrunken Wilkinson power divider with harmonic suppression, using two identical resonators in the conventional Wilkinson Power divider, is designed, and a microstrip implementation of this design operating at 1 GHz with the second to eighth harmonic suppression is developed.
Abstract: Abstract A novel scheme of a shrunken Wilkinson power divider with harmonic suppression, using two identical resonators in the conventional Wilkinson power divider is designed. Moreover, the LC equivalent circuit and its relevant formulas are provided. To substantiate the functionality and soundness of design, a microstrip implementation of this design operating at 1 GHz with the second to eighth harmonic suppression, is developed. The proposed circuit is relatively smaller than the conventional circuit, (roughly 55% of the conventional circuit). Simulation and measurement results for the proposed scheme, which are highly consistent with one another, indicate a good insertion loss about 3.1 dB, input return loss of 20 dB and isolation of 20 dB, while sustaining high-power handling capability over the Wilkinson power divider.
13 citations
TL;DR: In this paper, a low profile wide slot antenna for dual band and dual sense circular polarization (CP) is proposed and is simulated by using HFSS simulation software and a close agreement has been found between the simulated and the measured results.
Abstract: Abstract A low profile wide slot antenna for dual band and dual sense circular polarization (CP) is proposed here and is simulated by using HFSS simulation software.The proposed antenna having a C shaped patch for dual band operation and a wide square slot etched on the ground with two strips for CP operation. In between radiating patch and ground plane, designed antenna has a layer of easily available dielectric (FR-4) material. Proposed antenna shows an impedance bandwidth of 13.8 % at 2.38 GHz of centre frequency and 9.7 % at 4.43 GHz of centre frequency for lower and upper band respectively. The 3-dB axial ratio (AR) bandwidths for lower and upper band are 18.8 % (at 2.44 GHz of centre frequency) and 13.3 % (at 4.29 GHz of centre frequency), respectively. The peak gain for the lower and upper band is found as 4.1 dBi and 3.3 dBi, respectively. A close agreement has been found between the simulated and the measured results.
12 citations
TL;DR: In this paper, a four port MIMO antenna with polarization diversity for ultrawideband (UWB) application is proposed, where the antenna contains four monopoles where each monopole has three concentric rings.
Abstract: Abstract A compact four port multiple-input-multiple-output (MIMO) antenna with polarization diversity for ultrawideband (UWB) application is proposed. The antenna contains four monopoles where each monopole has three concentric rings. Orthogonal arrangement of monopoles of the antenna provides good isolation and polarization diversity. The antenna has compact size of 36×36×1.6 mm3. It operates in the frequency band of 3.2 to 11 GHz where isolation is better than 15 dB. The envelop correlation coefficient (ECC) and diversity gain from S-parameter have been calculated to evaluate MIMO performance of the antenna. In addition to ensure distortion less transmission in UWB group delay is also calculated.
11 citations
TL;DR: In this paper, a pair of dual-band closely spaced MIMO monopole antenna array working at WLAN 2.45/5.25GHz with a dualband coupled resonator structure for decoupling is proposed.
Abstract: Abstract A pair of dual-band closely spaced MIMO monopole antenna array working at WLAN 2.45/5.25GHz with a dual-band coupled resonator structure for decoupling is proposed, the edge-to-edge distance of which is 0.0735λ0 ${^{\lambda _0}}$ at 2.45GHz and 0.1575λ0 ${^{\lambda _0}}$ at 5.25GHz. Simulation and measurement on coupled antennas and decoupled antennas indicate that mutual coupling reductions of 24.52dB and 26.57dB at two frequencies are achieved. With good impedance matching, improved total efficiency and increased channel capacity, the proposed structure owns good applicability, compact size and effective decoupling capability, and is promising in the application of wireless terminal MIMO system.
10 citations
TL;DR: In this paper, a compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole antenna using embedded E-shaped structure with wireless local area network (WLAN) band-rejection is presented.
Abstract: Abstract A compact coplanar waveguide (CPW)-fed ultra-wideband (UWB) monopole antenna using embedded E-shaped structure with wireless local area network (WLAN) band-rejection is presented. The introduction of this E-shaped structure working as the radiator can enhance the impedance bandwidth of the UWB antenna without increasing the overall size. For preventing the interference from WLAN system, a pair of L-shaped stubs are connected to the ground of UWB antenna to create the rejected band. The center frequency of this rejected band is about 5.5 GHz with the rejection range of 5.2~5.8 GHz. Good agreement can be observed between the simulated and measured results.
9 citations
TL;DR: In this article, a 4-port ultra-wide band (UWB) multiple-input-multiple-output (MIMO) slot antenna with dual polarization is presented.
Abstract: Abstract A compact 4-port ultra-wide band (UWB) multiple-input-multiple-output (MIMO) slot antenna with dual polarization is presented. The key features of antenna are: has directive radiation in two planes and low correlation without use of additional decoupling structure. The antenna contains four microstrip feedlines having circular patches backed by stepped circular slots. Orthogonal arrangement of each slot antenna increases compactness with polarization diversity and good isolation. The antenna has compact size of 36×36×0.8 mm3. It operates in the frequency band of 3.1 to 11.9 GHz and isolation is better than 15 dB. The superior diversity performance is ensured by calculating envelope correlation coefficient (ECC) and diversity gain. In addition to guarantee distortion less transmission in UWB group delay is also measured.
TL;DR: In this paper, a design with wideband and circularly polarized radiation antenna from an open-slot antenna has been demonstrated, which consists of an open slot and an inverted-L strip feeding, providing a large bandwidth, which completely cover the Wimax (3.3-3.8 GHz) and WLAN (2.4-2.48 GHz) bands.
Abstract: Abstract A design with wideband and circularly polarized radiation antenna from an open-slot antenna has been demonstrated in this paper. The proposed antenna, which consists of an open slot and an inverted-L strip feeding, provides a large bandwidth, which completely cover the Wimax (3.3–3.8 GHz) and WLAN (2.4–2.48 GHz) bands. The open slot is formed by an modified ground plane with a slit cut and monofilar spiral stubs employed, which fed by an asymmetrical inverted-L strip feedline using a via. As demonstrated, the CP operation was significantly improved by loading monofilar spiral stubs connected to the asymmetric feedline by means of a via. A parametric study of the key parameters is made and the mechanism for circular polarization is described. After optimization, the impedance bandwidth is approximately 3.78 GHz (2.12 to 5.9 GHz) and the 3 dB axial ratio bandwidth is approximately 2.75 GHz (2.2 to 4.95 GHz), which represent fractional bandwidths of approximately 94.3 % and 76.9 %, respectively.
TL;DR: In this paper, a miniaturized Band Pass Filter (BPF) with wide stopband centered at 0.350 GHz for TETRA band applications is proposed using a Spiral Short Circuit quarter wavelength Stepped Impedance Resonator (SSC-SIR) and a stub loaded on feed line for enhancement of rejection level in the stopband.
Abstract: Abstract In this letter, a miniaturized Band Pass Filter (BPF) with wide stopband centered at 0.350 GHz for TETRA band applications is proposed using a Spiral Short Circuit quarter wavelength Stepped Impedance Resonator (SSC-SIR) and a stub loaded on feed line for enhancement of rejection level in the stopband. Spiral configuration of the resonator is used for the miniaturization of BPF. The proposed BPF provides a 3dB fractional bandwidth of 13.7 % with two transmission zeros in the lower and upper stopband to provide good selectivity and four transmission zeros which provide wide stopband upto 6.86f0. Proposed BPF has a very compact size of 0.064λg×0.062λg.
TL;DR: In this article, an ultra wideband bandpass filter with ultra wide stopband based on a rectangular ring resonator is presented for the operational frequency band from 4.10 GHz to 10.80 GHz with an ultra-wide stopband from 11.23 GHz to 40 GHz.
Abstract: Abstract An ultra-wideband (UWB) bandpass filter with ultra-wide stopband based on a rectangular ring resonator is presented. The filter is designed for the operational frequency band from 4.10 GHz to 10.80 GHz with an ultra-wide stopband from 11.23 GHz to 40 GHz. The even and odd equivalent circuits are used to achieve a suitable analysis of the proposed filter performance. To verify the design and analysis, the proposed bandpass filter is simulated using full-wave EM simulator Advanced Design System and fabricated on a 20mil thick Rogers_RO4003 substrate with relative permittivity of 3.38 and a loss tangent of 0.0021. The proposed filter behavior is investigated and simulation results are in good agreement with measurement results.
TL;DR: In this article, a triple band rejection was produced by inserting the complementary co-directional split-Ring Resonator (CC.SRR) on the radiating element for WiMAX/WLAN (3.4-3.95 GHz/5.35-5.9 GHz) and E-band satellite communications (6.7-7.7 GHz).
Abstract: Abstract In this paper, a compact ultra-wideband (UWB) monopole antenna with triple band-notched characteristics is presented. These triple band rejections are produced by inserting the Complementary Co-directional Split-Ring Resonator (CC.SRR) on the radiating element for WiMAX/WLAN (3.4–3.95 GHz/5.35–5.9 GHz) and Electromagnetic Band Gap (EBG) structure in the vicinity of transmission line for X-band satellite communications (6.7–7.7 GHz). The proposed antenna with a total size of 18×20.9×1.63 mm3 has been constructed and tested. An equivalent RLC circuit model is proposed and investigated. The simulated and measured results show that the proposed antenna has an impedance bandwidth (VSWR<2) extanding from 3.05 GHz to 14 GHz with triple notched bands of [3.3–3.9 GHz], [5.25–5.86 GHz] and [6.7–7.7 GHz]. The triple band notched characteristics and the good radiation patterns make the proposed antenna a good candidate for the UWB applications.
TL;DR: In this paper, various shapes of DR antennas excited by common feed have been proposed and successfully implemented for wideband applications, while common excited feed is inverted trapezoidal conformal patch.
Abstract: Abstract In this paper various shapes of DR antennas excited by common feed have been proposed and successfully implemented for wideband applications. Proposed structures are Hemispherical, Arrow-shaped and Triangular DRA, while common excited feed is inverted trapezoidal conformal patch. These shapes of DR offer significant optimization in several parameters such as impedance bandwidth, peak gain and bandwidth per unit volume of the antenna. By using inverted trapezoidal patch feed mechanism an impedance bandwidth (VSWR<2) of about 63 % for hemispherical shape, 66 % for arrow shape, and 72 % for triangular shape DRA has been achieved with maximum bandwidth per unit volume. Proposed wideband DRAs i. e. triangular, hemispherical, and arrow shapes of DR antennas cover almost complete C-band (4 GHz–8 GHz) frequency spectrum of microwave. The average peak gain within the operating band for hemispherical, arrow, and triangular shape DRA are about 5, 5.4, and 5.5 dB respectively. A comparative analysis of proposed structures for various antenna parameters has been analyzed by HFSS (High-Frequency Structure Simulator) and validated by experimental results.
TL;DR: In this paper, a Terahertz protein sensing concept based on subwavelength Ge resonators is presented and characterized with a resonance frequency of 0.5 THz and calculated local intensity enhancement of 10.000.
Abstract: Abstract A Terahertz protein sensing concept based on subwavelength Ge resonators is presented. Ge bowtie resonators, compatible with CMOS fabrication technology, have been designed and characterized with a resonance frequency of 0.5 THz and calculated local intensity enhancement of 10.000. Selective biofunctionalization of Ge resonators on Si wafer was achieved in one step using lipoic acid-HaloTag ligand (LA-HTL) for biofunctionalization and passivation. The results lay the foundation for future investigation of protein tertiary structure and the dynamics of protein hydration shell in response to protein conformation changes.
TL;DR: In this paper, a miniaturized dual-band FSS with closely spaced resonances is proposed, where the frequency ratio of upper to lower resonant frequency is 1.27 and the size of the proposed FSS is only 0.057λ0.
Abstract: Abstract Using 2.5-dimension structure, a novel miniaturized dual-band FSS with closely spaced resonances is proposed in the paper. The special design of the geometry contributes to two closely spaced resonances at 1.69 GHz and 2.16 GHz respectively and the frequency ratio of upper to the lower resonant frequency is 1.27. Besides, the two bands can be controlled individually by varying corresponding parameters. The size of the proposed FSS is only 0.057λ0, where the λ0 represents free space wavelength at lower resonant band. Furthermore, the simulation results show the proposed FSS exhibits stable response with different incident angles and polarizations. To understand the design better, the distribution of surface current is analyzed to explain the operating mechanism of the proposed FSS. Finally, the proposed FSS is fabricated and the measurement results are in accordance with the simulation results.
TL;DR: This study presents the advances in the development of a silicon-based THz sub-wavelength imager usable in life science applications, especially for tumour margin identification.
Abstract: Abstract Breast Cancer is one of the most frequently diagnosed cancer diseases worldwide, and the most common invasive tumour for women. As with all cancers, early detection plays a major role in reducing the mortality and morbidity rate. Currently, most breast cancers are detected due to clinical symptoms, or by screening mammography. The limitations of these techniques have resulted in research of alternative methods for imaging and detecting breast cancer. Apart from this, it is essential to define precise tumour margins during breast-conserving surgeries to reduce the re-excision rate. This study presents the advances in the development of a silicon-based THz sub-wavelength imager usable in life science applications, especially for tumour margin identification.
TL;DR: In this paper, the authors presented a single-band system for gas spectroscopy based on integrated transmitters and receivers fabricated in IHPs 0.13 um SiGe BiCMOS technology.
Abstract: Breath gas analysis is a promising non-invasive tool for medical diagnosis as there are thousands of Volatile Organic Compounds (VOCs) in human breath that can be used as health monitoring markers. Millimeter-wave/terahertz molecular spectroscopy is highly suitable for breath gas analysis due to unique fingerprint spectra of many VOCs in that frequency range. We present our recent work on sensor systems for gas spectroscopy based on integrated transmitters (TX) and receivers (RX) fabricated in IHPs 0.13 um SiGe BiCMOS technology. For a single-band system, spectroscopic measurements and beam profiles are presented. The frequency is tuned by direct voltage-frequency tuning and by a fractional-n PLL, respectively. The spectroscopic system includes a folded gas absorption cell with gas pre-concentration abilities demonstrating the detection of a 50 ppm mixture of ethanol in ambient air corresponding to a minimum detectable concentration of 260 ppb. Finally, the design of a 3-band system covering frequencies from 225 to 273 GHz is introduced.
TL;DR: In this article, a broad overview of current methods for the identification and quantification of the human dehydration level is given, starting from most common clinical setups, including vital parameters and general patients' appearance, more quantifiable results from chemical laboratory and electromagnetic measurement methods are reviewed.
Abstract: Abstract The aim of this article is to give a broad overview of current methods for the identification and quantification of the human dehydration level. Starting off from most common clinical setups, including vital parameters and general patients’ appearance, more quantifiable results from chemical laboratory and electromagnetic measurement methods will be reviewed. Different analysis methods throughout the electromagnetic spectrum, ranging from direct current (DC) conductivity measurements up to neutron activation analysis (NAA), are discussed on the base of published results. Finally, promising technologies, which allow for an integration of a dehydration assessment system in a compact and portable way, will be spotted.
TL;DR: Ex-vivo burned porcine skin is utilized to visualize and quantify skin that has been burned in different ways, and to access its effect on millimeter-wave images.
Abstract: Abstract Millimeter-wave imaging is a promising technology for diagnosing skin burns, that may make it easier to assess and determine the burn depth in the near future. However, up to now, it has not yet been brought to clinical use due to the lack of clinical trails on patients and a millimeter-wave-aided classification of skin burns. In this paper, in a preliminary step, ex-vivo burned porcine skin is utilized to visualize and quantify skin that has been burned in different ways, and to access its effect on millimeter-wave images. For the first time, a 24 hour study of in-vivo human skin visualizes the effect of wound dressings using a fast imaging system operating at frequencies from 70 to 80 GHz. For validation, the effective relative permittivity of the skin and the dressings are measured using a open-ended coaxial probe. An analytical model is applied to calculate the reflection coefficient which are compared to the intensity of the millimeter-wave images to validate the model.
TL;DR: In this paper, a hexagonal fractal patch antenna with Koch snowflake fractal at its edges has been proposed for ultra wideband (UWB) applications and measured results show that the measured radiation patterns of this antenna are nearly omnidirectional in H-plane and bidirectional on E-plane.
Abstract: Abstract This paper presents the design, fabrication, and measurement of a novel ultra-wideband (UWB) hexagonal fractal patch antenna. This antenna uses hexagonal shape with Koch snowflake fractal at its edges. The proposed antenna has been excited using microstrip feed. The measured result of this antenna offers the ultra wideband characteristics from 3.265 GHz to 8.2 GHz. The antenna is practically fabricated and tested. Measured results show a good agreement with simulated results. The measured radiation patterns of this antenna are nearly omnidirectional in H-plane and bidirectional in E-plane. This antenna holds applications in many satellite communication transmissions, some Wi-Fi devices, cordless telephones, and weather radar systems. In this paper, an approach for multi-band antennas is proposed. First, a hexagonal patch is taken, it is fractured using Koch structure. The antenna shows compact dimensions with good S11 and pattern performance to be adopted for UWB applications.
TL;DR: The signal-to-noise ratio as the most important quality measure used in communications, control or measurement technology is accurately introduced and the transmission of quadrature amplitude modulated signals over additive WGN channels together with the optimum maximum likelihood (ML) detector is considered in a demonstrative and intuitive way.
Abstract: Abstract This paper assembles some information about white Gaussian noise (WGN) and its applications. It starts from a description of thermal noise, i. e. the irregular motion of free charge carriers in electronic devices. In a second step, mathematical models of WGN processes and their most important parameters, especially autocorrelation functions and power spectrum densities, are introduced. In order to proceed from mathematical models to simulations, we discuss the generation of normally distributed random numbers. The signal-to-noise ratio as the most important quality measure used in communications, control or measurement technology is accurately introduced. As a practical application of WGN, the transmission of quadrature amplitude modulated (QAM) signals over additive WGN channels together with the optimum maximum likelihood (ML) detector is considered in a demonstrative and intuitive way.
TL;DR: In this paper, a method for retrieving the soil moisture based on RADARSAT-2 SAR scattering data and Terra MODIS surface reflectance data was proposed, which can effectively decouple the impact of surface vegetation and roughness on radar backscattering coefficient, when the volume scattering is not dominant.
Abstract: Abstract Changes in the soil moisture are a key factor in the deterioration of the ecological environment caused by mining geological disasters. In this study, which presents a case study of the arid and semi-arid aeolian sand mining area along the Inner Mongolia-Shaanxi Province boundary, a method for retrieving the soil moisture based on RADARSAT-2 SAR scattering data and Terra MODIS surface reflectance data was proposed. The retrieval of RADARSAT-2 mainly used the Alpha approximation model based on the change detection technique, a model proposed by Balenzano et al., which can effectively decouple the impact of surface vegetation and roughness on radar backscattering coefficient, when the volume scattering is not dominant. Using 12 periods of RADARSAT-2 HH polarization data in conjunction with the Alpha approximation model, a matrix equation was constructed, which contains 11 equations and 12 unknowns. To solve this underdetermined system, a bounded linear least-squares optimization was adopted. Once the unknowns were determined, the relative dielectric constant could be analytically derived and then the soil moisture could be estimated by using the dielectric mixing model and compared with the MODIS retrieval results based on the spatial feature method. Finally, the DInSAR results of RADARSAT-2 were used to investigate the effects of high-intensity underground mining activities on the surface soil moisture. The study found that the RADARSAT-2 soil moisture estimates demonstrated good consistency with the MODIS retrieval results. Among four comparison groups, the maximum correlation coefficient was 0.599, and the highest proportion of sampling points for which the absolute error was less than 3 % was 55.6 %. The absolute error of all of the sampling points did not exceed 10 %, which demonstrates the reliability of the RADARSAT-2 retrieval results. A comparison among the 72 soil moisture values from six mining subsidence areas and corresponding non-subsidence areas in the study area in 2012 showed that 38 soil moisture values from the non-subsidence areas were higher than those from the subsidence areas. These values accounted for 53 % of the total, indicating that high-intensity mining activities have a certain negative impact on the surface soil moisture, although this impact is slightly insignificant.
TL;DR: In this article, a dual-mode microwave applicator for diagnosis and thermal ablation treatment of tumorous tissue is presented, which is realized by integrating a planar resonator array to detect abnormalities by a relative dielectric analysis, and secondly, perform a highly localized thermal ablating.
Abstract: Abstract The concept of a novel dual-mode microwave applicator for diagnosis and thermal ablation treatment of tumorous tissue is presented in this paper. This approach is realized by integrating a planar resonator array to, firstly, detect abnormalities by a relative dielectric analysis, and secondly, perform a highly localized thermal ablation. A further essential advantage is addressed by designing the applicator to be MRI compatible to provide a multimodal imaging procedure. Investigations for an appropriate frequency range lead to the use of much higher operating frequencies between 5 GHz and 10 GHz, providing a significantly lower power consumption for microwave ablation of only 20 W compared to commercial available applicators.
TL;DR: In this paper, a S-band 8-element cylindrical conformal array was designed and a 16-element CCA was constructed and tested at two different steering angles to optimize the pulse durations and the switch-on instants of the time-modulated elements.
Abstract: Abstract By virtue of the excellent aerodynamic performances, conformal phased arrays have been attracting considerable attention. However, for the synthesis of patterns with low/ultra-low sidelobes of the conventional conformal arrays, the obtained dynamic range ratios of amplitude excitations could be quite high, which results in stringent requirements on various error tolerances for practical implementation. Time-modulated array (TMA) has the advantages of low sidelobe and reduced dynamic range ratio requirement of amplitude excitations. This paper takes full advantages of conformal antenna arrays and time-modulated arrays. The active-element-pattern, including element mutual coupling and platform effects, is employed in the whole design process. To optimize the pulse durations and the switch-on instants of the time-modulated elements, multiobjective invasive weed optimization (MOIWO) algorithm based on the nondominated sorting of the solutions is proposed. A S-band 8-element cylindrical conformal array is designed and a S-band 16-element cylindrical-parabolic conformal array is constructed and tested at two different steering angles.
TL;DR: In this paper, a triple-band bow-tie dipole antenna with three bent dipoles with different lengths which correspond to different operating frequencies is presented, which is suitable for WLAN/WiMAX/LTE applications.
Abstract: Abstract In this paper, a novel triple-band dipole antenna is presented. The proposed antenna has a very simple structure and is easily designed. The idea of the antenna is based on the traditional wideband bow-tie dipole antenna. Via etching slots on the bow-tie patch, three bent dipoles with different lengths which correspond to different operating frequencies are formed. Hence, the triple-band antenna is generated. Each operating frequency band realizes wideband and can be adjusted almost independently. And the antenna is fed by a 50 Ω microstrip line and a wideband microtrip-to-coplanar-stripline (CPS) transition as a balun. The good performances of the proposed antenna are achieved by a mass of simulations and measurements. The measured results have a good agreement with the simulated ones. The results show that the proposed antenna obtains three bandwidths at 2.38~2.65 GHz (10.7 %), 3.17~4.08 GHz (25.1 %), and 4.75~6.00 GHz (23.2 %) with the reflection coefficient less than −10 dB. In addition, the stable gain and quasi-omnidirectional radiation patterns are obtained in the operating frequency bands. Therefore, the proposed antenna is suitable for WLAN/WiMAX/LTE applications.
TL;DR: In this paper, a varactor-loaded half-mode substrate integrated waveguide (HMSIW) reconfigurable bandpass filter (BPF) is proposed, which is composed of complementary split-ring resonators (CSRRs) and varactors.
Abstract: Abstract A varactor-loaded half-mode substrate integrated waveguide (HMSIW) reconfigurable bandpass filter (BPF) is proposed in this paper. The proposed BPF is composed of complementary split-ring resonators (CSRRs) and varactors. Meanwhile, a nonmetalized via is employed in the center of the CSRR. It is noted that the varactor is embedded into the nonmetalized via, which can significantly reduce the tunable filter size. By changing the reverse bias voltage of the varactor, the resonant frequency of the proposed filter can be adjusted. Moreover, low insert loss (IL) and wide tuning range can be achieved. In order to validate its practicability, a BPF with the frequency ranging from 1.9 GHz to 2.5 GHz is fabricated and good agreement between the simulated and measured results is observed.
TL;DR: In this paper, a novel Tetracuspid-shaped dielectric resonator antenna (DRA) mounted with conical horn is presented and investigated for broadband applications, which achieves a broadband impedance bandwidth of 70.9% for |S11| < 10 dB, ranging from 2 GHz to 4.2 dB.
Abstract: Abstract A novel Tetracuspid-shaped dielectric resonator antenna (DRA) mounted with conical horn is presented and investigated for broadband applications. The dielectric used for investigation is a ceramic composite material having a dielectric constant ( εr$\\varepsilon_r$) of 12.9. Tetracuspid-shaped resonator geometry achieves a broadband impedance bandwidth of 70.9 % for |S11|<‒10 dB, ranging from 2 GHz to 4.2 GHz. Tetracuspid-shaped reduces the DRA volume by 78 % (without horn) as compared to conventional cylindrical DRA; with reduced volume of 14.4 cm3 which diminishes the cost and weight. Gain of proposed antenna is further enhanced up to 9.5 dBi in operating band by mounting a conical horn. Achieved average peak gain is ~7 dBi. Proposed antenna covers bands of different wireless communication systems like Wi-Max and WLAN (2.4 GHz, 2.5 GHz, 3.3 GHz and 3.5 GHz). The simulated results are validated by experimentally measured outcomes and these are well in agreement.