Showing papers on "Stub (electronics) published in 2015"

Wideband rectenna and rectifying apparatus for rectenna

Abstract: A rectenna according to the present invention includes a circular-polarized patch antenna having dual slots fed by a microstrip and configured to receive and output a radio frequency (RF) signal, and a rectifying circuit configured to convert for output the RF signal, received by the circular-polarized patch antenna, into a direct current (DC) signal and transfer the DC signal from the antenna to a load, wherein the rectifying circuit comprises at least one radial stub.

Enhanced Figure of Merit in Fano Resonance-Based Plasmonic Refractive Index Sensor

Abstract: Surface plasmon (SP) modes possesses an intriguing feature of confining light beyond diffraction limit, which makes it very attractive for sensing applications Here, we theoretically investigated an ultra compact SP sensor using metal–insulator–metal (MIM) waveguide geometry MIM waveguide is coupled to a pair of stub resonators and both the stub resonators are loaded with a metallic nanoslit of silver The stubs and the MIM waveguide are filled with liquid/gaseous material which is to be sensed The Fano resonance, which is very sensitive to any change in refractive index of the material, is excited in the structure by breaking marginal symmetry The structure is numerically simulated by the finite difference time-domain method (FDTD), and the result shows that the resonance wavelength has a linear relation with refractive index of the material under sensing In the optimum design of the proposed sensor, the maximum sensitivity is obtained as high as $S= 1060$ nm/refractive index unit with a large value of figure of merit (FOM = 1767) and an ultra narrow linewidth $\Delta \lambda =6$ nm Thus, the device is well suited for designing on-chip optical sensors

Wideband Stub-Loaded Slotline Antennas Under Multi-Mode Resonance Operation

Abstract: A novel center-fed wideband slotline antenna is proposed using the multi-mode resonance concept. By symmetrically introducing one or two pairs of slot stubs along the slotline resonator near the nulls of electric field distribution of the second odd-order mode, two modes are excited in a single slotline radiator. With the help of these stubs, the second odd-order mode can be gradually merged with its first counterpart, resulting in a wideband radiation characteristic with two resonances. Prototype antennas are then designed and fabricated to experimentally validate the principle and design approach. It is shown that the operation fractional bandwidth of the proposed slotline antenna could be effectively increased to 31.5% while keeping an inherent narrow slot structure.

Compact Balanced Dual- and Tri-band Bandpass Filters Based on Stub Loaded Resonators

Abstract: A stub loaded resonator (SLR) is presented in this letter, which can achieve dual-band or tri-band differential-mode (DM) bandpass response with a high common-mode (CM) suppression. By changing the length of the center-loaded stub, the resonant frequency of the CM can be varied without affecting that of the DM. This helps in simplifying the design and tuning processes of the balanced filters. In order to validate its practicalbility, two balanced bandpass filters (BPFs) with two and three DM passbands and good CM suppression are designed. Good agreement between simulated and measured results is observed. To our best knowledge, the proposed balanced tri-band BPF is the first ever reported.

A Refractive Index Nanosensor Based on Fano Resonance in the Plasmonic Waveguide System

Abstract: A novel and compact refractive index sensor based on Fano resonance in the plasmonic waveguide system, which comprises with a stub and groove resonator coupled with a metal–insulator–metal waveguide, is proposed and investigated by the finite-element method. Due to the interaction of the narrow discrete resonance and a broad spectrum caused by the stub resonator and the groove, respectively, the transmission spectrum exhibits a sharp asymmetrical profile. Simulation results show that the Fano resonance can be easily tuned by changing the parameters of the structure. These characteristics offer flexibility to design the devices. This nanosensor yields a sensitivity of $\sim 1260$ nm/RIU and a figure of merit of $\sim 2.3\,\times \, 10^{\mathrm {\mathbf {4}}}$ . This letter is significant for design and application of the sensitive nanoscale refractive index sensor.

Novel Design of Compact UWB Dielectric Resonator Antenna With Dual-Band-Rejection Characteristics for WiMAX/WLAN Bands

Abstract: A novel compact dual band-notched dielectric resonator antenna (DRA) for ultrawideband (UWB) applications is proposed Here, the bandwidth enhancement and the first band notch is realized by embedding a stub that is located to the hollow center of a U-shaped feedline simultaneously By etching an inverted T-shaped parasitic strip at the back plane of an antenna that is surrounded by a dielectric resonator (DR), the second band rejection is created By cutting a slot at the proper position on the ground plane, the width of the second band notch is controlled The proposed antenna size is $12 \times 30 \times 6~\hbox{mm}^{3}$ or about $0124 \lambda \times 031 \lambda \times 0062 \lambda $ at 31 GHz The measurement results demonstrate that the proposed DRA provides acceptable radiation performances such as an ultra-wide impedance bandwidth of around 122% with two sufficient band rejections in the frequency bands of 322–406 and 484–596 GHz, high radiation efficiency, and nearly constant gain

Slow-light enhanced subwavelength plasmonic waveguide refractive index sensors

Abstract: We introduce slow-light enhanced subwavelength scale refractive index sensors which consist of a plasmonic metal-dielectric-metal (MDM) waveguide based slow-light system sandwiched between two conventional MDM waveguides. We first consider a MDM waveguide with small width structrue for comparison, and then consider two MDM waveguide based slow light systems: a MDM waveguide side-coupled to arrays of stub resonators system and a MDM waveguide side-coupled to arrays of double-stub resonators system. We find that, as the group velocity decreases, the sensitivity of the effective index of the waveguide mode to variations of the refractive index of the fluid filling the sensors as well as the sensitivities of the reflection and transmission coefficients of the waveguide mode increase. The sensing characteristics of the slow-light waveguide based sensor structures are systematically analyzed. We show that the slow-light enhanced sensors lead to not only 3.9 and 3.5 times enhancements in the refractive index sensitivity, and therefore in the minimum detectable refractive index change, but also to 2 and 3 times reductions in the required sensing length, respectively, compared to a sensor using a MDM waveguide with small width structure.

High-Efficiency Harmonic-Peaking Class-EF Power Amplifiers With Enhanced Maximum Operating Frequency

Abstract: The recently introduced Class-EF power amplifier (PA) has a peak switch voltage lower than that of the Class-E PA. However, the value of the transistor output capacitance at high frequencies is typically larger than the required Class-EF optimum shunt capacitance. Consequently, soft-switching operation that minimizes power dissipation during off-to-on transition cannot be achieved at high frequencies. Two new Class-EF PA variants with transmission-line load networks, namely, third-harmonic-peaking (THP) and fifth-harmonic-peaking (FHP) Class-EF PAs are proposed in this paper. These permit operation at higher frequencies at no expense to other PA figures of merit. Analytical expressions are derived in order to obtain circuit component values, which satisfy the required Class-EF impedances at fundamental frequency, all even harmonics, and the first few odd harmonics as well as simultaneously providing impedance matching to a 50- $\Omega$ load. Furthermore, a novel open-circuit and shorted stub arrangement, which has substantial practical benefits, is proposed to replace the normal quarter-wave line connected at the transistor's drain. Using GaN HEMTs, two PA prototypes were built. Measured peak drain efficiency of 91% and output power of 39.5 dBm were obtained at 2.22 GHz for the THP Class-EF PA. The FHP Class-EF PA delivered output power of 41.9 dBm with 85% drain efficiency at 1.52 GHz.

A Tri-Band Bandpass Filter With Wide Stopband Using Asymmetric Stub-Loaded Resonators

Abstract: This letter presents a tri-band bandpass filter (BPF) with a wide stopband using asymmetric stub-loaded resonators (ASLR). A tri-band filter sample was fabricated by using two ASLRs with coupled I/O ports. By properly tuning the electrical length ratios of the ASLRs ( $\alpha$ and $\gamma$ ), three passbands can be designed at 1.4, 2.4, and 3.5 GHz. The harmonic responses are suppressed effectively by forming an uncoupled section at the end of the ASLRs, and the stopband region is formed from 3.7 to 7 GHz with a rejection level of 30 dB. The measured results of the fabricated tri-band BPF exhibit good agreement with simulated results.

Compact Dual-Band Bandpass Filters Using Open-/Short-Circuited Stub-Loaded $\lambda/4$ Resonators

Abstract: Two types of modified open- or short-circuited stub-loaded $\lambda/4$ resonator and their applications to second- order dual-band bandpass filters are presented in this letter Based on the resonance characteristics analysis, it is found that the first two resonant frequencies of the two resonators can be independently controlled Furthermore, different frequency ratios can be achieved by loading different stubs Finally, to illustrate the proposed idea, two second-order dual-band filters with controllable bandwidths are designed, fabricated and measured The measured results are in good agreement with the full-wave simulation results

Mechanical behavior of circular and square concrete filled steel tube stub columns under local compression

Abstract: This paper presents a combined experimental and numerical study on the behavior of both circular and square concrete-filled steel tube (CFT) stub columns under local compression. Twelve circular and eight square CFT stub columns were tested to study their bearing capacity and the key influential parameters. A 3D finite element model was established for simulation and parametric study to investigate the structural behavior of the stub columns. The numerical results agreed well with the experimental results. In addition, analytical formulas were proposed to calculate the load bearing capacity of CFT stub columns under local compression.

Compact planar UWB MIMO antenna with on-demand WLAN rejection

Abstract: Presented are two different frequency reconfigurable ultra-wideband multiple-input multiple-output (MIMO) antenna array designs capable of rejecting on-demand all WLAN communications in the 4.8 to 6.2 GHz range. Both arrays consist of two monopole UWB radiators placed orthogonally with respect to each other to introduce polarisation diversity and a quarter-wave stub connected to the ground plane via pin diodes is used to introduce the on-demand band rejection feature. One array design has separate ground planes and the other has two ground planes connected with a printed conductor (i.e. shared). For both cases, an isolation better than 20 dB between the elements is achieved in the 2 to 12 GHz frequency range with simulations and a manufactured prototype.

Experimental Investigation on the Local Buckling Behavior of 960 MPa High Strength Steel Welded Section Stub Columns

Abstract: Although high strength steel has been applied in many buildings and bridges, the application and researches of 960 MPa high strength steel are still quite limited. In order to investigate the local buckling behavior of 960 MPa high strength steel welded section stub columns under axial compression, an experimental program including 8 box and I-section members was conducted. Based on the test results, the local buckling strength and ultimate strength of each specimen were investigated. A finite element model validated through the test results was used to perform a parametric analysis, including 13 box section stub members and 33 I-section stub members with different width-to-thickness ratios. Compared with the corresponding design methods in GB 50017-2003, ANSI/AISC 360-10 and Eurocode 3, it was confirmed that the design methods about the local buckling behavior of 960 MPa high strength steel welded section stub columns under axial compression need to be modified.

Dual-band in-phase filtering power dividers integrated with stub-loaded resonators

Abstract: A compact microstrip dual-band in-phase filtering power divider is presented in this study The integrated two stub-loaded resonators are applied to realise the dual-band filtering response and compact size Based on the even–odd-mode analysis, an analytical model of the proposed power divider structure is presented To improve the frequency selectivity, a source-load cross coupling is introduced by placing input and output coupling lines closely A prototype of the dual-band in-phase filtering power divider centred at 35 and 5 GHz with 3 dB fractional bandwidth of 74 and 42% is designed, fabricated and measured The size of the fabricated power divider is 027λ g × 035 λ g The simulated and measured results are presented and show good agreement

Compact CPW-fed triple-band antenna for diversity applications

Abstract: A compact coplanar waveguide (CPW)-fed triple-band monopole antenna with high-band isolation for various wireless applications is presented. The proposed antenna is composed of a CPW-fed structure and a hexagon-shaped patch on which a hexagon-shaped slot is etched for covering the wireless local area network (WLAN) band (2.4/5.2/5.8 GHz), and occupies a very compact size of 26 × 25 mm2. By introducing a half-hexagon-shaped stub, additional bands can be realised covering the worldwide interoperability for microwave access (WIMAX) band (2.5/3.5/5.5 GHz). The proposed antenna has been fabricated and measured; results show a higher isolation between adjacent bands, good radiation pattern characteristics and stable gains in the operating bands. The simple feeding structure, compact size and uniplanar design make it easy to be integrated within portable devices for wireless communication.

Spectral Splitting Based on Electromagnetically Induced Transparency in Plasmonic Waveguide Resonator System

Abstract: Spectral splitting is numerically investigated based on the electromagnetically induced transparency (EIT) in a nanoscale plasmonic waveguide resonator system, which consists of a square ring resonator coupled with a stub-shaped metal-insulator-metal (MIM) waveguide. Simulation results show that the transparency window can be easily tuned by changing the geometrical parameters of the structure and the material filled in the resonators. By adding another stub or (and) square ring resonator, multi-EIT-like peaks appear in the broadband transmission spectrum, and the physical mechanism is presented. Our compact plasmonic structure may have potential applications for nanoscale optical switching, nanosensor, nanolaser, and slow-light devices in highly integrated optical circuits.

Multiband Metallic Frequency Selective Surface With Wide Range of Band Ratio

Abstract: A novel metallic multiband frequency selective surface (FSS) is presented. The proposed FSS structure has operation bands from closely spaced to far from each other (wide range of band ratio) and has high selectivity at each operation band. The unit cell comprises four small square slots, each loaded with multiple stub resonators. The stubs are placed in each slot in such a way that the unit cell response to both TE and TM polarizations are the same. To miniaturize the unit cell and cover the lower frequency range, each stub resonator is terminated with a U-shaped section. The length of each stubs within the slot determine the resonant frequency of each passbands. The band ratio can be set from 1.09 (close to each other) up to 2.35 (far from each other). Single, dual, triple, and quad band FSS structures are designed and simulated through HFSS software package. The fabricated dual-band unit cell shows that the proposed FSS structure can provide two close to each other bands, 9.8 and 10.9 GHz. Also, the measured results of a fabricated dual-band ${\bf 17} \times {\bf 17}$ FSS array show a relatively stable response to variations of incidence angle and polarization state.

A Novel Quad-Band Bandpass Filter Using Short Stub Loaded E-Shaped Resonators

Abstract: In this letter, a novel quad-band bandpass filter (BPF) using short stub loaded E-Type resonators is proposed. Two sets of resonators are utilized and respectively designed to realize Filter 1, operating at 2.4 and 3.5 GHz, and Filter 2 with two very closely spaced passbands, operating at 5.2 and 5.8 GHz. Then the two dual-band BPFs are combined by common feed lines with interdigital capacitance structure for quad-band responses, and two more transmission zeros (TZs) are achieved by strengthening the source-load coupling. The measured result of the fabricated filter agrees well with the simulation, which shows that the proposed structure is a good candidate for quad-band BPF designs and validates the proposed design flow well.

Active Impedance of Infinite Parallel-Fed Continuous Transverse Stub Arrays

Abstract: This paper introduces a rigorous and effective modeling framework for the continuous transverse stub (CTS) array, based on a spectral Green’s function approach. A multimodal expansion of the equivalent currents over the slots is used to derive an accurate expression for the active impedance of an infinite array. This formula is validated through comparisons with full-wave simulations when the array scans are in principal planes. The mathematical formulation highlights the broadband properties of CTS arrays and accurately predicts the impact of the geometrical parameters on the active impedance, as a function of frequency and scan angle. The discussion of the results provides physical insights to outline effective design strategies.

Design of Miniaturized HTS Dual-Band Bandpass Filters Using Stub-Loaded Meander Line Resonators and Their Applications to Tri-Band Bandpass Filters

Abstract: We have designed a miniaturized high-temperature superconducting dual-band bandpass filters (DBPFs) using stub-loaded meander line resonators and their applications to tri-band bandpass filters (TBPFs). The DBPF enables independent control of the center frequencies of the first and second bands. The bandwidths of the DBPF can be flexibly adjusted using a capacitance-loaded microstrip line between the resonators. The DBPF was designed and analyzed using an electromagnetic simulator and fabricated using an YBa 2 Cu 3 O y thin film on an Al 2 O 3 substrate. The center frequencies are 3.5 and 5.0 GHz; two bands have 2% bandwidth. The measured frequency responses of the DBPF were in good agreement with the simulated frequency responses. The TBPF was realized by combining the DBPF and a single-band bandpass filter (SBPF) that uses a folded stepped-impedance resonator with common input and output. The DBPF constructs the first and third bands of 3.5 and 5.0 GHz, and the SBPF forms the second band of 4.25 GHz. The frequency responses of the simulated TBPF meet the design parameters.

Numerical investigation of a nano-scale electro-plasmonic switch based on metal-insulator-metal stub filter

Abstract: We present a nano-scale electro-plasmonic scheme operating at 1550 nm based on plasmonic Metal-Insulator-Metal waveguide and stub filter configuration. The linear dependency of the transmission spectra of the stub filter to the length of the stubs allows designing a switch that works as normally ON or OFF switch by selecting the length of the stubs 300 or 410 nm, respectively. In our proposed waveguide-based structure, the core is an electro-optic material known as 4-dimethyl-amino-Nmethyl-4-stilbazolium tosylate with the refractive index 2.2 while the metal cladding is silver. Three-dimensional Finite Element Method simulations demonstrated that by applying a 10 V voltage to the silver cladding, a red-shift in the transmission spectra of the filter leads to turn the switch OFF or ON with calculated extinction ratio \(-13.83\) and 11.81 dB, respectively. The calculation of the capacitance implies that the switching rise-time of the switch is less than 20 fs and the bandwidth is far beyond the 18 GHz. At the maximum dimension \(460\,\hbox {nm}\times 450\,\hbox {nm}\), the subwavelength size of the switch promises the potential for future compact integrated plasmonic circuitry. For the verification of three dimensional simulation results, we have tried it, using two-dimensional transmission line method for modeling the stub filter, which demonstrates a reasonable accuracy in comparison with three-dimensional finite element method.

Enhanced Topology of $E$ -Plane Resonators for High-Power Satellite Applications

Abstract: A new $E$ -plane filtering structure suitable for very high-power telecom satellite applications is presented. The conceived configuration exploits the design flexibility provided by cascading highly integrated step/stub resonators with pseudoelliptic frequency responses. Several design examples of filters and diplexers in Ku-, K-, and Q-band are reported and supported by experimental tests campaigns. The components have been designed with a full-wave 2-D spectral element method. Prototypes have been realized in aluminum clam-shell technology. Excellent agreement between the models and the experimental results has been achieved. An alternative manufacturing of the proposed architecture based on the selective laser melting technology is also reported. The attractiveness of the structure in view of this emerging additive manufacturing solution is demonstrated. The main advantages of the proposed filter configuration suitable for components operated in heavily loaded multi-carrier environment are: compact design, very low losses, high rejection, and high power-handling capability.

Infrared plasmonic refractive index-sensitive nanosensor based on electromagnetically induced transparency of waveguide resonator systems

Abstract: We propose an infrared plasmonic refractive index-sensitive nanosensor based on the electromagnetically induced transparency (EIT) of waveguide resonator systems. The structure consists of one tooth-shaped cavity as well as the bus and stub metal–insulator–metal waveguides. By adjusting the structural geometry, it is demonstrated that the controllable transmission of EIT response can be obtained with the coupled-mode theory and the finite-difference-time-domain simulations. It is found that the transmission spectra dip at the spectra can be strongly controlled by changing the refractive index filled in the stub waveguide. The calculated results show that the sensitivity, full width at half-maximum and figure of merit of plasmonic nanosensor are 733 nm/RIU, 24.11 nm and 695, respectively. With the compact structure, the nanosensor may have great potential to be used in the field of integrated optoelectronics.

Tunable Slow Light Based on Plasmon-Induced Transparency in Dual-Stub-Coupled Waveguide

Abstract: We investigate the plasmon-induced transparency (PIT) effect in dual-stub-coupled metal-insulator–metal waveguide. The transmission line theory is employed to analyze the relationship between the transmission properties and geometrical parameters. It is found that by incorporating tunable refractive index materials with the proposed structure, a tunable PIT and slow light effect can be obtained in a constant stub separation design. The theoretical results show that a shift of 70 THz in the central wavelengths of transparency window can be obtained when the refractive index of the dielectric varies. In addition, the group index can be tuned from 24 to 36, which provides an effective method to adjust the slow light properties in the proposed waveguide. This letter opens up the possibility for the realization of tunable slow light devices in highly integrated optical circuits.

Design of a compact dual-band-notch ultra-wideband bandpass filter based on wave cancellation method

Abstract: In this study, a compact ultra-wideband (UWB) bandpass filter (BPF) with sharp roll-off, improved out-of-band performance and dual-band-notch operation is presented and its design procedure is discussed. In the proposed structure, in order to reject the unwanted harmonic pass bands, a pair of modified cross-shaped coupled lines (CCLs) is implemented along the ports of the filter. Moreover, a pair of half-circle-shaped stubs and a stepped-impedance stub are loaded on the main resonator in order to obtain additional transmission zeros (TZs) which are controllable separately. Implementation of the CCLs and the stub loaded resonator (SLR) reduce the total size of the presented microstrip BPF. Besides, by extending and folding the upper coupled line of each CCLs and also through an open stub which is protruded inside a slot on the main resonator, dual-band-notch operation is added to the performance of the presented filter. The fabricated prototype has a small size and is capable to cover frequency band of 2.8–10.69 GHz with two band-notch functions at 4.9–5.4 and 7.83–8.25 GHz which suppresses the interference between UWB spectrum with wireless local area network (WLAN) and satellite communication frequency bands, respectively. The proposed filter has a compact size while showing good return loss and insertion loss characteristic in the frequency band of interest.

A small ACS-fed tri-band antenna employing C and L shaped radiating branches for LTE/WLAN/WiMAX/ITU wireless communication applications

Abstract: A compact asymmetric coplanar strip (ACS)-fed monopole antenna with tri-band operation for LTE 2500, 2.4/5.2 GHz WLAN, 2.5 GHz WiMAX, 8 GHz ITU applications is presented in this paper. The proposed antenna design, which occupies an overall size of 14 ? 26 mm2 including ground plane, is composed of an ACS feedline with rectangular stub, C-shaped and L-shaped branches. The C-shaped radiating element is used to generate 2.5 GHz first resonant mode, L-shaped branch is used to generate second resonant mode at 5.2 GHz and ACS with rectangular shaped stub is aimed to generate a third resonance at higher frequency bands between 7.0 and 8.8 GHz.The measured impedance bandwidths (|S11| ≤ ?10 dB) are about 285 MHz (2.4---2.685 GHz), 380 MHz (5.0---5.38 GHz) and 3.5 GHz (6.5---10.0 GHz) for the three operating band, respectively. The experimental result shows a reasonable good agreement with the simulated results.

Band gap and defect state engineering in a multi-stub phononic crystal plate

Abstract: In this paper, we investigated the characteristics of band gaps and defect states in a locally resonant phononic crystal structure consisting of multiple square stubs deposited on both sides of a thin homogeneous plate Using the finite element method and supercell technique, we calculated the dispersion relationships and power transmission spectra of this structure, which agree well with each other This structure offers wide band gaps at extremely low frequencies Moreover, we investigated how the band gaps are affected by the distance between two adjacent square stubs, finding that acoustic band gaps are very sensitive to the distance between two adjacent square stubs, a property important for practical applications Based on this finding, we proposed a novel method to form phononic crystal structure defect: Defect bands can be induced by creating defects inside the original complete band gaps The frequency can then be tuned by changing the distance between two adjacent square stubs of the defect scatterer These results will help in fabricating devices, such as acoustic filters and waveguides whose band frequency can be modulated

Compact lowpass filter with wide stopband using coupled rhombic stubs

Abstract: A compact and high selective lowpass filter (LPF) with wide stopband is presented using coupled rhombic stubs. The proposed LPF unit is constructed by loading a rhombic stub on a transmission line. Then, a folded three-element LPF is proposed to achieve compact size and high selectivity by introducing coupling between adjacent rhombic stubs. The operating mechanism of the filter is investigated and explained, by adopting the physically-based LC-equivalent circuit model. The implemented final LPF exhibits a wide stopband of up to 11.5 f c with a rejection level of better than 35 dB. Furthermore, the final LPF features a compact size of 0.12λ g × 0.10λ g, where λ g is the guide wavelength of f c, and a very high figure-of-merit (FOM) of 27 142.