Showing papers on "Stub (electronics) published in 2021"

QMSIW-Based Single and Triple Band Bandpass Filters

Abstract: This brief proposes compact and planar substrate integrated waveguide (SIW)-based filters for single and triple band operations using two quarter-mode SIW (QMSIW) cavities Two miniaturized QMSIW cavity resonators (QMSIWCRs) are capacitively coupled Miniaturization in the QMSIWCR is achieved by adding an arc-shaped slot and a rectangular open-ended stub at the closed-end of the QMSIWCR In the triple band bandpass filter (BPF), a capacitor is added to the open-ended side of the stub to enhance impedance matching at the higher modes It has the centre frequencies of 21, 398 and 66 GHz with an insertion losses (ILs) of 093, 098, and 12 dB at the lower, middle and upper passband, respectively Moreover, the measured fractional bandwidths (FBWs) are 1697, 877, and 842% at the lower, middle and upper passband, respectively Two rectangular slots are etched on the upper layer of the cavity to suppress the second mode and reduce coupling of the third mode; this realizes a single-band filter with an improved upper stopband response It has the centre frequency of 21 GHz with a wide upper stop-band response, having a rejection level of 20 dB up to $319f_{c}$ The operation of filter is additionally discussed and verified by means of a lumped element equivalent circuit model and experimental results The proposed filters are suitable for integration with other planar radio-frequency (RF) components due to their compact sizes, low ILs, planar structures, multiple transmission zeros (TZs) and adequate bandwidths

A Flexible and Pattern Reconfigurable Antenna with Small Dimensions and Simple Layout for Wireless Communication Systems Operating over 1.65–2.51 GHz

Abstract: This research article proposes a compact frequency and pattern reconfigurable flexible antenna for heterogeneous applications. A triangular monopole antenna with a semicircular stub is made frequency and pattern tunable by connecting and disconnecting two inverted L-shaped stubs utilizing diodes. When either of the stubs is connected to the radiator, a relative phase difference happens at both ends of the radiator that changes the direction of the electromagnetic radiations, consequently pattern reconfigurability can be obtain. Besides that, because of the reactive load introduced by the stubs, the antenna’s effective length has changed and, as a result, the frequency reconfigurability can be attained. The antenna features a compact size of 40 × 50 × 0.254 mm3 corresponding to 0.22λo × 0.27λo × 0.001λo, where λo is free-space wavelength at 1.65 GHz, while its operational bandwidth is from 1.65 GHz to 2.51 GHz, with an average gain and radiation efficiency of better than 2.2 dBi and 80%, exhibiting a pattern reconfigurability of 180° in the E-plane. The frequency of the proposed antenna can be switched from 2.1 GHz to 1.8 GHz by switching the state of both diodes in OFF and ON-state, respectively. The fabricated prototype of the antenna is tested to verify its performance parameters. In addition, to validate the proposed design, it has been compared with prior arts in terms of the overall size, reconfigurability type, flexibility, radio frequency (RF) switch type used for reconfigurability, and frequency bandwidth. The proposed antenna provides smaller size with a large bandwidth coverage alongside with discrete RF switch type with the advantages of flexibility and both frequency and pattern reconfigurability. As a result, the proposed compact flexible and pattern reconfigurable antenna is a promising candidate for heterogeneous applications, including the global system for mobile (GSM) band (1800 and 1900 MHz) and industrial, scientific and medical (ISM) band (2.4 GHz) along with well-known cellular communication bands of 3G, 4G, and long term evolution (LTE) bands ranging from 1700–2300 MHz around the globe.

Mutual Coupling Reduction Using Ground Stub and EBG in a Compact Wideband MIMO-Antenna

Abstract: This paper presents a compact, uni-planer wide band Multiple-Input-Multiple-Output (MIMO) antenna. The designed antenna array has a compact size of (26mm x 31mm) covering a wide frequency band from 3.1GHz - 11GHz. A partial ground plane shared by two radiating patches is used. A ground stub and a single column Electromagnetic Bandgap (EBG) structure in between the two radiating patches results in very low mutual coupling in the designed antenna. The proposed MIMO-antenna was evaluated through different performance metric indicators like channel capacity loss, far-field radiation pattern, S-parameters, envelope correlation coefficient, peak gain, diversity-gain and radiation efficiency. Our designed MIMO antenna has a very high isolation amongst the MIMO antennas ( $\text{S}_{21} dB), a high Diversity-Gain (DG $>9.995$ dB), a very low Envelope Co-relation Coefficient of (ECC < 0.001) and low Channel-Capacity-Loss (CCL < 0.1bits/s/Hz). The said antenna has an average radiation efficiency of 85.5% and a peak gain of (5.67dB) within the ultra-wideband (UWB) spectrum. A 0.8mm thick FR-4 substrate is used to fabricate the MIMO-antenna and tested in an anechoic chamber. The measured results closely match with the simulated results.

A 5.8-GHz Band Highly Efficient 1-W Rectenna With Short-Stub-Connected High-Impedance Dipole Antenna

Abstract: This article describes a 5.8-GHz band highly efficient 1-W rectenna that consists of a bridge diode, directly connected to a short-stub-connected high-impedance dipole antenna, with a designed antenna resistance of $580~\Omega $ . The proposed antenna topology realizes circuit functionalities of impedance transform, impedance matching, harmonic reaction, and dc blocking while maintaining a high antenna radiation efficiency. Lossy circuit components between the antenna radiator and the bridge diode can be eliminated for a highly efficient rectification. In experimental investigations, the measured rectification efficiency of the 5.8-GHz band rectifier is 92.8% at an input power of 1 W, and the estimated antenna radiation efficiency from the measured antenna gain is 96.9%, including loss due to circuit functionalities and interconnection. With lesser additional losses, the proposed antenna can be integrated with circuit functionalities to achieve a highly efficient rectenna. The measured rectification efficiency is almost the same as the fundamental limitation restricted by the rectifier diodes’ performance.

Efficient Dual-Band Rectifier Using Stepped Impedance Stub Matching Network for Wireless Energy Harvesting

Abstract: This letter presents an efficient dual-band rectifier using stepped impedance stub matching circuit. Theoretical analysis of the dual-band impedance matching circuit comprising a stepped impedance stub is carried out, which plays a key role in designing the resultant dual-band rectifier. The proposed dual-band matching circuit can achieve wide frequency ratio which is analyzed and predicted by simulation. For demonstration, a dual-band rectifier working at 0.915 and 2.45 GHz is fabricated with dimensions of 21.47 mm $\times18.93$ mm. The measured results show that with a $1500~\Omega $ load, the maximum efficiencies of the rectifier reach 74% and 73% at 0.915 and 2.45 GHz, respectively. Due to the simple but efficient structure of the dual-band matching network, the dual-band rectifier in this work exhibits merits of compact size and high efficiency.

Design of a wearable MIMO antenna deployed with an inverted U-shaped ground stub for diversity performance enhancement

Abstract: A compact multiple input multiple output (MIMO) antenna operating at 2.45 GHz industrial scientific and medical band is presented for wearable devices. Open-end slotting is used to miniaturize the antenna dimensions. Inverted U-shaped ground stub is incorporated to reduce mutual coupling. On-body performance is analyzed on a three-layered equivalent tissue phantom model. The wide bandwidth of 300 MHz and port isolation of 30 dB are obtained from measured results. The antenna shows the efficiency of 40% and directivity of 4.56 dBi when placed at a gap of “s” = 4 mm from the body. Broadside radiation pattern and low specific absorption rate make the antenna suitable for on-body communication. Further, diversity performance is measured in terms of envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CCL). The value of ECC is 0.025, DG is 9.98 dB, and CCL is 0.12 bits/s/Hz at 2.45 GHz. Antenna robustness is examined by bending the structure at different radii along the x-axis and y-axis. Performance of the proposed structure is reliable with structural deformation.

Ultra-Wideband Rectenna Using Complementary Resonant Structure for Microwave Power Transmission and Energy Harvesting

Abstract: An ultra-wideband (UWB) rectenna (fractional bandwidth >100%) using a novel wideband complementary matching stub is proposed for microwave power transmission and energy harvesting A simple resonant structure, ie, LC series–parallel resonant circuit, is embedded to the L-shaped complementary matching stub Due to the unique frequency response of the LC resonant circuit, the proposed matching stub can exhibit “open” and “short” circuits as a function of frequency, thereby acting as a complementary matching circuit covering a relatively wide frequency range Having utilized the proposed matching stub, the nonlinear input impedance of the rectifier can be tuned to conjugately match the antenna impedance throughout the frequency band of interest Simulated and measured results show that the proposed rectenna has good matching performance ( $S_{11} dB) and high RF-dc conversion efficiency (>50%) over a relatively wide frequency range from 09 to 3 GHz (for GSM, Wi-Fi, and WLAN bands) The maximum conversion efficiency of 734% is realized at 3-dBm input power It is evident that the proposed resonant structure-based matching scheme is a promising and effective solution to facilitate the UWB rectenna design with stably high efficiency over a very wide frequency band

A compact double-band planar printed slot antenna for sub-6 GHz 5G wireless applications

Abstract: A planar rectangular slot antenna with dual-band operation and realized higher peak gain is proposed, designed, and fabricated for sub-6 GHz 5G applications. The antenna possesses a rectangular radiating slot with the inverted stub on its upper edge excited simultaneously by a micro-strip feed line having a double folded T-shaped structure. The fabricated design is of compact size with the radiating portion of 0.3 λ0 × 0.17 λ0 (λ0 represents free-space wavelength) and profile of 0.009 λ0. The measured results show the operating frequency bands of 3.29–3.63 GHz and 4.3–5.2 GHz, with a peak gain of around 7.17 dBi. The higher frequency band is generated by the feed patch and the slot whereas lower resonant frequency band is generated by the stub loaded on the slot. The measured results are in a good agreement with the simulated results. The proposed design is suitable for the International Telecommunications Union sub 6 GHz applications.

Two-Port CPW-Fed Dual-Band MIMO Antenna for IEEE 802.11 a/b/g Applications

Abstract: A coplanar waveguide- (CPW-) fed dual-band multiple-input multiple-output (MIMO) antenna for 2.45/5.5 GHz wireless local area network (WLAN) applications is presented in this paper. The presented MIMO antenna consists of two identical trapezoidal radiating elements which are perpendicular to each other. The size of the entire MIMO antenna is 50 × 50 × 1.59 mm3, which is printed on a FR4 substrate. The measured impedance bandwidth of the proposed antenna is 2.25–3.15 GHz and 4.89–5.95 GHz, which can cover IEEE 802.11 a/b/g frequency bands. A rectangular microstrip stub is introduced to achieve a good isolation which is less than −15 dB in both operation frequency bands. The measured peak gain is 5.59 dBi at 2.45 GHz and 5.63 dBi at 5.5 GHz. The measured antenna efficiency is 77.8% and 80.4% in the lower and higher frequency bands, respectively. The ECC values at the lower and higher frequencies are lower than 0.003 and 0.01, respectively.

Simulation and fabrication of a high-isolation very compact MIMO antenna for ultra-wide band applications with dual band-notched characteristics

Abstract: In this paper a very compact dual band-notched two-port multiple-input multiple-output antenna with low mutual coupling is presented for portable ultra-wideband systems. This antenna with overall size 18 × 35 × 1.6 mm3, consist of two identical monopole elements which fed by two 50 Ω coplanar waveguide lines and fabricated adjacent to each other on the top side of a FR-4 substrate with shared ground plane. To reduce the mutual coupling between elements, a rectangular stub was introduced between them and then it modified to a T-shaped stub. For further reduction, a rectangular slot etched out of the connected ground plane. Due to the results, proposed antenna achieves wide impedance bandwidth at each port, from 2.3 to 12 GHz covering the whole UWB spectrum except at two eliminating bands. Although this antenna has small size and simple structure, the mutual coupling between elements is lower than −20 dB. By etching out two rectangular single complementary split-ring resonators from the radiating patch, dual band-notched characteristics are obtained in WiMAX and WLAN bands. Envelope correlation coefficient of less than 0.035, nearly omnidirectional pattern, 90% radiation efficiency despite lossy substrate, high multiplexing efficiency (>−1 dB) except at two notches and peak gain near 6dBi are some other characteristics of this design.

Dielectric Characterization of Liquid Mixtures Using EIT-like Transmission Window

Abstract: Electromagnetically induced transparency (EIT) is a destructive interference phenomenon which has been widely reported in both quantum and classical wave systems. In an EIT-like system, sharp transmission windows appear within stop bands, indicating potentials in sensor applications. In this work, we design a planar microwave circuit with an EIT-like spectrum for dielectric characterization of liquid mixtures. The sharp EIT-like transmission window relies on the strong coupling between an open-circuited stub and a split ring resonator, which are sensitive to surrounding environment. Binary liquid mixtures of water-ethanol and water-methanol are injected into the container fixed on the surface of the sensitive area. Complex permittivity of the liquid under test affects both the center frequency and the quality factor of the EIT-like transmission window. Thus, complex permittivity of liquid mixtures can be further retrieved from measured S21. Measurements together with theoretical and numerical analysis are discussed in detail and results match well with Debye function. We also analyze the achievable high sensitivity (5%) of the proposed EIT-like sensor when measuring solid samples with low permittivity dynamic range and conduct experiments. The proposed design is easy to fabricate and can be used to test various materials.

CMA assisted 4-port compact MIMO antenna with dual-polarization characteristics

Abstract: In this paper, Characteristics mode analysis (CMA) is introduced to study the dual-polarization behavior of simple monopole antenna. The antenna consists of monopole feed with symmetric arms (SA), resonating at 2.45 GHz and right-handed stub (RHS) is connected to resonate at 5.8 GHz. The SA has linear polarization and RHS has circular polarization. CMA is introduced to explore dual-polarized properties and validated on modal metrics. The intuition of antenna design is further extended to 4-port MIMO antenna configuration. Due to rotationally symmetrical connected ground topology, another induced resonance at 1.54 GHz is observed. A L-shaped stub is further connected to one-end of the monopole arm of each antenna element, that function as 2.5 GHz resonator and an effective isolator. The overall antenna dimension is 0.3 λ × 0.3 λ × 0.018 λ (where λ is the lowest operating wavelength) and the elements are spatially separated with edge-to-edge spacing of 0.018 λ with port isolations > 15 dB. The MIMO antenna operates at 1.54 GHz, 2.5 GHz with linear polarization and at 5.63 GHz as circular polarization. The antenna gains with radiation efficiencies are 0.62 dBi ( > 60%), 4 dBi ( > 70%) and 4.25–6 dBc ( > 80%). The computed ECCfar−fields is 0.3, showing its potential for pattern and polarization diversity MIMO environments. A prototype antenna is fabricated and measured with good agreements and found compatible for L-band, lower WLAN and upper WLAN applications.

Experimental and Numerical Investigations of Octagonal High-Strength Steel Tubular Stub Columns under Combined Compression and Bending

Abstract: An experimental and numerical study on the octagonal high-strength steel tubular stub columns under combined compression and bending is presented in this paper. Octagonal high-strength stee...

Synchronism and Direction Detection in High-Resolution/High-Density Electromagnetic Encoders

Abstract: Recently, electromagnetic encoders with synchronous reading and direction detection capability have been reported. Such structures are useful for the implementation of (i) displacement/velocity sensors and (ii) chipless-RFID systems based on near-field coupling and sequential bit reading. In the latter, synchronous reading and motion direction detection are a need in order to avoid false readings of the identification (ID) code, if the relative velocity between the reader and the encoder is not constant, and to read the correct ID code (rather than the inverse one), respectively. On the other hand, synchronous reading and motion direction detection, are essential to determine the encoder direction in displacement/velocity sensors, as well as to provide the absolute position of the encoder, provided that the whole encoder is encoded with the Bruijn sequence. In this paper, synchronous reading and direction detection in high-resolution/high-density electromagnetic encoders based on chains of linearly-shaped metallic inclusions are reported. To this end, it is necessary to add two chains of metallic inclusions to the one containing the ID code. In the reader side, three harmonic signals are necessary in order to generate the clock signals and to obtain the ID code. The reader consists of a microstrip line loaded with three pairs of open-ended folded stubs positioned face-to-face by their extremes. By displacing the encoder chains over the extreme of the stubs, at short distance, stub coupling is enhanced when a metallic inclusion lies on top of the stubs, and the frequency response of the reader is shifted towards lower frequencies. Thus, by injecting three (properly tuned) harmonic signals at the input port of the microstrip transmission line, three amplitude modulated (AM) signals are generated by tag motion at the output port of such transmission line, and the envelope functions contain the velocity, the ID code and the absolute position. The reported reader/encoder system exhibits superior space resolution and information density as compared to other similar systems based on synchronous reading.

Dual-Band Antenna Pair With Lumped Filters for 5G MIMO Terminals

Abstract: This article proposes a novel design of the dual-band antenna pair. Starting from the single-band antenna pair composed of T-shaped monopole and T-shaped slot that are intersected with each other, orthogonal T-monopole and odd-symmetrical slot modes are excited. By adding symmetrical low-pass high-stop filters into the horizontal stub of the T-monopole and high-pass low-stop filters into the gap of the T-slot, an extra mode is introduced for each antenna, producing dual-band operation. Impedance bandwidths and radiation efficiencies of both bands can be adjusted flexibly using the filters. A detailed design guideline is given. The dual-band antenna pair operating at partial N78 (p-N78, 3.4~3.6 GHz) and partial N79 (p-N79, 4.8~4.9 GHz) is with a footprint of $15\times 6$ mm2. The measured results show that the average efficiencies are both −3.4 dB at p-N78/p-N79 for the odd-symmetrical slot and −2.8 dB/−3.7 dB at p-N78/p-N79 for the T-monopole, isolations are better than −16.8 dB at p-N78 and −11.8 dB at p-N79, and ECCs are lower than 0.1 at p-N78 and 0.2 at p-N79. The proposed dual-band antenna pair exhibits great potential to be applied in the fifth-generation (5G) multiple-input multiple-output (MIMO) terminal.

A Novel Dual-Polarized Continuous Transverse Stub Antenna Based on Corrugated Waveguides—Part II: Experimental Demonstration

Abstract: We present the experimental validation of the dual-mode, polarization-agile parallel-fed continuous transverse stub (CTS) antenna architecture introduced in Part I of this two-part paper. The Ka-band dual-mode CTS array described in Part I is characterized when it radiates in horizontal and vertical polarization. To this end, it is combined with two different quasi-optical beamformers operating in a quasi-transverse electromagnetic (quasi-TEM) and in a quasi-transverse electric (quasi-TE1) mode, respectively. The scanning capabilities of both multibeam antenna systems are demonstrated. The CTS array and its feed network comprising corrugated parallel-plate waveguides (CPPWs) are fabricated by additive manufacturing. Measurements show that the dual-polarized CTS antenna works between 29 and 32 GHz in a field of view of about 45°, achieving a peak gain of 31.3 dBi and very low cross polarization. These promising results pave the way for the realization of dual-circularly polarized beam-scanning antennas with application to broadband and compact Ka-band ground terminals.

Membrane residual stresses and local buckling of S960 ultra-high strength steel welded I-section stub columns

Abstract: The membrane residual stresses and local buckling behaviour of S960 ultra-high strength steel welded I-section stub columns have been investigated through a comprehensive testing and numerical modelling programme. The testing programme included material testing, membrane residual stress measurements, initial local geometric imperfection measurements and sixteen stub column tests. On the basis of the measured data, a membrane residual stress predictive model was developed. Following the testing programme, a numerical modelling programme was conducted, where finite element models were firstly developed and validated against the test results and then adopted to conduct parametric studies to generate further numerical data. The obtained test and numerical data were used to assess the applicability of the relevant design provisions for S700 (or S690) high strength steel welded I-section stub columns, as given in the European code, American specification and Australian standard, to their S960 ultra-high strength steel counterparts. The assessment results generally revealed that (i) all three sets of codified slenderness limits can be accurately and consistently used for cross-section classification of S960 ultra-high strength steel welded I-section stub columns and (ii) the local buckling design provisions in the three design codes also lead to accurate and consistent cross-section compression resistance predictions.

A compact band-notched antenna with high isolation for UWB MIMO applications

Abstract: A compact antenna module with a single band notch at wireless local area network (WLAN) (5.725–5.825 GHz) for ultra-wideband (UWB) multiple input multiple output (MIMO) applications is proposed. Proposed antenna which acquires size of 0.299 λ × 0.413 λ × 0.005 λ mm3 at 3.1 GHz consists of two symmetrical radiators placed side by side on global merchandise link (GML) 1000 substrate (er = 3.2, tan δ = 0.004). Isolation between the antenna elements is >18 dB in the whole UWB band, which is achieved by introducing the vertical stub and H-slot between the monopole radiators in the ground plane. The simulated and measured results of the antenna system are in good agreement. The proposed antenna covers entire UWB with impedance bandwidth (|S11| < −15 dB) from 3.1 to 11 GHz except at WLAN notched band. The designed antenna module bears low envelope correlation coefficient and minimal multiplexing efficiency hence fulfilling criteria suitable for various wireless MIMO applications.

A Compact Planar Dual-Band Multiple-Input and Multiple-Output Antenna with High Isolation for 5G and 4G Applications.

Abstract: In this paper, a compact planar dual-band multiple-input and multiple-output (MIMO) antenna with high isolation is presented to satisfy the increasing requirements of wireless communication. The proposed antenna array consists of two identical radiating elements which are fed through micro-strip lines. A rectangular micro-strip stub with defected ground plane is employed to achieve a high isolation which is less than −15 dB between the two antenna elements. The size of the entire MIMO antenna is 32 × 32 × 1.59 mm3, which is printed on an FR4 substrate. The proposed MIMO antenna is optimized to operate in 2.36–2.59 GHz and 3.17–3.77 GHz bands, which can cover the fifth-generation (5G) n7 (2.5–2.57 GHz) and the fourth-generation (4G) Long Term Evolution (LTE) band 42 (3.4–3.6 GHz). The proposed MIMO antenna is feasible for the 5G and 4G applications.

Behavior and design of concrete-filled narrow rectangular steel tubular (CFNRST) stub columns under axial compression

Abstract: In recent years, the concrete-filled narrow rectangular steel tube (CFNRST) has drawn much attention for practical engineering applications. Compared with the commonly used concrete-filled rectangular steel tube (CFRST), the cross-sectional aspect ratio (the ratio between widths of wider and narrower sides of the steel tube) of CFNRST is larger and exceeds 2.0, which is considered as the upper limit of aspect ratios for ordinary CFRSTs reported in the literature. In this paper, experimental results are presented involving 24 specimens of CFNRST stub columns subjected to axial compression. The axial resistant behavior of CFNRST columns is investigated concerning the effects of key parameters including: (a) cross-sectional aspect ratio, (b) confining factor, and (c) width-to-thickness ratio of wider side of steel tube. By analyzing the observed and measured test results, the failure modes, ductility performance, strength enhancement effect and residual resistance of the specimens are discussed in detail. Moreover, 173 test results of CFRST stub columns under axial compression reported in the literature are collected and compared with the test results of this study; hence, the effect of extremely large cross-sectional aspect ratio on the behavior of CFRST columns is presented. Finally, typical equations specified in design codes are examined to reveal their validity in predicting the ultimate axial resistance of both CFNRSTs and ordinary CFRSTs. This study can provide valuable information for practical designs of CFNRST stub columns under axial compression.

A Wearable Flexible Energy-Autonomous Filtenna for Ethanol Detection at 2.45 GHz

Abstract: This work proposes the design and implementation of a wearable rectifying filtenna (filtering antenna) which is activated and powered wirelessly, to detect the presence of ethanol solutions. The system is implemented on a Rogers RT/Duroid 5880 substrate ( $\varepsilon _{r} =2.2$ and thickness: 0.508 mm), whose flexibility facilitates the system wearability. The fluid detection is performed by a resonant stub embedding a microfluidic channel on its end, which resonates as an open circuit at 2.45 GHz when the channel is filled with the ethanol solution and undergoes a dramatic shift on its input impedance behavior when the channel is filled with water or when it is empty. The system is powered wirelessly by means of a 2.45-GHz narrowband antenna, and the frequency selection is performed by a second-order open-end coupled-line filter whose one end is loaded with the resonant stub. The filtenna RF signal is transduced by a full-wave rectifier exploiting low-threshold voltage diodes, and fluid detection is read out through different values of dc-output voltages, allowing an immediate response. The system is designed and optimized by means of full-wave/nonlinear co-simulations and the realized prototype is measured to confirm a safe detection of the tested solution.

Compact self decoupled MIMO antenna pairs covering 3.4–3.6 GHz band for 5G handheld device applications

Abstract: A self-decoupled 4-port multiple-input multiple-output (MIMO) antenna pair working in the midband of the 5G spectrum (3.5 GHz) for handheld device application is presented in this paper. The antenna includes two vertically placed blocks printed exactly at the middle of the two lengthy frames of the handheld device. The self-decoupled antenna pair structure consists of two monopole antenna separated by a distance of 7 mm, a T-shaped parasitic structure, and a stub at the backside connecting the ground plane. The monopole antennas are excited by a simple coaxial feeding structure. The T-shaped element not only serves as a radiator but plays a vital role in providing port isolation between the two ports to obtain a self-isolated antenna pair. The self-decoupled antenna pair operates from 3.4 to 3.6 GHz with isolation higher than −16.5 dB in the entire utilization band. The parametric analysis of the optimal parameters and the evolution design of the antenna pair is studied for a better interpretation of the working principle of the MIMO system. The total efficiency and peak gain of all the antennas are more than 78% and 5 dB respectively in the whole utilization bandwidth. The worst-case envelope correlation coefficient (ECC) value among the elements of the antenna pair is less than 0.03, which is less than the ideal value of 0.5. Other MIMO diversity parameters such as Channel Capacity Loss (CCL), Mean Effective Gain (MEG), Total Active Reflection Coefficient (TARC), and Diversity Gain (DG) of the designed antenna are calculated and analyzed with the measured results. A model of the designed handheld device is fabricated and analyzed. The measured results indicate the suitability of the design for a capable candidate in 5G handheld device applications.

Tunable Multiple Fano Resonances and Stable Plasmonic Band-Stop Filter Based on a Metal-Insulator-Metal Waveguide

Abstract: A metal-insulator-metal (MIM) waveguide consisting of two stub resonators and a ring resonator is proposed, which can be used as refractive index sensor and stop-band filter at the same time The transmission characteristics of the MIM waveguide structure is studied by the finite element method (FEM) The simulation results show that the typical Fano profile and multiple Fano resonances can be achieved According to the analysis, the range of stop-band and the multiple Fano resonance positions can be adjusted flexibly and independently by adjusting the aggregate parameters of the MIM waveguide structure Moreover, it is also found that the two Fano resonances at both ends of the stop band can be determined by the two stubs, and the other two Fano resonances are regulated by the ring resonator In addition, the spectral position of multi-Fano resonances is highly sensitive to the radius of the ring resonator and the refractive index of the filled medium The maximum sensitivity and the figure of merit (FOM) of the MIM waveguide structure are 1650 nm/RIU and 1178 in magnitude, respectively These results provide a reference for implementing high-sensitivity sensors and large-bandwidth stop-band filter in MIM waveguide coupling systems based on multi-Fano resonance effect

An Angular Displacement Microwave Sensor With 360° Dynamic Range Using Multi-Mode Resonator

Abstract: This article presents the application of a novel multi-mode resonator (MMR) named rotational cross-shaped resonator (RCSR) to the design of a planar angular displacement microwave sensor. This MMR developed by four connected stubs with short and open terminations. Since the generated transmission zeros of the RCSR vary linearly with changes in stub lengths, the RCSR structure that makes use of this principle is proposed for implementing angular displacement sensing. The sensor consists of an open-ended stub of RCSR housed by a circular rotor and the rest of the RCSR on the stator. As the position of the stub of RCSR is modified by rotating the rotor, the generated transmission zeros will drift accordingly. Based on the multiple zeros, the proposed angular displacement sensor can provide distinctive direction of rotation detection in addition to dual-sensing measures output. A sensor prototype at 1.95 GHz is designed and experimentally characterized, which reports that both the angle and direction of rotation detections can be realized. The average frequency sensitivity in terms of the variation of a single transmission zero is 1.22 MHz/degree for the dynamic range from −180° to 180°, as well as the average bandwidth sensitivity in terms of the frequency difference between two zeros is 2.61 MHz/degree for the dynamic range from 0° to 180°.