Showing papers on "Stub (electronics) published in 2020"

Broadband Eight-Antenna Array Design for Sub-6 GHz 5G NR Bands Metal-Frame Smartphone Applications

Abstract: A multiple-input–multiple-output (MIMO) antenna array for broadband 5G new radio (5G NR) metal-frame smartphone applications is proposed. The MIMO antenna array is realized by loading eight identical antennas (Ant1–Ant8) into the metal frame of the smartphone to form an eight-antenna array for the sub-6 GHz 8 × 8 MIMO system. Each antenna element is a slot antenna type that is composed of an L-shaped open slot and a 50 Ω microstrip feedline, and good impedance matching in the upper frequency band can be achieved by loading a tuning stub to the feedline. The 10 dB impedance bandwidth of the proposed eight-antenna array can cover the 5G NR Bands n77/n78/n79 and wireless local area network (WLAN) 5 GHz band. Besides demonstrating desirable antenna efficiency of 50%–82% and envelope correlation coefficient of 12 dB. At 20 dB signal-to-noise ratio (SNR), the calculated peak channel capacity of the proposed eight-antenna array applied to an 8 × 8 MIMO system is 43.93 b/s/Hz.

Wideband MIMO Antenna Array Design for Future Mobile Devices Operating in the 5G NR Frequency Bands n77/n78/n79 and LTE Band 46

Abstract: An eight-antenna array with wideband operation for future 5G New Radio mobile devices is studied. Each array element is composed of an inverted-F antenna with shorting branches and parasitic elements. The driving element (monopole structure) and the shorting element (inverted-L branch and inverted-C branch) enable the antenna to obtain multiple modes, whereas the parasitic element, open slit, and stub can improve the impedance matching. The 6 dB impedance bandwidth of the proposed eight-antenna array can completely cover the 5G Sub-6 GHz NR frequency Bands n77/n78/n79, which include the 5G band of U.S. (3.55–4.2 GHz), China, EU, and Japan (3.6–4.2 GHz and 4.4–4.9 GHz), as well as the LTE Band 46 (5.15–5.925 GHz). From the measured results, the isolation between adjacent array elements is lower than 10 dB and its corresponding envelope correlation coefficient is also lower than 0.1.

An ultra-compact two-port UWB-MIMO antenna with dual band-notched characteristics

Abstract: In this paper, an ultra-compact two-port MIMO antenna working in the frequency range of 3.1–10.6 GHz with dual band-notched characteristics is presented. The MIMO antenna consists of two identical octagonal-shaped radiating elements placed adjacent to each other with a connected ground plane. The overall size of the proposed two-port UWB-MIMO antenna is 19 × 30 × 0.8 mm3. In the ground plane of antenna elements, a T-shaped stub is introduced to create band-notch at 5.5 GHz. Also, an open-ended half-guided-wavelength resonator slot is introduced along the upper edge of the octagonal radiator to obtain a broader notched-band (4.37–5.95 GHz). The second band-notch is created around 7 GHz (6.52–7.45 GHz) by etching another open-ended slot from the radiating patch. The two-notch bands reject interference due to HiperLAN, WiMAX, INSAT/Super-extended C-band, downlink of X-band satellite communication and RFID service bands. A pair of L-shaped slits are introduced in the feed line to improve impedance matching, for the frequency band available between the two notches. The proposed design is fabricated on an FR-4 substrate and minimum isolation greater than 18 dB (a major portion >22 dB) and envelope correlation coefficient (ECC) less than 0.13 are obtained. The antenna gain varies in the range of 1.2–2.91 dBi with a variation of 1.71 dBi only. A radiation efficiency, greater than 70% is achieved throughout the operating frequency band.

A Compact Flexible Frequency Reconfigurable Antenna for Heterogeneous Applications

Abstract: This paper presents a compact frequency reconfigurable antenna for flexible devices and conformal surfaces. The antenna consists of a simple easy to fabricate structure consisting of a stub loaded circular radiator, designed on commercially available RT5880 flexible substrate ( $\varepsilon _{\mathrm {r}} = 2.2$ ) with a thickness of 0.254 mm. The combination of stub loading and slot etching techniques are utilized to achieve the advantages of compactness, frequency reconfigurability, wide impedance bandwidth, and stable radiation pattern with structural conformability. The frequency reconfigurability is achieved by employing two p-i-n diodes. Simulated and experimental results showed that the antenna operates in various important commercial bands, such as S-band (2 GHz– 4 GHz), Wi-Max (3.5 GHz and 5.8 GHz), Wi-Fi (3.6 GHz, 5 GHz, and 5.9 GHz), 5G sub-6-GHz (3.5 GHz and 4.4 GHz – 5 GHz), and ITU-band (7.725 GHz – 8.5 GHz) with the additional advantages of structural conformability. Furthermore, the performance comparison of the proposed flexible antenna with the state-of-the-art flexible antennas in terms of compactness, frequency reconfigurability, and number of operating bands demonstrates the novelty of the proposed antenna and its potential application in heterogeneous applications.

Shared-Aperture Variable Inclination Continuous Transverse Stub Antenna Working at K - and Ka -Bands for Mobile Satellite Communication

Abstract: A dual-band shared-aperture variable inclination continuous transverse stub (VICTS) antenna is designed with good port isolation and a low profile. The operation bands, including 19.5–20.1 and 28.8–29.6 GHz, locate at the regulated bands for $K$ - and Ka -band mobile satellite communication. The design principle is “shared radiating aperture and independent feeding networks,” which means two feeding networks are integrated to share one radiating aperture. At the center frequencies of the two operation bands, that is, 19.8 and 29.2 GHz, the beam-scanning coverage in elevation is $38^{\circ } \times 2$ and $60^{\circ } \times 2$ , respectively. The relative bandwidths in $K$ - and Ka -bands are 3.0% and 2.7%, respectively. The maximal gains for the two bands are 24.33 and 28.52 dBi. Good port isolation greater than 90 dB at the lower band and greater than 20 dB at the higher band is obtained. A low profile of only 10 mm is achieved, that is, 0.65 and $0.97~\lambda _{0}$ , at the center frequencies. This article is a good candidate for the $K$ - and Ka -band mobile satellite communication under the restriction of cost and size.

Eight-Element Compact UWB-MIMO/Diversity Antenna With WLAN Band Rejection for 3G/4G/5G Communications

Abstract: An eight element, compact Ultra Wideband– Multiple Input Multiple Output (UWB-MIMO) antenna capable of providing high data rates for future Fifth Generation (5G) terminal equipments along with the provision of necessary bandwidth for Third Generation (3G) and Fourth Generation (4G) communications that accomplishes band rejection from 4.85 to 6.35 GHz by deploying a Inductor Capacitor (LC) stub on the ground plane is presented. The incorporated stub also provides flexibility to reject any selected band as well as bandwidth control. The orthogonal placement of the printed monopoles permits polarization diversity and provides high isolation. In the proposed eight element UWB-MIMO/diversity antenna, monopole pair 3–4 are 180° mirrored transform of monopole pair 1–2 which lie on the opposite corners of a planar $50\times50$ mm2 substrate. Four additional monopoles are then placed perpendicularly to the same board leading to a total size of $50\times 50\times25$ mm3 only. The simulated results are validated by comparing the measurements of a fabricated prototype. It was concluded that the design meets the target specifications over the entire bandwidth of 2 to 12 GHz with a reflection coefficient better than −10 dB (except the rejected band), isolation more than 17 dB, low envelope correlation, low gain variation, stable radiation pattern, and strong rejection of the signals in the Wireless Local Area Network (WLAN) band. Overall, compact and reduced complexity of the proposed eight element architecture, strengthens its practical viability for the diversity applications in future 5G terminal equipments amongst other MIMO antennas designs present in the literature.

Isolation Improvement in UWB-MIMO Antenna System Using Slotted Stub

Abstract: Multiple-input multiple-output (MIMO) scheme refers to the technology where more than one antenna is used for transmitting and receiving the information packets. It enhances the channel capacity without more power. The available space in the modern compact devices is limited and MIMO antenna elements need to be placed closely. The closely spaced antennas undergo an undesirable coupling, which deteriorates the antenna parameters. In this paper, an ultra wide-band (UWB) MIMO antenna system with an improved isolation is presented. The system has a wide bandwidth range from 2–13.7 GHz. The antenna elements are closely placed with an edge to edge distance of 3 mm. In addition to the UWB attribute of the system, the mutual coupling between the antennas is reduced by using slotted stub. The isolation is improved and is below −20 dB within the whole operating range. By introducing the decoupling network, the key performance parameters of the antenna are not affected. The system is designed on an inexpensive and easily available FR-4 substrate. To better understand the working of the proposed system, the equivalent circuit model is also presented. To model the proposed system accurately, different radiating modes and inter-mode coupling is considered and modeled. The EM model, circuit model, and the measured results are in good agreement. Different key performance parameters of the system and the antenna element such as envelope correlation coefficient (ECC), diversity gain, channel capcity loss (CCL) gain, radiation patterns, surface currents, and scattering parameters are presented. State-of-the-art comparison with the recent literature shows that the proposed antenna has minimal dimensions, a large bandwidth, an adequate gain value and a high isolation. It is worth noticeable that the proposed antenna has high isolation even the patches has low edge-to-edge gap (3 mm). Based on its good performance and compact dimensions, the proposed antenna is a suitable choice for high throughput compact UWB transceivers.

A compact modified sierpinski carpet fractal UWB MIMO antenna with square-shaped funnel-like ground stub

Abstract: In this paper, a compact modified Sierpinski carpet fractal ultra-wideband (UWB) multiple-input-multiple-output (MIMO) antenna with a square-shaped funnel-like ground stub is presented and experimentally investigated. Miniaturization and wideband performance are achieved by using the proposed fractal structure. Iterated function system (IFS) method is used to design the proposed fractal structure. The self-similarity dimension of the proposed fractal structure is 1.72. The dimension of the proposed MIMO antenna is 24 × 30 mm2 and consists of two novels modified Sierpinski carpet fractal monopole-antenna elements. The impedance bandwidth of the presented antenna is 9.6 GHz (S11

Electronically Tunable Reflection Type Phase Shifters

Abstract: This brief presents a low loss reflection-type phase shifter (RTPS) using a single varactor diode as the load. A parallel combination of an open-circuited stub and a varactor loaded stub are used at the load terminal. This arrangement greatly improves the response of the phase shifter. A transmission line based analysis shows real part of the load plays an important role on both phase variation and insertion loss. Based on the analysis, design guidelines are provided for controlling maximum insertion loss of the phase shifter. A prototype phase shifter is fabricated at 10 GHz. Measurement results of the RTPS show a relative phase variation of 190° with a maximum insertion loss of 2 dB when varactor capacitance is varied over 0.1 pF–0.2 pF. Moreover, the return loss is always better than 20 dB over the entire tuning range of the RTPS.

Dual-Band Coaxial Filter and Diplexer Using Stub-Loaded Resonators

Abstract: This article presents a simple design of a coaxial dual-band cavity filter and diplexer using stub-loaded resonators (SLRs). Based on the resonance characteristics of a coaxial SLR, the first two resonant frequencies can be tuned over a wide range by adjusting their structural parameters. Controllable external quality factors can be acquired by using the modified tapping structure for the two designated passbands. A coupling window and a coupling pin are proposed to obtain the expected coupling coefficients in the two bands. To demonstrate this concept, a third-order dual-band bandpass filter and an eight-pole diplexer are designed and fabricated. The measured results agree well with the full-wave simulation results.

High-Performance Nano-Sensing and Slow-Light Applications Based on Tunable Multiple Fano Resonances and EIT-Like Effects in Coupled Plasmonic Resonator System

Abstract: A basic plasmonic system, consisting of a stub metal-insulator-metal (MIM) waveguide coupled with a ring resonator, is presented to realize Fano resonance and electromagnetically induced transparency-like (EIT-like) effect, which are numerically calculated by the finite element method (FEM). Meanwhile, the formation mechanism of Fano resonance is analyzed according to numerical simulations. Besides, the coupled mode theory (CMT) and the standing wave theory are used for explaining the Fano and EIT-like resonances phenomenon. Based on this system, an inner ring cavity is connected to the ring resonator by a slot and another ring cavity is later introduced under the stub resonator in order to constitute a new coupled plasmonic resonator system, providing quadruple Fano resonances and double EIT-like responses finally. In addition, the Fano and EIT-like resonances can be independently tuned by adjusting the structural parameters, which makes the design of highly integrated photonic circuits more flexible. The main contribution of this paper is that the proposed structure has a relatively good sensitivity of 1600 nm/RIU and an ultra-high FOM value of $1.2\times 10^{6}$ as a refractive index nanosensor. Moreover, it can serve as an all-optical switch with a high on/off extinction ratio of about 43 dB. Additionally, its maximum group delay time and group index are about 1.49 ps and 221, indicating that the proposed system has a pretty good slow light effect. Therefore, the proposed structures are believed to have significant applications in high-performance nanosensors, switches, slow light devices and nonlinear areas in highly integrated plasmonic devices.

Design and Investigation of Modern UWB-MIMO Antenna with Optimized Isolation.

Abstract: This paper proposes a compact, semi-circular shaped multiple input multiple output (MIMO) antenna design with high isolation and enhanced bandwidth for ultrawide band (UWB) applications. A decoupling stub is used for high isolation reaching up to −55 dB over the entire bandwidth. The proposed antenna is used for UWB as well as super wide band (SWB) applications. The overall size of the proposed antenna is 18 × 36 × 1.6 mm3. The | S 11 | and voltage standing wave ratio (VSWR) of the proposed antenna are less than −10 dB and 2, respectively, in the range of 3–40 GHz. The total impedance bandwidth of the proposed design is 37 GHz. The VSWR, | S 11 | , | S 22 | , | S 21 | , | S 12 | , gain, envelope correlation coefficient (ECC), radiation pattern, and various other characteristic parameters are discussed in detail. The proposed antenna is optimized and simulated in a computer simulation technology (CST) studio, and printed on a FR4 substrate.

A Multipurpose and Highly-Compact Plasmonic Filter Based on Metal-Insulator-Metal Waveguides

Abstract: A multipurpose and ultra-compact nanoplasmonic wavelength filter based on stub structure in a metal-insulator-metal (MIM) waveguide is suggested and numerically investigated. A novel approach of connecting two stepped-like apertures to both input and output ports is applied to form Fabry-Perot (FP) cavities, which enabled the structure to act as a dual band-pass filter at wavelengths 1310 nm and 1550 nm. It is shown that the variation in cavities’ length allows to realize a long-wavelength cutoff filter, and cutoff wavelength can be easily tuned by adjusting the length of the cavities. Furthermore, it is revealed that increasing the gap between the stepped-like apertures and the cavities provides a triple band-pass at telecom wavelengths, e.g., 1267.5 nm, 1414.19 nm, and 1644.7 nm. The tunable broadband high-pass wavelength filter is then achieved while the lengths of stepped-like apertures and stub resonators are set to be identical. Finally, a tunable nearly perfect absorber can be obtained by varying the width of stub resonators. Therefore, because of functionality, size, as well as efficiency the proposed plasmonic filter may greatly contribute to miniaturization of next generation of photonic integrated circuits (PICs), and find applications in on-chip integration and wavelength-division multiplexing (WDM) in optical communication systems.

Design of a compact LPF and a miniaturized Wilkinson power divider using aperiodic stubs with harmonic suppression for wireless applications

Abstract: In this paper a miniaturized low pass filter (LPF) with 2.5 GHz cut-off frequency and a novel compact, harmonics suppressed Wilkinson power divider (WPD) at 0.7 GHz is proposed. The proposed divider consists of two multi-stub LPFs and three open stubs at each port. The presented open stub at port one suppresses the second harmonic and other two open stubs at output ports, suppress the third harmonic. To suppress high order harmonics a novel 12 sections LPF based on aperiodic stub is proposed. This filter is designed to suppressed 4th to 15th harmonics. The cut off frequency of applied filter is 2.5 GHz, which creates 12 transmission zeros and suppresses corresponding 4th–15th harmonics of the proposed divider. The proposed WPD not only has perfect harmonics suppression, but also extremely decreases the circuit size. The overall size of the fabricated divider is only 0.116 λg × 0.044 λg, which shows more than 73% size reductions, compared to the 0.7 GHz conventional WPD.

High-Selectivity Single-Ended/Balanced DC-Block Filtering Impedance Transformer and Its Application on Power Amplifier

Abstract: In this article, a single-ended filtering impedance transformer with good frequency selectivity and high transforming ratio is proposed at first, comprising of the two cascaded coupled-line sections with a stub. Also, the balanced structure is expanded based on the differential- and common-mode analysis. The closed-form analytical equations and complete design procedures are provided in detailed. The working principle of the proposed single-ended impedance transformer is applied on the design of the filtering power amplifier (PA). Finally, a 3.3-3.6 GHz bandpass filtering PA with the measured drain efficiency of 62.3%-68.9% is designed, simulated, and fabricated, which displays the good filtering response and power amplification. Good agreement between the simulated and measured results is observed, thus demonstrating the validity of the impedance transformer and PA.

Characterization and Performance Measurement of Low RCS Wideband Circularly Polarized MIMO Antenna for Microwave Sensing Applications

Abstract: This article presents a low radar cross section (RCS), compact wideband, circularly polarized, multiple-input-multiple-output (MIMO) antenna for microwave sensing and measurement applications in S -and $C$ -bands. The proposed antenna consists of a wide slot and an I-shaped protruding stub in the ground plane of the antenna. A U-shaped strip is incorporated between two microstrip feed lines to achieve high isolation between antenna elements and a low envelope correlation coefficient (ECC), which results in the improved performance of the microwave sensing and measurement system. An array of the square slot is created in the ground plane of the antenna, which further enhances the isolation between the antenna elements and also reduces the RCS of the proposed antenna. The latter is fabricated with a low-cost FR-4 substrate using a precision printed circuit board milling machine. The 10-dB impedance bandwidth of the proposed antenna is 88% (3.7–9 GHz) with the isolation of greater than 15 dB. The 3-dB axial ratio bandwidth (ARBW) of the antenna is 3.7–5.7 GHz. The proposed antenna demonstrates significant RCS reduction in the frequency range of 10–24 GHz when compared with the same size metallic plate. The ECC, diversity gain (DG), and total active reflection coefficient (TARC) are also evaluated to justify the diversity performance of the proposed MIMO antenna.

A Broadband High-Efficiency RF Rectifier for Ambient RF Energy Harvesting

Abstract: In this letter, a compact broadband high-efficiency RF rectifier is presented for ambient RF energy harvesting (EH). A novel impedance matching network with an additional quarter-wavelength short-circuited stub was designed to achieve broadband impedance matching. After the branch was added, the parallel resonance point on track $S_{11}$ did not move, and the remaining points were compressed. The measurement results show that the proposed topology could realize a broadband high-efficiency rectifier for ambient RF EH, and the measured results were basically consistent with the simulation results. The measured efficiency is as high as 71.5% for an input power level of 8 dBm. A 1–2.4 GHz wide frequency band with an efficiency above 50% is achieved for an input power level of 5 dBm with a terminal load of 1.6 $\text{k}\Omega $ . Moreover, the circuit had wide dynamic input power characteristics, whose measured values remained above 50% with an input power of 3–14 dBm.

Compact Balanced Dual-Band BPFs Based on Short and Open Stub Loaded Resonators With Wide Common-Mode Suppression

Abstract: Two balanced microstrip dual-band bandpass filters (BPFs) based on short stub loaded resonator (SSLR) and open stub loaded resonator (OSLR) are presented in this brief, respectively. The center frequencies of the two differential-mode (DM) passbands can be controlled quasi-independently by adjusting the lengths of resonators. Moreover, a stepped impedance microstrip line etched with an interdigital coupling line is utilized to introduce a coupling between the two resonators, which generates two extra controlled transmission zeros (TZs) to obtain better selectivities. Furthermore, balanced microstrip/ slotline (MS) transition structures are employed as feed networks, which can suppress common-mode (CM) inherently while the DM responses are not affected, thereby the design procedure can be simplified significantly. In order to demonstrate the theoretical design, two balanced dual-band BPFs were designed and fabricated. The simulated responses are compared with the measured ones and a good agreement is obtained.

Compact Beam-Scanning Flat Array Based on Substrate-Integrated Waveguide

Abstract: A compact beam-scanning flat antenna array with high gain based on the substrate- integrated waveguide (SIW) is presented in this article. The radiation elements are the continuous transverse stub (CTS) constructed by SIW, which are arrayed on the substrate. The SIW-CTS array has a 4 dB higher gain than the traditional CTS array with the metal parallel plate waveguide and the theoretical explanation is analyzed. A new compact corporate-feed network consisting of an SIW-horn and a flat lens is also proposed. The flat lens could convert the cylindrical wavefront generated by the feed probe and the SIW-horn to a planar wavefront for feeding the CTS array. The Taylor distribution of the feed level made the array has a low sidelobe and high gain. The beam scanning of the array could be realized by simply moving the small SIW-horn along the line across the focal point. An eight-element array is designed, simulated, and fabricated to verify the design. The measured results show that the scanning range is from −35° to 35° with the highest gain of being 20.6 dBi and the sidelobe level of −25.2 dB at the broadside.

Ultra-Compact Reconfigurable Band Reject UWB MIMO Antenna with Four Radiators

Abstract: A compact reconfigurable UWB MIMO antenna with four radiators that accomplish on-demand band rejection from 4.9 to 6.3 GHz is presented. An LC stub is connected to the ground plane by activating the PIN diode for each radiator. Two radiators are placed perpendicular to each other to exploit the polarization diversity on a compact 25 × 50 mm 2 FR4 laminate. Two additional radiators are then fixed obliquely on the same laminate (without increasing size) in angular configuration at ±45 ∘ perpendicular to the first two planar radiators still exploiting polarization diversity. The design is validated by prototyping and comparing the results with the simulated ones. On demand band rejection through the use of PIN diodes, wide impedance matching (2–12 GHz), high isolation amongst the radiators, compactness achieved by angular placement of the radiators, low gain variation over the entire bandwidth, band rejection control achieved by adjusting the gap between stub and ground plane, and low TARC values makes the proposed design very suitable for commercial handheld devices (i.e., Huawei E5785 and Netgear 815S housings). The proposed configuration of the UWB MIMO radiators has been investigated first time as per authors’ knowledge.

An Ultra-Wideband Rectangular Dielectric Resonator Antenna With MIMO Configuration

Abstract: A Coplanar waveguide (CPW) fed multi-permittivity and stair shaped dual rectangular dielectric resonator antenna (RDRA) has been designed for ultra-wideband (UWB) applications in multiple-input multiple-output (MIMO) configuration. Isolation improvement has been obtained by means of modified CPW feeding and a metallic diagonal stub in the proposed structure. The simulated results have been validated by prototype designing and performing measurements. The electrical size of the proposed antenna configuration is $1.12\lambda _{0}\times 1.12\lambda _{0}\times 0.25\lambda _{0}$ . The measured input impedance bandwidth of the antenna is 153.6% (1.6-12.2 GHz) with a minimum of 25 dB isolation between the radiators in the operating band. Measured results illustrate the satisfactory performance of proposed UWB MIMO antenna with a low envelope correlation coefficient and low mutual coupling throughout the desired frequency range.