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In this paper, a four port MIMO antenna of compact split ring resonator (SRR) type with high degree of isolation among four ports on the antenna has been proposed for MIMO multiband applications. It is Tribands which operate at frequencies 1.44 GHz (−11 dB), 2.3GHz(−10 dB) and 4.2 GHz (−245 dB) respectively. This proposed MIMO antenna is designed with meander line for better gain and Split Ring Resonator (SRR) in the form of ring for high isolation between the antenna elements. A loaded stub is used to achieve the resonant frequency. The proposed MIMO antenna was simulated with IE3D EM software by Mentor graphics and the features such as impedance view, lower return loss, gain, radiation pattern and VSWR, etc are measured. The proposed antenna has better gain and provides higher isolation between multiple antenna elements.

In memory devices, such as solid-state drive, multitopology is used for interfaces where multiple memory packages are connected to a controller using a branched transmission line. Impedance mismatching caused by the branches and unwanted reflection from deactivated packages inevitably degrades signal quality, limiting the data rate of the interface. In this article, a simple stub equalizer is proposed to improve the data rate of the memory interface. An open-ended stub is placed between a transmitter and a receiver, and the length, impedance, and location of the stub line are determined to properly cancel the reflection from other branches. Parameters are optimized based on the peak distortion analysis and an exhaustive search considering both read and write modes. The improvements are validated through eye-diagram simulations.

In this paper a dual E–shaped patch (ESP) antenna is proposed to enhance the wider impedance bandwidth to be use for wireless communications in 5G applications. The proposed dual ESP antenna performance analysis is carried out with stub in this work. The proposed ESP antenna with stub achieving reflection coefficient below -10 dB for obtained multiple resonant bands. The dual ESP antenna operates at 5.7 GHz,10.1 GHz,15.1 GHz,19.4 GHz and 22.4 GHz obtain reflection coefficient of −44.32 dB, −27.43 dB, −17.0 dB, −50.85 dB and −18.07 dB respectively. The proposed antenna with stub achieves impedance bandwidth of (4.28 GHz–24.06 GHz) with 139.37% enhancement resonate at 19.77 GHz operating frequency. The radiation patterns, current distributions and gain plots are observed at five resonant bands. The simulated results are matched well with the measured results.

In recent days, the growth of wireless communication systems has greatly influenced the communication sectors. Especially, the technological advancements made in the UWB filters play a significant role in redesigning the UWB signals. In this paper, we have proposed a modified Defected Ground Structure (DGS) for Microstrip Ultra-wideband filter. The aim of the study is to design an efficient and lightweight UWB filter design for efficient communication systems. Thus, a different UWB filter is designed with permissible frequency range which improves the performance of the stopband. In this work, the DGS, interdigital, SIR & Shunt stub are employed. Then, a filter prototype is fabricated and measured. The results show that the modified DGS achieves 104.3% Bandwidth, less than 15 dB Loss of return with a frequency of 6.9 GHz for 0.25 λ0 × 0.16 λ0 size. The proposed design has improved the performance of the stopband in the aspects of return loss and the insertion loss.

In this paper, a coplanar waveguide-fed ultra-wideband-multiple-input and multiple-output (UWB-MIMO) antenna with a novel stub for isolation has been presented. The dimensions of the proposed antenna are 18 × 22 × 1.6 mm3. The proposed antenna is design on an FR4 substrate and simulated in CST studio. The |S11| of the presented MIMO antenna is less than −10 dB between 2.8 and 13 GHz with an impedance bandwidth of 10.2 GHz. The envelope correlation coefficient (ECC) is less than 0.007 and diversity gain (DG) is greater than 9.97 dB. The proposed UWB-MIMO antenna is analyzed in terms of isolation, reflection coefficient, current distribution, ECC, DG, peak gain, multiplexing efficiency, and radiation pattern.

Due to the progression growth of multiservice wireless communication systems in a single device, multiband bandpass filter has attract a great attention to the end user. Therefore, multiband bandpass filter is a crucial component in the multiband transceivers systems which can support multiple services in one device. This paper presents a design of dual-band bandpass filter at 2.4 GHz and 3.5 GHz for WLAN and WiMAX applications. Firstly, the wideband bandpass filter is designed at a center frequency of 3 GHz based on quarter-wavelength short circuited stub. Three types of defected microstrip structure (DMS) are implemented to produce a wide notch band, which are T-inversed shape, C-shape, and U- Shape. Based on the performance comparisons, U-shaped DMS is selected to be integrated with the bandpass filter. The designed filter achieved two passbands centered at 2.51 GHz and 3.59 GHz with 3 dB bandwidth of 15.94 % and 15.86 %. The proposed design is very useful for wireless communication systems and its applications such as WLAN and WiMAX

A MIMO antenna having circular patch with CPW feeding is proposed in this paper. Design, Simulation, Fabrication and testing of MIMO antenna with different band notching characteristics are proposed in this paper. The designed antennas are suitable for portable UWB applications. UWB is the most promising technology which provides high data rate with in short range. In 2002 Federal Communication Commission (FCC) has approved a frequency band of 3.1–10.6 GHz for unlicensed applications. Within the band of UWB some of the wireless Communication bands with different frequencies are also operating. So to avoid interference, band dispensation characteristics are proposed. In this paper single dual, triple and quad band notch MIMO antennas are designed, simulated and tested and their results are reported. Elimination of interference with existing wireless bands like WiMAX, WLAN, X—Band Satellite Communication System and ITU is the prime focus of the paper. Concentric rings with rectangular split bricks are placed on the patch to eliminate the interference with the existing bands. Different antennas are designed and simulated using CST microwave studio software and the antenna parameters like Return losses (S11), Gain, VSWR, Radiation patterns and Correlation Coefficient are measured. Quad band notch antenna is fabricated using RT/Duroid 5880 substrate material with height 1.57 mm. To get better Isolation the antennas are placed vertically and a stub is placed in between the antennas. The quad band antenna able to notch WiMAX, WLAN, X—band and ITU band and port Isolation (S12) is very good and envelope correlation is below 0.001 in UWB frequency spectrum.

The signal integrity of dual-rank LPDDR5 interface is challenged by reflections from the stub of the inactive rank within the redistribution layer (RDL). These reflections arrive at the active rank within the unit-interval of the data-rate and distort not only the post-cursor but also the pre-cursor of the signal that the decision feedback equalizer (DFE) cannot remove. We introduce a differentiating receiver that restores data through edge information to eliminate the reflective distortions, including the pre-cursor, and a transition-detecting DFE to address remaining inter-symbol interference. A prototype receiver, fabricated in a 65 nm CMOS process, eliminates pre-cursor distortion with a reflection flight time of 50 ps and 70 ps, at 8 Gb/s and 6.4 Gb/s, resulting in a wide horizontal margin at a bit-error-rate of 10−12. The energy efficiency is 0.80 pJ/bit at 8 Gb/s.

This paper presents improved quad-mode resonators based on the open/short-end load of the center stub, which introduces the self-coupled structure. Compared with the traditional stub-loaded stepped impedance resonator (SLSIR), the proposed quad-mode resonators can significantly reduce the circuit size and further increase the design freedom. First of all, a comprehensive theoretical analysis is performed to infer the resonant characteristics of the proposed resonator. Then, two design prototypes based on different center loads of the resonator were demonstrated to verify the feasibility of the design method. First, a prototype of a wideband high temperature superconducting (HTS) filter with an FBW of 89% is proposed, whose center frequency (CF) can be flexibly controlled. Next, a quad-band HTS filter using different central stub load is proposed, which centered at 1.20, 2.52, 3.51, 4.44 GHz with the 3-dB FBW of 4.8%, 3.96%, 3.97% and 2.2%, respectively. The internal and external coupling mechanisms are also carefully studied to meet the specified requirements. The two prototypes proposed in this paper both have the advantages of compact size, ultra-low insertion loss and steep suppressed skirts. In addition, the measured results are in good agreement with the EM full-wave simulated results.

An electrically small ultra-wideband antenna for modern compact devices is presented in this paper. The antenna is constructed using a low-cost FR4 substrate, where etching slot and stub loading techniques are utilized to achieve miniaturization. The antenna comprises of simple geometrical structure with an overall size of 0.13 λo × 0.19 λo × 0.02 λo (λo is the free-space wavelength at 3.5 GHz). A sample prototype was fabricated and tested to validate various performance parameters of the antenna. The antenna has measured 10 dB impedance bandwidth ranging from 3.55–12.16 GHz with a stable gain having a maximum value of 4.52 dBi. The performance comparison with state-of-the-art works shows that the proposed antenna offers the advantages of miniaturized size, simple geometry along with competitive bandwidth and stable radiation characteristics.

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.

In the digital communication system, waveform distortion due to reflection of the multidrop transmission line is one of the main issues for high-speed signal transmission. Although many approaches to reducing the reflection, such as asymmetrical power splitter, stub series terminated logic, and the segmental transmission line have been used in the past, the drawbacks of amplitude loss at the receivers, or high power consumption due to excessively low impedance design are still problems. In this article, we introduce a new method, “reflection compensation line (RCL),” which is constructed in isometric length of main bus segments and stub lines. The method using the RCL intentionally generates reflections to cancel the distortion and restore the ideal waveform at the receivers. In order to reduce the waveform distortion effectively, an optimal set of transmission parameters is determined by means of evolutionary gradient search. The performance of the proposed method especially at the stub lines of both ends of the main bus line is confirmed using the SPICE simulation, and its applicability to practical systems is also discussed.

This letter describes the design, simulation, and measurement process of a series radio frequency (RF) rectifier at the 2.4 GHz ISM band, composed of a distributed filter with radial stub elements. The proposal is to reduce the first- and second-order harmonic components that are generated by the diode nonlinearities at the rectifier output. The efficiency and output voltage are presented according to load values ranging from 1 to $10 k\Omega $ . These figures of merits are obtained with a new methodology, using an automatized measuring setup, which describes in detail the behavior and nuances of the circuit according to the frequency and input power through experimental level curves. The proposed RF rectifier prototype reaches over 20% efficiency for input power levels over −20 dBm for the lower load values, showing a satisfactory performance in comparison with other proposals for low-power applications.

The design and analysis of a T-Stub U-Slot Frequency Reconfigurable Notch band antenna is considered in the present work using Coplanar Waveguide feed network for an efficient power transfer to improve the bandwidth characteristics of the antenna. The designed antenna has a dimension of 24X21X1.6 mm with FR4 substrate having a permittivity of 4.4. The proposed antenna consists of a T-Stub and U-Slots which are used to enhance the performance characteristics of the antenna. The reconfigurability is achieved by placing PIN diodes at T-Stub and U-Slots of the antenna design. The designed antenna is more suitable for WLAN, Wi-Fi, LTE and Bluetooth applications. Simulation results are obtained using CST tool and the same are presented at the end.

In this paper, a wideband resistance compression network (WRCN) based on the transmission line is proposed. It consists of three impedance transform networks formed by radial-line stub and shorted-...

In this study, a compact configuration of frequency reconfigurable filtenna, designed by integrating a bandpass filter and with a monopole radiator, is demonstrated for achieving high-frequency selectivity along with compact size. The proposed filtenna can be efficiently tuned between ultra-wideband (UWB) and C-band states of operation. A bandpass filter, based on rectangular stepped impedance stub loaded multiple-mode resonator (MMR), is embedded to an elliptical monopole radiator to construct the filtenna circuit. The filtenna design approach leaves out the necessity of cascading an additional 50 Ω microstrip feed line in between the antenna and filter elements which makes the system more compact. The designed filtenna occupies 3.6–10.6 GHz band in its UWB state of operation and 3.63–4.70 GHz band in its C-band state of operation, respectively. The UWB operating state is intended for spectrum sensing application whereas the C-band operating state can be implemented for communication in a cognitive radio environment. The shifting between two operating states is controlled by appropriately switching the PIN diodes. An average peak gain of 2 dBi is observed within the passband. The overall size of the filtenna is optimised to 1.35 λ 0 × 0.96 λ 0 × 0.04 λ 0 ( λ 0 is calculated at 6.85 GHz). For validation purpose, the filtenna prototype is fabricated and characterised. A very close agreement is achieved with the suggested configuration.

In this proposed research article, four-port dual notched bands multiple-input-multiple-output (MIMO) antenna configuration is proposed and is experimentally investigated by fabricating prototype. Initially, a single element is fabricated which is converted to 2 × 2 MIMO configuration and finally to 4 × 4 MIMO configuration. The proposed MIMO antenna is designed to cover impedance bandwidth of 3.15–11.36 GHz and hence is useful in applications for ultrawideband and X-Band applications. Two interfering bands, WiMAX (3.30–4.05 GHz) and WLAN (4.90–5.99 GHz) are eliminated by using an inverted T-shaped stub and C-shaped slot on the radiating patch of the MIMO antenna. The proposed MIMO antenna offers good diversity performance with envelope correlation coefficient 9.95 dB and total active reflection coefficient ≤ 20 dB in the entire operating band. Also, antenna gain is stable in the entire operating band except in interfering bands with a maximum radiation efficiency of more than 80% and stable radiation pattern. All the above said features make the proposed antenna suitable for high-speed wireless network applications.

The development of a millimeter-wave unbalanced frequency tripler based on the nonlinear characteristics of planar Schottky varactors is presented. The entire module is designed by hybrid integration. A frequency multiplier circuit model was established to reflect the influence of diode parameters and the impedance matching on the multiplier in different frequency bands. The effect of junction imbalance on the output power of the frequency multiplier was investigated and the multiplier was improved based on the basic design. The addition of a cut microstrip stub in the improved diode unit reduced the impact of a power imbalance on frequency multiplier performance. The characteristics of the multiplier circuit were analyzed by the full-wave electromagnetic simulation of the three-dimensional structure and the harmonic balance simulation of the circuit. Test results showed that the peak output power of the improved frequency tripler was 12.6 mW at 277 GHz with an input power of 200 mW, an effective 12% improvement over the basic design.

Generally, a conventional voltage doubler circuit possesses a large variation of its input impedance over the bandwidth, which results in limited bandwidth and low RF-dc conversion efficiency. A basic aspect for designing wideband voltage doubler rectifiers is the use of complex matching circuits to achieve decade and octave impedance and RF-dc conversion efficiency bandwidths. Still, the reported techniques till now have been accompanied by a large fluctuation of the RF-dc conversion efficiency over the operating bandwidth. In this paper, we propose a novel rectification circuit with minimal inter-stage matching that consists of a single short-circuit stub and a virtual battery, which contributes negligible losses and overcomes these existing problems. Consequently, the proposed rectifier circuit achieves a diode physical-limit-bandwidth efficient rectification. In other words, the rectification bandwidth, as well as the peak efficiency, are controlled by the length of the stub and the physical limitation of the diodes.

This article presents the design scheme of a wideband Wilkinson Power Divider (WPD) with two-stage architecture utilizing quarter-wave transmission lines and short-circuit stubs. The bandwidth of the proposed WPD is flexible and can be controlled using the design parameters. The proposed design achieves excellent isolation between output ports in addition good in-band performance. The analysis of the proposed circuit results in a simplified transfer function which is then equated with a standard band-pass transfer function to determine the parameters of transmission lines, stub’s impedances, and the value of the isolation resistors. Furthermore, it is also demonstrated that a simple alteration in the proposed circuit enables the design of a wideband DC isolated WPD that maintains a good in-band and isolation performance. A number of case studies have been included to highlight the flexibility of the proposed design. Two distinct prototypes are developed on different boards to demonstrate the wideband performance of the proposed design. An excellent agreement between the experimental and measured results for both the designs over a wide band including very good isolation between ports validate the proposed design.

Two-port multi-input multi-output (MIMO) antenna for a 5G application is presented in this paper. The presented made of 2 monopole elements with an overall size of 11 x 4.5 mm2. To reduce the effect of one antenna element to another element, an optimized study has been considered. To reduce isolation between the ports of the designed MIMO, a stub has been put into the ground plane. The presented MIMO for 5G wireless application has been carried out using HFSS software. The S 11 value of deigned MIMO antenna obtained at 26 GHz resonance frequency and bandwidth of 4.3 GHz (from 24.0 GHz to 28.3 GHz) and isolation is below -27 dB. The MIMO performance of the presented MIMO antenna gives good results such as impedance bandwidth, radiation pattern, isolation, and gain. The presented MIMO antenna shows a high-quality applicant for 5G mm-wave application.

This paper proposes a compact, Fork Shaped stub to enhance the isolation between 2×2 MIMO antenna in Ultra- Wide Band. The overall size of the antenna is 28×20×1.6mm3. The proposed antenna was designed with Multiple-input -multiple-output (MIMO) and operated at a frequency of 5.1GHz for Wireless Communication. This MIMO having two antenna elements placed side by side to each other. A Fork shaped stub is placed in between two antenna elements to reduce mutual coupling. This Stub reduces the electromagnetic interferences in between MIMO elements and enhances the isolation. The proposed antenna was designed with Characteristic mode analysis for a better understanding of physical insight of structure. The dominant mode of the proposed antenna can find out easily with Characteristic Mode Analysis without applying the feed and excitation. The proposed antenna maintain good isolation more than 22dB entire UWB spectrum and Envelop correlation coefficient is (ECC)

Self-interference cancellation (SIC) is critical for In-Band Full-Duplexing (IBFD) systems, which facilitate doubling of the spectrum efficiency [1] . Propagation-level SIC methods are especially attractive as they ease the required dynamic range of the receiver (Rx) hardware. While the multi-antenna solutions increase the form factor of transmitter (Tx) – Rx system, the single antenna configurations typically employ expensive and bulky circulators. Polarization-based isolation has been previously shown for a two-antenna system by employing an active-component loaded stub-resonator [2] . However, the design requires multiple-layers of thick substrate to provide both the matching and directivity to the antennas. In addition, the reflections from the stub resonator interfere with the Tx antenna patterns and the distortions produced by the active component propagate through the Rx chain, degrading its sensitivity.

This paper presents a kind of Ku-band filtering power divider(FPD) design with thin-film integrated passive device(IPD) technology and improved isolation structure. The Thin-Film IPD technology can well meet the greater requirements of processing accuracy and circuit layout in higher frequency band. Fourth-order quasi-elliptic filter is employed to realize good passband selectivity and out-of-band rejection. A compound structure including a GaAs-based resistor and an inductive stub is adopted to achieve good in-band isolation and matching. Phase difference can be changed by selecting different feeding point. Finally, two FPDs operating at 16 GHz are designed and adjusted.

As more components are integrated into a denser area in electronic devices, the complexity of routing increases. A routing design resulting from routing tools may pass all design rule checks, but it can also result in signal integrity problems, which affect the performance of the entire link path, often not realized until the layout stage. In this paper, such designs are analyzed for their unintentional resonances in the insertion loss and the crosstalk of the signals. As an example, an unintentional power plane stub created by trace routing revisions adjacent to the signal trace behaves as a quarter-wavelength resonant structure. To avoid such unintentional resonances in high-speed signals, trace routing should be carefully designed and design rule checks must be improved to detect and warn the users of such potential signal integrity hazards.

A wideband filtering phase shifter is proposed using a cascaded single line and coupled line as a shunt stub of the centre-coupled line. Such kind of a shunt stub provides the possibility to achieve wideband impedance matching, wideband phase shift, and multiple controllable transmission zeros (TZs) at the same time. The coupling between the shunt stubs of the practical layout can generate extra TZs and enhance the frequency selectivity. Compared with the state-of-the-art designs, the proposed one has wider bandwidth, more TZs and medium size, and the former cannot juggle bandwidth and size. Two prototypes at 1.76 GHz are designed with the relative operating bandwidth for 45°±3° (90°±4.2°) phase shift of 75% (76%), five TZs and the minimum return loss of 14.7 dB.

An 8-element dual-band multiple-input–multiple-output (MIMO) antenna operating in the 5G New Radio band n77 (3300–4200 MHz) and 5 GHz band (4800–5000 MHz) in mobile handsets is presented. The 8-element MIMO antenna is formed by employing four sets of dual-antenna arrays (DAAs) that are symmetrically printed along the two long side–edge frames of the smartphone. Each DAA is composed of two double-branch monopoles and a T-shaped decoupling stub, in which good mutual coupling reduction can be realized via the decoupling structures. Furthermore, the decoupling structures can also aid in improving the impedance matching of the array units for achieving wideband operation.

UWB systems provide a distinctive solution for short-range wireless communication due to large bandwidth and low power consumption in transmission and reception. However, for these systems, designing an antenna with optimal characteristics is a major challenge, because it needs to avoid interference with existing narrowband systems (e.g., WLAN, Wi-MAX, HIPERLAN, ITU-R, etc.) in the UWB spectrum. To achieve this, different techniques (e.g., Slot, parasitic element and stub loading, Using fractals, metamaterials and electromagnetic band gap (EBG) structures) have been reported in the literature and this paper provides a comprehensive review of the mentioned techniques for achieving band notch characteristics in UWB antennas. Moreover, the challenges, future perspectives, simulated and measured results, different notched bands and their applications are also discussed in this paper to make it useful for future research.

Signal distortion, called ringing, in a controller area network with flexible data rate (CAN-FD) causes asymmetry in propagation delay throughout a network, which is dependent on its physical bus design and becomes a critical issue in limiting the data rate. Thus, in this paper, the bus structure of a CAN-FD is investigated and a transfer function of ringing is modeled by considering the physical bus configuration and features of a controller area network transceiver. The effects of the main parameters of the physical bus, such as the stub line length and number of stub lines connected to a joint connector, are then quantitatively analyzed using the presented model. When a practical bus structure is considered, additional signal distortion owing to a neighboring connector in a physical bus is modeled and analyzed. These analytical results are confirmed experimentally. Their comparison shows that the presented model-based analysis can closely approximate the size and time response of ringing and the extent of bit time distortion. The presented model-based analysis facilitates reliable communication performance by estimating the ringing and resulting asymmetry of the propagation delay for a given physical bus design and, if necessary, adjusting the design.

Purpose This paper aims to analyze the negative impact of surface mount (SMT) pad and imperfect via structure such as stub, pad, non-functional pad (NFP) and anti-pad on the signal integrity at 40 Gbps transmission on printed circuit board (PCB) due to impedance mismatch or discontinuity. The optimized modeling of via and SMT structures is performed to achieve minimal impedance mismatch and insertion loss less than 10 dB for six-inch full path transmission line between transmitter and receiver on PCB at Nyquist frequency 20 GHz. Design/methodology/approach This work is split into two phases. The first phase involves optimization of via and SMT structures in three-dimensional electromagnetic (3DEM) simulation using Hyperlynx Via Wizard and Keysight EMPro software, respectively, followed by analysis of time domain reflectometry (TDR) and insertion loss (Sdd21). Whereas, in the second phase, full path hybrid mode simulation involving vias for signal layer transition, a 6-inch PCB channel and SMT pads is performed using Keysight ADS software to observe the TDR, Sdd21 and eye diagram at 40 Gbps transmission. Findings Imperfect via and SMT structures have a negative effect on signal reflection and attenuation. The optimized via and SMT minimizes the impedance mismatch by 81 per cent and insertion loss by 4.5 dB, ultimately enlarging the eye diagram opening to achieve minimal data loss at receiver with 40 Gbps transmission. Originality/value The results of original empirical research work on signal integrity analysis that optimizes the PCB channel design to achieve 40 Gbps signal transmission are presented in this study. It serves as a reference guide for high-speed PCB layout design.

In this paper, an analytic design method for a frequency- and bandwidth-tunable absorptive bandpass filter is introduced. The presented design method relies on the transformation from the normalized absorptive low-pass filter prototype to a bandpass filter structure with parallel resonators and admittance inverters. The inverter values for producing a predefined frequency response are given in closed-form expressions so that a filter design needs no heuristic approach and can be carried out in an analytic manner. This work also presents a new tunable stub resonator structure capable of changing not only its resonant frequency but also the slope parameter. As the slope parameter can be adjusted, it is allowed to use static inverters in designing a filter whose bandwidth can be tuned. For demonstrating our design method for a reconfigurable absorptive bandpass filter, a third-order filter having the target to have the frequency tuning range from 1.35 to 1.65 GHz and the bandwidth tuning range from 5% to 10% has been designed and measured.

Reconfigurable antenna array has received a lot of attention in present-day wireless communication systems. In this study, a simple design of a four-element circularly polarised dual-frequency reconfigurable microstrip patch antenna array for millimetre-wave applications is proposed. The sequentially rotated series-parallel stub approach is employed in the feeding network design to provide symmetrical array elements positioning, and bringing about a good axial ratio of polarisation. Additionally, a matching branch per element is employed to generate spatial flexibility for element positioning and good impedance matching. Furthermore, due to high-cost constraints of Ka-band RF switches (such as PE42524 SPDT), switches are considered as transmission lines, and are placed within the fractal slots of each elements to reconfigure the frequency. The proposed array operates in two switching states: ON and OFF. Hence, it allows dual-frequency reconfigurability of 27 and 35 GHz for the ON and OFF states, respectively. A full array prototype was then fabricated on a Rogers R5880 substrate and tested in an anechoic chamber. Simulation and measurement results corroborate quite well in general. Patch antenna array gives much better result characterised by reconfigurable behaviour with associated return loss, radiation pattern characteristics, and

In this study, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with reconfigurable band notch characteristics is presented. The key feature of the antenna is its novel dual-band notch technique which blocks worldwide interoperability for microwave access or wireless local area network band interference. The UWB-MIMO property is achieved by two square monopoles separated by grounded multi-branch T-shaped stub. The reconfigurable dual-band notch operation is performed by PIN diodes integrated in a parasitic resonant structure in the ground plane. The antenna has a compact size of 40 × 20 mm 2 , with the operating frequency band of 3-11 GHz, where port isolation is better than 15 dB. The MIMO performance is ensured by calculating envelope correlation coefficient for the isotropic, indoor and outdoor environment.

Isolation and bandwidth are the two important performance parameters of the multiple-input-multiple-output (MIMO) antenna. A small footprint of an antenna with enhanced isolation and extended bandwidth is highly desirable for space-limited UWB applications. In this paper, we present a compact and computationally optimized MIMO antenna for UWB applications. The proposed antenna consists of two micro-strip-fed semicircular radiating elements. The inverted prism-shaped ground stub is used to enhance isolation. A truncated-shaped partial ground plane with two ground slots is used for impedance matching over the extended UWB. The circular monopole radiating elements of the reference antenna (RA) are converted into semicircular radiating elements for efficient utilization of the available space. The initial design parameters are obtained from the RA. In the next step, the initial design parameters are optimized by a fast and accurate surrogate-assisted optimization model. Using the optimized design parameters, the final design of the antenna is simulated using a computer simulation tool. The prototype of the antenna is fabricated on a Roger substrate (substrate height ‘h’ = 0.8 mm) with a dielectric constant of 3. The manufactured prototype with the size of 31 × 18 mm2 is experimentally evaluated and validated using vector network analyser and anechoic chamber. The proposed MIMO antenna provides extended ultra-wide impedance bandwidth of 3–25 GHz (fractional bandwidth 157%), enhanced isolation S21 ≤ − 27 dB envelope correlation coefficient (ECC = 0.002), good pattern diversity, and constant group delay. Finally, the obtained results are compared with the existing literature.

This paper presents an effective design method of chipless RFID tags. With $n$ -bit first- and second-order chipless tags’ equivalent circuits proposed based on filter theory, the relationship between bits and frequency bands of tags is characterized by formulas. Combining with microstrip-line theory, the first-order chipless tag with single quarter-wave open-circuited (O.C.) shunt stub units, and second-order chipless tag with parallel pairs of quarter-wave O.C. shunt stubs are designed, respectively. The pros and cons for each type of the chipless tag are discussed. Two types of 5-bit chipless tag examples are given with good consistent simulated and measured results. In addition, for the second-order chipless tag, we propose a miniaturization scheme, enhancing the antidamage ability simultaneously. Damage test shows that the second-order chipless tag has the good antidamage ability, especially for the miniaturized tag. Finally, the bit extension by the formulaic method is discussed, emphasizing a promising practicability.

In this work, a new design of wide-band multiple-input multiple-output (MIMO) antenna with improved isolation and dual-band rejection is proposed for wireless systems operating over the entire ultra-wide-band (UWB), X-band, and Ku-band (3–18 GHz). The proposed four-element UWB-MIMO antenna is fabricated on Rogers RT/Duroid-5880 substrate with dimension of 73 × 73 × 0.79 mm 3 . It achieves high isolation (>20 dB) between antenna elements without using any decoupling structures. In order to prevent interference problems from nearby WiMAX (3.3–3.8 GHz) and WLAN (5.1–5.8 GHz) systems, a C-shaped stub is embedded in the radiating patch and a pair of U-shaped parasitic strips is inserted beside the feed line in the single element design. The effectiveness of the proposed design is demonstrated by investigating measurement and simulation results, and comparing them with other existing designs. The results show that the proposed design has an input reflection coefficient

A novel reconfigurable dual-bandpass filter with independently controlled center frequencies and fixed bandwidths is presented. It was designed to be integrated as a radio frequency anti-aliasing filter in a reconfigurable multi-bandpass sampling global navigation satellite system (GNSS) receiver. The center frequency tuning ranges are 1190–1210 MHz and 1560–1590 MHz in the lower and the upper L-bands, respectively, with a fixed bandwidths of 35 MHz. Varactor tuning technology associated with open loop stub loaded resonator microstrip topology were investigated to achieve these goals. The proposed dual-bandpass filter design showed the agility to independently control the center frequencies in the two L-bands and to deactivate one of the passbands. Furthermore, it shows enough flexibility to adapt to the deployment of new GNSS standards specifications. It exhibits on all the tuning ranges an insertion and a return losses of less than 4.5 dB and more than 10 dB, respectively.

A bandpass filter has been presented in this paper with its design, which has been substantiated by its analysis followed by confirmed and authentic results. The authors have used a simple approach and method to realize the three transmission poles and two transmission zeroes for application in the Ku-band. The resonant frequency is achieved by the implementation of half-circular-shape (HCS) patch and stubs as well. At first, the 50-Ohms input impedance is provided by the use of the microstrip transition. Apart from this, four open stubs, along with two HCSs patches, are executed on the radiation of the structure. The merits of HCS patch and stubs is to produce the resonant frequency. Moreover, a stub is placed on each side of the port. The length of each stub that is placed on either side of the port is equivalent to half of the guided wavelength. Additionally, to eliminate the unwanted noise and improve the fractional bandwidth, the feed-line and stub gap plays a primary role in the design. The designed filter can be used for Ku-band applications.

The recent developments in microwave systems, put high requirements to antenna arrays for RFID and radar applications, in terms of pattern shape and side lobe specs. The presented paper discusses an inexpensive approach for amplitude distribution control of aperture-coupled microstrip patch antenna, as a building block of more complex array systems.

Ultra−WideBand (UWB) technology was approved by the Federal Communications Commission (FCC) in February 2002 (FCC, 2002). According to the FCC regulations, the frequency band from 3.1 to 10.6 GHz can be used for short−range and high speed wireless communications systems. This recent allocation of a very wide spectrum of frequencies for the devices uses, with effective isotropic radiated power (EIRP) less than 41dBm/MHz has presented numerous exciting opportunities and challenges for antenna designers. UWB antennas should be effective in transmitting, compact, non dispersive, and have a good wide impedance bandwidth properties, these features are desirable for both indoor and outdoor hand−held UWB applications. In practical UWB applications, microstrip antennas that can be directly printed onto printed circuit boards (PCBs) are the most promising candidates. Such a PCB antenna has a low profile, a low manufacturing cost and can easily be integrated with other parts of monolithic microwave integrate circuit (MMIC) for a transceiver or any other UWB system. To satisfy such requirements, various types of planar antennas have been developed for UWB communications over the last few years. Also, several bandwidth enhancement techniques have been reported, to improve the impedance bandwidth of these antennas. Microstrip UWB antennas are usually constructed by etching a radiator onto the dielectric substrate of a piece of the PCB and a partial ground plane onto the opposite side if the antenna is fed by microstrip transmission line or on the same side in the case of coplanar waveguide (CPW) feeding. In the literature, many different microstrip UWB antennas with circular, elliptical, triangular, rectangular, hexagonal, and so on patches are currently being considered for UWB applications. This chapter presents an overview of UWB antennas design an characterization, some novel designs were investigated and presented. The first class of studied UWB antennas is microstrip monopole antennas including the microstrip/CPW−fed modified − elliptical monopole antennas. The second class is for UWB slot antennas, where a novel stepped inverted cone slot antenna with different stub shapes is proposed for UWB applications. In the third class a notched band UWB antenna is presented; the proposed UWB have been developed to notch−band UWB antenna by inserting a U−shape slot into patch. The advantage of this approach is that the stop−band filter (slot) can directly integrated in antenna structure. The study includes detailed parametric analysis of the antennas performances with relation to the desirable properties for UWB antennas. 15

This paper presents a development of a compact ultra-wideband (UWB) slot antenna using stair-step impedance technique with a pentangular stub for 5G application. The proposed antenna is miniaturized and fabricated on a very cheap FR4 substrate with a dimension of 20x22 mm2. Also, the stair-step segments and a pentangular stub in the slot antenna provide improving the impedance bandwidth. The stair-step segments are used to tuning at a lower frequency, and a pentangular stub provides to tuning the higher frequency. The proposed antenna can operate the frequency range between 3.1 GHz to 14 GHz. The radiation pattern is bidirectional throughout the operating frequency range, while the average antenna gain is about 3.5 dBi.

This paper presents the procedures involved in the design and analysis of a microstrip broadband microwave amplifier. For system design, simulation, optimization and analysis, a Computer Aided Design (CAD) tool know as Agilent Advanced Design System (ADS) was employed. The amplifier device- FLC317MG-4 FET, was tested for stability, and was observed to be unconditionally stable between 2 to 6 GHz frequency band. Two possible ideal matching circuits were investigated to identify the best matching circuit with the maximum transducer power gain. It was observed that the quarter-wave transformer with parallel open circuit stub, gave a high gain at a wider range of frequency (larger bandwidth/ broadband), than the other matching circuit. Hence, it was employed for the broadband amplifier design using microstrips, and achieved a maximum flat gain of about 9.8 dB to 10.118 dB, at a bandwidth of 3.5 to 4.5 GHz.

This paper presents a patch antenna designed for Ultra High Frequency (UHF) Radio Frequency IDentification (RFID) reader achieving polarization and frequency agility by employing a reconfigurable feeding network inspired by stub theory. The switchable polarization improves the polarization efficiency in comparison with standard circular polarized antennas, while the frequency reconfigurability allows to use the same design to cover the European and US frequency bands. As further optimization, the patch antenna, has reduced size, for improving system integration. The combination of antenna and reconfigurable feeding network has been tested through simulations, showing a good matching over the two RFID frequency bands, while switching among four linear polarizations. The simulated results have shown a good polarization purity, however, the total efficiency is limited by the switching elements. Nevertheless, being a compact and low-cost solution, the proposed frequency and polarization reconfigurable feeding network is a good alternative to standard circular polarized designs.

The ever-growing expectation for high data rates has led to the introduction of multiple-input multiple-output (MIMO) technologies to wireless connectivity. Such a system requires an MIMO antenna with high isolation. At the same time, the MIMO dimension should not be compromised for achieving high isolation. Thus, isolation techniques that do not allow an increase in dimension need to be fostered for MIMO antenna design. In this paper, a novel low-profile, miniaturized MIMO antenna with high isolation was developed considering a split ring resonator (SRR)-based bandstop filter as a decoupling network. The bandstop filter was designed with a unit cell split ring resonator structure and was deployed between two closely spaced monopole MIMO antenna elements to obtain isolation as high as 39.25 dB at 2.61 GHz. Two open-circuit stub lines were attached with the MIMO feeding network to achieve good impedance matching at resonance frequency. The proposed antenna exhibited a peak gain of 3.8 dBi and radiation efficiency of 84%. It had a low envelop correlation coefficient (ECC &lt, 0.12), high diversity gain (DG &gt, 9.95 dB), low mean effective gain ratio (MEG 1/MEG 2 &lt, 0.05 dB), and low channel capacity loss (CCL &lt, 0.042 bits/s/Hz) at resonance frequency. The overall antenna dimension was restricted to 44&nbsp, mm&nbsp, ×22&nbsp, (0.38&nbsp, λ0×0.19&nbsp, λ0) for its easy integration in compact wireless devices.

International audience; In this paper, three state-of-the-art parallel-fed continuous transverse stub (CTS) arrays are presented. They operate at various frequency bands ranging from 20 GHz up to 86 GHz. The multiple capabilities of this architecture, such as side-lobe level reduction, active beam switching, and wideband operation with an ultra-low-profile, are here reviewed. Moreover, the suitability of the antenna concept for multiple fabrication technologies is demonstrated. The performance and key design solutions of three prototypes manufactured using milling techniques, low-temperature co-fired ceramic and printed circuit board technology are showcased. © 2021 IEICE.

A novel quad-band microstrip bandpass filter (BPF) using stepped impedance resonators (SIR), stub loaded resonator(SLR) and defect ground structure(DGS), which can be utilized in Fourth Generation Mobile Telephone Mobile Communication Standard(LTE-TDD), Direct To Home(DTH), 5-th Generation(5G) and Digital Microwave Relay Communication. The BPF was modeled and simulated by using the Ansys HFSS software. And the fabricated filter has the minimum insertion losses of 0.67 dB, 1.5 dB, 0.3 dB and 2.1 dB and the return losses 19.5 dB, 11.8 dB, 20.8 dB and 14.8 dB. By tuning the parameter of DGS, a multi-band filter can be easily optimized. This study provides a simple and effective method to design a quad-band filter with low insertion loss and compact size.

A novel approach to filter design including proof of concept is demonstrated through the first-time vertical integration of Chebyshev lowpass- and bandpass-filters in low temperature cofired ceramic (LTCC) multilayered substrates. Integration is achieved by replacing planar stub elements by resonant vertical interconnect accesses (vias) which serve the functional purpose of a vertical transmission line and therefor add another full degree of freedom in circuit design. The filters shown are comprised of two lowpass filters of 3rd- and 5th-order, and one bandpass filter of 5th-order. The general description of the design is given together with full filter specifications. Full-wave simulations based on the finite element method (FEM) and measurement results are compared to each other and are in excellent agreement.

This paper presents a new miniaturized planar Vivaldi antenna (PVA) design. The proposed antenna structure consists of an aperture tapered profile and cavity stub fed with a simple 50 Ω strip line feeding network. The designed PVA offers versatile advantages, including the miniaturized size and simple design, and exhibited an outstanding performance compared to the latest reported literature. The antenna occupies a minimal space with an electrical size of 0.92λ0 × 0.64λ0 × 0.03λ0. The antenna achieves an excellent relative impedance bandwidth 117.25% at 10 dB return loss, peak realized gain of 10.9 dBi, and an excellent radiation efficiency of 95% at the specific resonances. The antenna’s optimal features, that is, broadband, high gain, and radiation efficiency, are achieved with efficient grooves based approach. Besides, the proposed antenna results are also analyzed in the time domain, which shows the excellent group delay performance