Showing papers in "International Journal of Rf and Microwave Computer-aided Engineering in 2017"
TL;DR: In this article, a comprehensive investigation of research carried out on dielectric resonator antennas (DRAs) in the last three and half decades, in an application-oriented approach, is presented.
Abstract: This survey article outlines a comprehensive investigation of research carried out on dielectric resonator antennas (DRAs) in the last three and half decades, in an application-oriented approach. DRAs have created a remarkable position in antenna engineering for their adept characteristics like high efficiency, low loss, wide bandwidth, compact size, 3-dimensional modeling flexibility, etc. The use of DRAs for different commercial and defense applications associated with the wireless communication is highlighted in this article. To make a smooth and effective survey article, all the application-oriented DRAs available in the open literature are classified in five different categories like microwave bands, specific frequency, technology, millimeter-wave, and miscellaneous types. The ultimate aims of this review article are as follows: (i) highlights the usability of DRAs for different commercial and defense applications, (ii) helpful for the antenna industries/manufacturers to find out the best DRA for any specific application as per their requirement, and (iii) points out research gap in some application domains which will be quite helpful for future antenna researchers. In the authors' opinion, this survey may be helpful to DRA researchers as such a survey process is not available in the open literature.
52 citations
43 citations
TL;DR: The technical perspective discusses the theoretical aspects, simulation design procedures, and the measurement setup used to characterize the AMC unit cell, and various recent works of antenna design that involve the incorporation of AMC are discussed thoroughly.
Abstract: Artificial Magnetic Conductor (AMC) is a type of implemented metamaterial in several antennae and microwave design applications. By utilizing the unique characteristics of metamaterials which do not exist naturally, the performance of various microwave devices can be enhanced. This article elaborates on the technical perspective and recent works on AMC for antenna applications. The technical perspective discusses the theoretical aspects, simulation design procedures, and the measurement setup used to characterize the AMC unit cell. Subsequently, various recent works of antenna design that involve the incorporation of AMC are discussed thoroughly. Each of the recent works is highlighted with specific performance enhancements that can be achieved with the introduction of AMC. The conventionally narrow band property of AMC, which is the bandwidth at which the radiation characteristics and directivity of the antenna can be manipulated, is discussed. The property limits the applications of AMC in wideband antenna applications. One of the techniques to improve the narrow band AMC as the ground plane is discussed in detail. The employment of AMC has solved many issues whilst overcoming the typical limitations in conventional antenna designs.
38 citations
TL;DR: In this article, the authors proposed a compact (43 × 26 × 08 mm3) dual-band two-element metamaterial-inspired MIMO antenna system with high port isolation for LTE and WiMAX applications.
Abstract: This article proposes a compact (43 × 26 × 08 mm3) dual-band two-element metamaterial-inspired MIMO antenna system with high port isolation for LTE and WiMAX applications In this structure, each antenna element consists of a square–ring slot radiator encircling a complementary split ring resonator A tapered impedance transformer line feeds these radiating apertures and shows good impedance matching A 2 × 3 array of two-turn Complementary Spiral Resonator structure between the two antenna elements provides high dual-band isolation between them The fabricated prototype system shows two bands 234 – 247 GHz (suitable for LTE 2300) and 335 – 364 GHz (suitable for WiMAX) For spacing between two antennas of 10 mm only, the measured isolation between the two antenna elements in the lower band is around −32 dB while that in the upper band is nearly 18 dB The system shows a doughnut-shaped radiation patterns The peak measured antenna gains for the proposed MIMO system in the lower and higher bands are 39 and 42 dBi, respectively The MIMO system figure of merits such as the envelope correlation coefficient, total efficiency are also calculated and shown to provide good diversity performance
35 citations
TL;DR: In this article, a triple-band multistubs loaded resonator printed monopole antenna is proposed, which consists of a quarter wavelength two asymmetrical inverted inverted L-shaped stubs to excite two resonant modes for 3.5/5.5 GHz bands and one integrated horizontally T-shape stub with inverted long L -shaped stub toexcite resonant mode for 2.5GHz band.
Abstract: In the present article, a compact triple-band multistubs loaded resonator printed monopole antenna is proposed. The antenna consists of a quarter wavelength two asymmetrical inverted L-shaped stubs to excite two resonant modes for 3.5/5.5 GHz bands and one integrated horizontally T-shaped stub with inverted long L-shaped stub to excite resonant mode for 2.5 GHz band. By loading these stub resonators along y-axis with distinct gaps, the antenna resonates at three frequencies 2.57/3.52/5.51 GHz covering the desired bands while keeping compact size of 24 × 30 mm2 (0.2 λ0 × 0.25 λ0). The proposed antenna is fabricated on Rogers RT/duroid 5880 substrate with thickness 0.79 mm and its performance experimentally verified. The measured results reveal that the antenna has the impedance bandwidths of about 210 MHz (2.50-2.71 GHz), 260 MHz (3.37-3.63 GHz), and 650 MHz (5.20-5.85 GHz), for 2.5/3.5/5.5 GHz WiMAX and 5.2/5.8 GHz WLAN band systems. The antenna provides omnidirectional radiation patterns and flat antenna gains over the three operating bands. In addition, the design approach and effects of multistubs resonator lengths on the operating bands are also examined and discussed in detail.
28 citations
TL;DR: In this article, the authors presented a technique to enhance the broadside gain of a CPW fed slot antenna using a single layer metamaterial (MTM) superstrate.
Abstract: This article presents a technique to enhance the broadside gain of a CPW fed slot antenna using a single layer metamaterial (MTM) superstrate. A finite array of 3× 3 ring unit cell has been designed on both sides of a dielectric substrate to form the MTM superstrate. The gain enhancement is obtained using the zero-index property of the metamaterial. The broadside gain enhancement for the proposed antenna is 7.4 dB more in comparison to that of the reference slot antenna. The proposed MTM superstrate loaded antenna provides a minimum overall thickness in the context of using ZIM superstrate for gain enhancement of antennas reported in earlier literatures. The overall thickness of the MTM loaded antenna is 0.13λ0, where λ0 is the free-space wavelength at the resonance frequency of the antenna. Also, a high efficiency of about 93.2% is obtained in this case. The loading of the MTM superstrate produces a minimal effect on the cross polarization performance of the proposed slot antenna.
26 citations
25 citations
TL;DR: In this article, a phase correcting lens (PCL) made up of nonresonant rectangular patch unit cells (UCs) is proposed to correct the problem of the conventional Vivaldi antenna (CVA).
Abstract: Gain of the conventional Vivaldi antenna (CVA) decreases at higher frequencies. A phase correcting lens (PCL) made up of nonresonant rectangular patch unit cells (UCs) is proposed to correct this problem. The layout of the UCs is specially designed taking into account the actual phase error at antenna aperture. The detailed analysis, design and discussion for the CVA with the proposed PCL are performed. The CVA, CVA with one-layer PCL (CVA-OPCL), and three-layer PCL (CVA-TPCL) are fabricated and measured. The measured results agree well with the simulated ones. The measured results show that the proposed CVA-TPCL provides a gain variation of 5.75-14.9 dBi in the wide operating range from 3.5 to 16 GHz, which leads to 1.1-6.1 dBi gain enhancement than that of the CVA. In addition, the E-plane half power beamwidths become narrowed significantly at higher frequencies. An average improvement of 4.54 dB is achieved in terms of the front-to-back ratio. The sidelobe levels, on average, are reduced by 4.1 dB and 2.8 dB for E-plane and H-plane, respectively.
23 citations
TL;DR: In this article, a dual-band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications is designed and investigated, which operates at 3.5 and 5.25 GHz bands.
Abstract: A novel dual-band MIMO dielectric resonator antenna with high port isolation for WiMAX and WLAN applications is designed and investigated. The proposed antenna operates at 3.5 and 5.25 GHz bands. High port isolation is achieved using hybrid feeding mechanism that excites two orthogonal modes at each frequency bands. The measured impedance bandwidth of the proposed antenna covers the entire WiMAX (3.4–3.7) GHz and WLAN (5.15–5.35) GHz bands. The scalable behavior along with the frequency ratio of the antenna has also been investigated in this work. The measured isolation between antenna ports is −52 dB at the lower band and −46 dB at the upper band, respectively. Envelope correlation coefficient, diversity gain and mean effective gain have also been investigated. Moreover, measured results are in good agreement with the simulated ones.
22 citations
TL;DR: In this paper, an improved flexible approach that use bat algorithm is proposed and applied to solve the problem of antenna array failure by controlling only the amplitude excitation of array elements, which improves the quality of the solution and the speed of convergence.
Abstract: The failure of antenna array elements causes disturbance in the sidelobe power level. In this article, an improved flexible approach that use bat algorithm is proposed and applied to solve the problem of antenna array failure by controlling only the amplitude excitation of array elements. An adaptive inertia weight approach is applied to the standard bat algorithm to improve the quality of the solution and the speed of convergence. The effectiveness of the proposed improved bat algorithm (IBA) is verified on different standard test functions. Numerical examples of element failure correction are presented to show the capability of this flexible approach in antenna array failure correction.
22 citations
TL;DR: In this paper, a method for fast design optimization of broadband antennas is considered based on a feature-based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points.
Abstract: In this work, a method for fast design optimization of broadband antennas is considered. The approach is based on a feature-based optimization (FBO) concept where reflection characteristics of the structure at hand are formulated in terms of suitably defined feature points. Redefinition of the design problem allows for reducing the design optimization cost, because the dependence of feature point coordinates on antenna dimensions is less nonlinear than for the original frequency characteristics (here, S-parameters). This results in faster convergence of the optimization algorithm. The cost of the design process is further reduced using variable-fidelity electromagnetic (EM) simulation models. In case of UWB antennas, the feature points are defined, among others, as the levels of the reflection characteristic at its local in-band maxima, as well as location of the frequency point which corresponds to acceptable reflection around the lower corner frequency within the UWB band. Also, the number of characteristic points depends on antenna topology and its dimensions. Performance of FBO-based design optimization is demonstrated using two examples of planar UWB antennas. Moreover, the computational cost of the approach is compared with conventional optimization driven by a pattern search algorithm. Experimental validation of the numerical results is also provided.
TL;DR: This article aimed at developing a novel rectifying circuit to be used in harvesting applications at a frequency of 900 MHz and to enhance the output voltage of Cockcroft Walton rectifier circuit and Dickson rectifier.
Abstract: Many researchers continue to look for novel means to harvest energy and generate power using existing sources thus eradicating the need of batteries and power supplies which only add up to the cost of the system. A rectifier is the main component in energy harvesting circuits as it converts RF energy from available sources to DC power. This article aimed at developing a novel rectifying circuit to be used in harvesting applications at a frequency of 900 MHz. Besides, it is also aimed to enhance the output voltage of Cockcroft Walton rectifier circuit and Dickson rectifier. The design is built by integrating the Cockcroft Walton rectifier, arranged in series, with the Dickson rectifier, arranged in parallel. A Schottky diode HSMS 285C is selected for designing the rectifiers circuit. A simulation of the circuit was optimized utilizing ADS 2009. The rectifiers had been fabricated on an RT/Duroid 5880 (RO5880) printed circuit board (PCB) substrate with a dielectric constant and loss tangent of 2.2 and 0.0009, respectively. Simulation and experimental results show great output thresholds for the three models. The novel rectifier had the highest efficiency and output voltage.
TL;DR: In this article, the authors proposed an ultra-wideband coplanar strips (CPS) rectangular spiral antenna that is fed by a CPW and operates in the frequency band (3.5-10.6 GHz) and has miniaturized size of 50 × 40 × 0.508 mm.
Abstract: This article proposes an ultra-wideband coplanar strips (CPS) rectangular spiral antenna that is fed by coplanar waveguide (CPW). The CPS is formed by gradually reducing the width of the CPW ground planes without the need of a balun. The antenna operates in the frequency band (3.5-10.6 GHz) and has miniaturized size of 50 × 40 × 0.508 mm on a Rogers RO4003C substrate. The CPS spiral is terminated with a 100 Ω chip resistor for matching. A parametric study was performed to choose the CPS spiral dimensions. A good agreement is found between simulations and measurements in the radiation pattern and the return loss which was found to be better than 10 dB over the band. The measured peak gain ranges between 1 and 4.7 dBi.
TL;DR: In this paper, a two-layered RFID tag antenna designs exhibiting improved performance descriptors for on-body applications are presented, which operate in the microwave band (2.4-2.48 GHz) ensuring high data transmission rates ideal for realtime subject monitoring applications.
Abstract: In this article, a couple of two-layered RFID tag antenna designs exhibiting improved performance descriptors for on-body applications are presented. The antennas are designed to operate in the microwave band (2.4–2.48 GHz) ensuring high data transmission rates ideal for real-time subject monitoring applications. The radiating element of both the antennas is a slotted patch structure provisioned with a pair of T-shaped slots realized on a commercial FR4 substrate. The augmentation of a systematic sequence of narrow comb-like etchings into the design enhances the impedance bandwidth considerably. A high permittivity silicon layer embedded with the radiating patch provides resilience from the human body dielectric losses. A modified antenna design utilizing patch miniaturization technique, resulting in an overall footprint reduction by 32%, is also proposed. The designed tag antennas offer a gain of more than 1.8 dBi and an attractive read range greater than 6.8 m in the operating band.
TL;DR: In this paper, a wideband circularly polarized half-split cylindrical dielectric resonator antenna (HS-CDRA) having two layers with different permittivity in radial direction is investigated.
Abstract: In this article, a wideband circularly polarized half-split cylindrical dielectric resonator antenna (HS-CDRA) having two layers with different permittivity in radial direction is investigated. Designed antenna is excited by a new modified CPW fed which consists of signal line, helps to realization of circular polarization, half-split cylindrical dielectric resonator (HS-CDR), to confirm that circular polarization in proposed antenna. HS-CDR is made of two different materials which can supports to enhance the input impedance bandwidth and 3-dB axial ratio bandwidth. From the distributions of E-fields in HS-CDRA, it is observed that TM11δ mode has been excited. To confirmed the circular polarization in proposed antenna, E-field distribution on different phases (φ = 0o, 90o, 180o, and 270o) have been plotted. This antenna provides measured −10 dB input impedance bandwidth of 25.94% (centered on 4.70 GHz) and 3-dB axial ratio bandwidth in broadside direction of 17.34% (centered on 4.90 GHz). The average gain and radiation efficiency in working band are 1.56 dBi and 93.43% in broadside direction, respectively. CP radiation pattern shows that the proposed antenna has left hand circular polarization and this developed antenna could be useful for wireless applications like WLAN/Wi-MAX bands.
TL;DR: In this article, a dual-band frequency selective surface (FSS) is placed perpendicularly into the apertures of horn antennas for prefiltering 900 and 1800 MHz GSM signals interfering during the signal reception, with the enhanced return loss, gain and directivity at the desired frequencies.
Abstract: In this work, a dual-band frequency selective surface (FSS) is proposed to be placed perpendicularly into the apertures of horn antennas for prefiltering 900 and 1800 MHz GSM signals interfering during the signal reception, with the enhanced return loss, gain, and directivity at the desired frequencies. For this purpose, the microstrip double square loop MDSL is modified in the first stage. As for the second stage, an FSS array (2 × 2) is built up arranging the unit MDSLs in a periodic structure and finally these FSS unit arrays are fixed perpendicularly covering the aperture of a ridged horn antenna which is a part of the available radar system operating between 0.5 and 3 GHz in our laboratory, to construct an integrated module having both bandstop prefilter and horn antenna called “filtenna.” The simulated and experimental results are agreed that the proposed FSS structure attenuates GSM signals at the 900 and 1800 MHz through the high reflection and very poor transmission mechanisms meanwhile enhances return loss characteristics, radiation pattern, and gain of the horn antenna in the desired band. Thus, it can be concluded that these simple microstrip FSS structure can be effectively adapted to the horn antennas which need the GSM prefiltering.
TL;DR: A comprehensive review of the analytical and numerical methods used in modeling of electromagnetic band-gap (EBG) structures used in around last two decades can be found in this article, where the authors present an inclusive review of analytical methods as well as numerical methods in the context of modeling of EBG-structures.
Abstract: This article represents a comprehensive review of the research carried out on analytical and numerical methods modeling of electromagnetic band-gap (EBG) structures used in around last two decades. Because of the unique characteristics of the surface wave reduction as well as perfect magnetic conductor (PMC) like behavior, the EBG structures have created their separate existence in antenna engineering society. These structures are being widely used in designing of several microwave planar circuits including printed antennas, printed microwave filters, etc. The purpose of this article is to present an inclusive review of analytical methods as well as numerical methods in the context of modeling of EBG-structures. Such a review process is rarely carried out in the open literature to the best of authors' knowledge. The review exercise might be helpful to the researchers working on modeling of EBG-structures as well as of EBG-structured printed antennas, microwave planar filters, etc.
TL;DR: In this paper, a simple and single element wide slot dipole loaded shorted rectangular microstrip antenna has been proposed and investigated experimentally for broad impedance bandwidth and improved cross polarized (XP) radiation compared to maximum co-polarized (CP) gain.
Abstract: A simple and single element wide slot dipole loaded shorted rectangular microstrip antenna has been proposed and investigated experimentally for broad impedance bandwidth and improved cross polarized (XP) radiation compared to maximum co-polarized (CP) gain without changing the co-polarized (CP) radiation pattern Around 23-35 dB isolation between CP and XP radiation along with 25% impedance bandwidth is achieved with the proposed structure The measured gain of the antenna is around 62 dBi over the entire band The present antenna is very simple and easy to manufacture Unlike the other structures, the present one is free from back radiation in terms of XP fields The design of the antenna structure is theoretically justified and rigorously analyzed The present investigation provides an insightful, clear visualization-based understanding of the concurrent improvement in both the impedance bandwidth and XP performance with the present structure
TL;DR: A Compact Dual Band-Bandpass Filter (DB-BPF) with wide stopband rejection is proposed in this article, where the basic tools used in the structure are Short Circuited Stepped Impedance Resonators (SCSIR), Open Stub Resonator (OSR), and Short Circulated Stepped Impendedance Resonants (SCR) to generate transmission zero.
Abstract: A Compact Dual Band-Bandpass Filter (DB-BPF) with wide stopband rejection is proposed in this article The basic tools used in the structure are Short Circuited Stepped Impedance Resonators (SCSIR), Open Stub Resonators (OSR) First, a Single Band-Bandpass Filter (SB-BPF) is designed with wide stopband rejection, and then it is modified to DB-BPF Both the SB-BPF and DB-BPFs have similar type of construction except for an additional SCSIRs used in DB filter The structure of the filters, use the source-load coupling and OSR to generate transmission zeros, which suppresses harmonics and achieves wide stopband The use of SCSIRs make the SB and DB bandpass filters size compact to 0099λg×0094λg and 0118λg×0092λg, where λg is guided wavelength with a wide stopband upto 685f0 with 22 dB suppression for SB-BPF and 278f1/757f0 with 22 dB suppression for DB-BPF, where f0 and f1 are centre frequencies of first and second passbands respectively
TL;DR: In this article, a comparative analysis for the performance of single, 2 × 2, and 4 × 4 dielectric resonator (DR) and patch circularly polarized (CP) antenna subarrays at 30 GHz is presented.
Abstract: This article presents a comparative analysis for the performance of single, 2 × 2, and 4 × 4 dielectric resonator (DR) and patch circularly polarized (CP) antenna subarrays at 30 GHz. In order to enhance the CP bandwidth, the subarray elements are fed by two kinds of sequential feeding techniques using parallel and hybrid ring feeds. The 4 × 4 patch antenna subarrays fed by parallel and hybrid ring feeding networks are fabricated and tested. Measurements show acceptable agreement with simulation results. The experimental results show a bandwidth of 36.9% for both (−10 dB) impedance matching and (3 dB) axial ratio CP patterns for the patch subarray antenna with hybrid ring feeding. For the parallel feeding, the corresponding bandwidth is 28.81%. The proposed antennas combine desirable features such as wide impedance and AR bandwidths, low profile, and easiness of fabrication and therefore is a good candidate for millimeter wave systems around 30 GHz.
TL;DR: In this article, a frequency-reconfigurable antenna for multiband (GSM850/900/GLONASS1616/DCS1800/PCS 1900/UMTS/LTE2300/2500/WLAN) mobile handset applications is presented.
Abstract: A frequency-reconfigurable antenna is presented for multiband (GSM850/900/GLONASS1616/DCS1800/PCS 1900/UMTS/LTE2300/2500/WLAN) mobile handset applications. It mainly consists of radiating elements with two PIN diodes. By switching the ON/OFF states of the PIN diodes, the proposed structure can operate in three states: OFF–ON, ON–OFF, and ON–ON. When PIN diodes are in the OFF–ON states, the proposed antenna can cover the GSM850/900, PCS1900, and UMTS2100 bands by operating in Invented-F antenna (IFA) mode. When PIN diodes are in the ON–OFF states, the antenna can cover the LTE2300/2500 and WLAN2400 bands in monopole mode. Moreover, when PIN diodes are switched to the ON–ON states, the designed antenna works in loop mode and its resonant frequencies include the GLONASS1616, DCS1800/1900, and LTE2500 bands. With the reconfigurable technique, the proposed antenna achieves a compact size of 15 × 28.5 mm2 with high efficiency from 34% to 84.86% in the total frequency range.
TL;DR: Values of frequency bandwidth, dielectric constant of antenna's substrate, electric field, and tumor information were consisted in the dataset obtained from the Bow‐Tie Antenna and used to detect the breast cancer with one of the data mining method, which is K‐Nearest Neighbor Algorithm.
TL;DR: In this article, a new class of dual/tri-band and ultra-wideband bandpass filters using novel multi-mode resonators is proposed, which exhibit controllable resonant modes with different dimension parameters under the same configuration.
Abstract: In this article, a new class of dual-/tri-band and ultra-wideband UWB bandpass filters BPFs using novel multi-mode resonators are proposed. The classical even-/odd-mode method is applied to analyze the resonant characteristics of the proposed resonators, which exhibit controllable resonant modes with different dimension parameters under the same configuration. According to the analysis, three resonators with quad-/penta-/sext-mode resonant characteristics are obtained by choosing the specific dimension parameters. Then, the quad-mode resonator is used to design a dual-wideband BPF centred at 2.39/5.14 GHz with 3-dB fractional bandwidths FBWs of 36.9%/18.9%, and the penta-mode resonator is utilized to design an UWB BPF with 3-dB FBW of 102.2%, whereas the sext-mode resonator is applied to design a tri-band BPF with centre frequencies of 2.09/3.52/5.46 GHz and 3-dB FBWs of 11.3%/20%/12.1%. All these three filters are fabricated and measured, and the measured results are in good agreement with the simulated ones.
TL;DR: This work demonstrates a possibility of dramatic reduction of the number of training samples, which is achieved by reformulating the modeling problem in a space of appropriately defined response features, and indicates that accuracy that is sufficient for practical antenna design.
Abstract: Accurate and low-cost models of input characteristics are of primary importance from the point of view of efficient design of antenna structures. Yet, the modeling problem is difficult because reflection responses are highly nonlinear functions of frequency and change considerably when adjusting antenna dimensions. Conventional approximation-based models require massive datasets and often fail to provide required accuracy. This work demonstrates a possibility of dramatic reduction of the number of training samples, which is achieved by reformulating the modeling problem in a space of appropriately defined response features. The key factor is that dependence of feature point coordinates (both frequency and level) on antenna dimensions is less nonlinear than for the standard responses (S-parameters vs. frequency). Our methodology permits construction of reliable surrogates using much smaller datasets than those required by conventional approaches. Experimental validation indicates that our models provide accuracy that is sufficient for practical antenna design.
TL;DR: In this paper, a novel square ring printed antenna has been proposed for dual-band circular polarization (CP), which contains a square patch and a square ring structure for dualband operation.
Abstract: A novel square ring printed antenna has been suggested for dual-band circular polarization (CP). The geometry contains a square patch and a square ring structure for dual-band operation. Circular polarization is achieved using triangular cut at the boundary and right angle bend with inner perturbation. The suggested antenna is excited from the lower layer through electromagnetic (EM) coupling technique. The antenna shows good impedance bandwidths of 90 MHz (2.43-2.52 GHz) and 800 MHz (5.7-6.5 GHz, respectively. The antenna shows 3 dB axial ratio bandwidth of 20 MHz at lower band and 120 MHz at upper band with improved gain > 6 dBi. The simulated and measured results are well agreed with each other. The antenna is promising wideband operation at the upper band. This antenna was implemented on fiberglass reinforcement laminated Arlon substrate with dielectric constant (ɛr = 2.55), and the overall physical dimension of 30 × 30 × 3.048 mm3. The designed antenna can be extensibly applicable in WLAN/Wi-MAX communication. The presented antenna is designed using hyperlynx IE3D and the simulated results are presented.
TL;DR: In this article, a comprehensive analysis of the waveform-engineering based design techniques is reported, paying particular attention to the advantages and drawbacks associated with each approach, with the focus on the model-based and measurement-based approaches.
Abstract: The term waveform engineering denotes all those circuit design techniques that are based on shaping the transistor voltage and current waveforms. From a general perspective, these design techniques can be grouped in two main categories according to the adopted design tool: measurement- and model-based. In the last two decades, thanks to the proliferation of setups enabling calibrated waveform acquisition at microwave frequencies, waveform engineering has attracted continuously increasing interest in the microwave engineering community. In this article, a comprehensive analysis of the waveform-engineering based design techniques is reported, paying particular attention to the advantages and drawbacks associated to each approach.
TL;DR: In this paper, a pair of unsymmetrical dual-feed antennas with one shared radiator and two isolated ports is proposed for multiple-input-multiple-output (MIMO) systems.
Abstract: In this article, a pair of unsymmetrical dual-feed antennas with one shared radiator and two isolated ports is proposed for multiple-input-multiple-output (MIMO) systems. The proposed antenna pair achieves high isolation between the two ports by properly adjusting the distance between the two feeding ports and the position and length of shorting strips on the radiator. The antenna has simple structure and covers the 3.3-3.7 GHz band, which could meet the demand of future 5G applications. The measured results show that antenna has good impedance matching (better than 10 dB return loss) and high port isolation (better than 20 dB isolation) from 3.35 to 3.65 GHz. The total efficiencies are above 55% and the envelope correlation coefficient is <0.1, which is sufficient for MIMO applications.
TL;DR: In this article, a dual-band, dual-circularly polarized antenna is proposed and fabricated, which consists of an asymmetric U-shaped slot and an inverted L-shape slot which are designed to excite two orthogonal E vectors with equal amplitude and 90° phase difference.
Abstract: A novel dual-band, dual-circularly polarized antenna is proposed and fabricated. The proposed antenna consists of an asymmetric U-shaped slot and an inverted L-shaped slot which are designed to excite two orthogonal E vectors with equal amplitude and 90° phase difference (PD), in addition, fed by a coplanar waveguide (CPW) Furthermore, a left-hand circular polarization in the direction of z > 0 and a right-hand circular polarization instead of the opposite direction both at the lower and upper bands are exhibited by the radiations of the antenna. Good agreement is achieved between the measurement and simulation, which indicates that a 10-dB bandwidth of 38.75% from 2.56 to 3.8 GHz and 21.8% from 10.01 to 12.53 GHz, while a 3-dB axial-ratio bandwidth (ARBW) of 13.4% from 2.77 to 3.2 GHz and 9.23% from 10.25 to 11.25 GHz at two operation bands, respectively, are covered in the designed antenna. To explain the mechanism of dual-band dual-circular polarization, the analysis of magnetic fields distributions and a parametric study of the design are given. Meanwhile, compared to other recent works, a single layer structure, wider axial ratio and impedance bandwidths and a more compact size are the key features of the proposed antenna.