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With the increasing demand for compact, lightweight, cost‐effective, and high‐performance radiofrequency (RF) devices, the development of low‐profile antennas becomes crucial. This article presents a study of a novel carbon–cellulose‐based paste intended for screen printing RF devices. The investigation specifically explores the application of high‐reactivity carbon mixture (HRCM) particles as conductive fillers. The results demonstrate that optimal electrical conductivity values and discrete electromagnetic dipole performances can be achieved at lower concentrations of solid conductive material compared to conventional pastes, for similar applications. This offers benefits in terms of total cost, material consumption, and environmental impact. The paste formulation showcases a complex non‐Newtonian behavior, where yielding flow and thixotropicity are found to be independent and dependent on preshear conditions, respectively. This behavior can be attributed to the network orientation and rearrangement of filler structures within the paste system, which in turn are responsible for filler pattern uniformity and overall printing quality. Compared to traditional conductive materials, HRCM pastes are proven to be a viable alternative for RF devices fabrication, including printed Wi‐Fi antennas. [ABSTRACT FROM AUTHOR]

This paper presents the design, analysis, and testing of a four states pattern reconfigurable monopole antenna intended for WLAN applications. The proposed planar monopole has two parallel parasitic elements, which are connected to the ground plane by two PIN diodes. By switching the diodes between the "ON" and "OFF" states, the function of each parasitic element can be changed from a reflector into a director. Consequently, the radiation pattern of the monopole can be reconfigured, and the direction of the main beam can be easily changed. The four states of the reconfigurable antenna can also be changed at the design stage by choosing a proper distance between the monopole and the adjacent parasitic element. The operation of the antenna is analysed, then simulated using the CST software to prove the feasibility of the proposed idea. Experimental testing of the fabricated prototype showed good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

One of the most common failures or breakdowns that can occur in high-voltage (HV) equipment is due to partial discharges (PDs). This occurs as a result of inadequate insulation, aging, harsh environmental effects, or manufacturing flaws. PD detection and recognition methods have gained growing attention and have seen great progress in the past decades. Radiometric methods are one of the most investigated detection approaches due to their immunity to electromagnetic interference (EMI) and their capabilities to detect and locate PD activities in different applications such as transformers, cables, etc. Several review articles have been published to classify and categorize these works. Nonetheless, some concepts are missing, and some improvement techniques, such as PD detection at high-frequency (HF) and very high-frequency (VHF), have been overlooked. We present in this paper an exhaustive review study of state-of-the-art PD detection based on radiometric methods at different usable radiofrequency bands (i.e., HF, VHF, and UHF). Accordingly, we propose a new generic categorization approach based on the detected electromagnetic wave component (magnetic or electric fields) and pick-up location, either from free space or ground cable. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes the formulation of a sinusoidal basis function with a novel segmented edge condition to model the impulsive behavior of the surface electric current density at the edges of rectangular microstrip scatterers. In comparison to traditional basis functions, the one considered in this approach demands using very few modes to expand the induced current. The effectiveness of the proposed formulation is validated using the commercial electromagnetic simulator Ansys Designer. Good agreement between the results obtained with the proposed formulation and with the commercial software has been obtained.

The expansion of the leading-edge communications has revealed reasonable and less cumbersome antennas that meet the needs of new technologies called printed antennas. This work represents the design and the realization of a dipole antenna stamped in "I" Topology that can transmit at a frequency of 3 GHz and fulfils a set of characteristics according to the required specifications. The antenna is designed and made using FR-4 substrate with a dielectric constant of 4.4 and a thickness of 1.6 millimeter (mm). The antenna design consists of two strands separated with distance s= 1 mm and interconnected with each other by a coaxial line that feeds the antenna with an impedance of 50 O. The antenna contains also a ground plan of the same size of the substrate and a compact size of 25 mm × 20 mm. This paper describes the steps to design and realize the antenna. It shows both simulation and experimental result where the simulation results show that the developed antenna meets the required specifications. Indeed, the printed dipole antenna gives an adaptation of -31 dB for a transmission frequency of 3 GHz with a bandwidth of 1 GHz. The experimental measurements are close to the requirement regarding resonance and adaptation (2.84 GHz, -25 dB). The proposed antenna has a simple design, lightweight, low manufacturing cost and very compact size. This makes it preferable for wireless phones applications. [ABSTRACT FROM AUTHOR]

A 3D-printed phased array consisting of four H-Sectorial horn antennas of 200 g weight with an ultra-wideband rectangular-waveguide-to-microstrip-line transition operating over the whole LMDS and K bands (24.25–29.5 GHz) is presented. The transition is based on exciting three overlapped transversal patches that radiate into the waveguide. The transition provides very low insertion losses, ranging from 0.30 dB to 0.67 dB over the whole band of operation (23.5–30.4 GHz). The measured fractional bandwidth of the phased array including the transition was 20.8% (24.75–30.3 GHz). The antenna was measured for six different scanning angles corresponding to six different progressive phases α , ranging from 0° to 140° at the central frequency band of operation of 26.5 GHz. The maximum gain was found in the broadside direction α = 0°, with 15.2 dB and efficiency η = 78.5%, while the minimum was found for α = 140°, with 13.7 dB and η = 91.2%. [ABSTRACT FROM AUTHOR]

With the rapid changes in wireless communication systems, indoor wireless communication (IWC) technology has undergone tremendous development. Antennas are crucial components of IWC systems that transmit and receive signals within indoor environments. Thus, the development of indoor technology is highly dependent on the development of indoor antennas. However, indoor environments with limited space require the fewest indoor antenna units and the smallest indoor antenna sizes possible. Hence, indoor antennas with compact size and broad applications have become widely preferred. In an IWC system, circularly polarised (CP) antennas are generally important, especially in dense indoor environments, because compared with linearly polarised (LP) antennas, CP antennas reduce polarisation mismatch and multipath losses. This paper combs through the existing studies related to three-dimensional (3D) geometry (nonplanar) or waveguide indoor antennas and the two common approaches to two-dimensional (2D) geometry (planar) indoor antennas, namely, broadband CP printed monopole antennas (BCPPMAs) and broadband CP printed slot antennas (BCPPSAs). The advantages, disadvantages and limitations of previous works are highlighted as well. These research works are summarised, compared and analysed to understand the recent specifications of BCPPMAs and BCPPSAs to generate the most appropriate design structure suitable for current IWC systems. [ABSTRACT FROM AUTHOR]

The design and analysis of a planar ultra-wideband elliptical slotted patch antenna for application in breast microwave radar system is presented in this paper. It is modelled in front of a breast phantom of cylindrical shape. No matching liquid is used in this model. A novel partial ground plane with protrusions on two sides is used for achieving good matching without any coupling medium. For effective signal penetration, a low frequency band of operation is selected. The antenna has a wide impedance bandwidth operating from around 1.8 GHz to 6.9 GHz or higher. A parametric study is conducted to understand the effects of important parameters on the antenna performance and to develop some design guidelines. The fabricated prototype was tested in the presence of a breast phantom. The transmission response of the antenna was also measured, which shows reduced transmission loss compared to a previous study since the antenna is in the air. The measured results are in good agreement with simulated data. This antenna can be used in a microwave imaging system for radar based breast cancer detection, where wide impedance bandwidth is required.

A new approximation for the Green’s function of a grounded anisotropic dielectric slab is proposed to obtain closed-form analytical expressions for the maximum radiated power of a short printed dipole on an anisotropic substrate. The corresponding surface wave (SW) power can also be accurately estimated as a root of a cubic polynomial, which makes it possible to compute radiation efficiency due to SW loss analytically. [ABSTRACT FROM AUTHOR]

This paper proposes the formulation of a sinusoidal basis function with a novel segmented edge condition to model the impulsive behavior of the surface electric current density at the edges of rectangular microstrip scatterers. In comparison to traditional basis functions, the one considered in this approach demands using very few modes to expand the induced current. The effectiveness of the proposed formulation is validated using the commercial electromagnetic simulator Ansys Designer. Good agreement between the results obtained with the proposed formulation and with the commercial software has been obtained. [ABSTRACT FROM AUTHOR]

Additive manufacturing using direct-write or screen printing represent low-waste methods for fabricating antennas on low-cost flexible substrates. To realize rectennas using low-resolution printing methods, high-impedance antennas with simple printable geometries are required. This article proposes an electrically-small (0.212 × 0.212λ2) folded dipole antenna design with a scalable impedance for directly matching energy harvesting rectifiers. The antenna is demonstrated in a high-efficiency sub-1 GHz rectenna, with varying mesh fill-factors for optical transparency. The proposed solid (non-transparent) and meshed (70%-transparent) rectennas achieve a Power Conversion Efficiency (PCE) of over 70% and 60% from sub-1μW/cm2 power densities, at 940 and 920 MHz, respectively. This represents a 37% improvement in the PCE over state-of-the-art flexible rectennas while maintaining the smallest electrical size and simplest design by not requiring a matching network. The 70%-transparent rectenna's performance is investigated in real-life use-cases showing its suitability for ambient RF energy harvesting with over 500 mV DC output from a phone-call.

As the usage of wireless technology grows, there are evermore demands on the antennas that support these platforms. This need has led to the design of unique antennas with improved bandwidth, agile frequency capabilities, compact size and greater efficiencies. In part though, the trade-off for such capabilities is antenna complexity. This paper presents a new technique for simplifying the method of changing the operation of a printed antenna using micron-sized silver coated particles that respond to magneto-static fields. More specifically, a structure consisting of a low-loss dielectric material with a cylindrical cavity containing micro-sized particles is developed. The overall size of the dielectric material is 1.5 mm × 1.5 mm × 0.5 mm and the cavity has a diameter of 0.9 mm. Furthermore, the top and bottom of the cavity with the micron-sized particles is capped with copper foil. Then, to manipulate the enclosed particles, a static magnet is placed near the structure. The enclosed particles columnize and orientate in the direction of the field-lines, connecting the top and bottom copper foil plates. To disconnect the plates then, the field is simply removed and the columns collapse. Macroscopically, the structure has the behavior of a switch. The structures presented in this work are denoted as Magneto-static Field Responsive Structures (MRSs). The MRSs have an additional benefit of not requiring a direct connection to a biasing circuit. This is very useful because there are many antenna designs that make it difficult to embed biasing circuitry to reconfigure printed antennas using MEMS and PIN diodes, for example. Finally, a new frequency reconfigurable Electromagnetic Band Gap (EBG) antenna is presented. This design is unique because the complex layout does not allow for traditional biasing circuitry and the operation is changed using the new MRSs presented in this paper.

With the rapid changes in wireless communication systems, indoor wireless communication (IWC) technology has undergone tremendous development. Antennas are crucial components of IWC systems that transmit and receive signals within indoor environments. Thus, the development of indoor technology is highly dependent on the development of indoor antennas. However, indoor environments with limited space require the fewest indoor antenna units and the smallest indoor antenna sizes possible. Hence, indoor antennas with compact size and broad applications have become widely preferred. In an IWC system, circularly polarised (CP) antennas are generally important, especially in dense indoor environments, because compared with linearly polarised (LP) antennas, CP antennas reduce polarisation mismatch and multipath losses. This paper combs through the existing studies related to three-dimensional (3D) geometry (nonplanar) or waveguide indoor antennas and the two common approaches to two-dimensional (2D) geometry (planar) indoor antennas, namely, broadband CP printed monopole antennas (BCPPMAs) and broadband CP printed slot antennas (BCPPSAs). The advantages, disadvantages and limitations of previous works are highlighted as well. These research works are summarised, compared and analysed to understand the recent specifications of BCPPMAs and BCPPSAs to generate the most appropriate design structure suitable for current IWC systems.

The design, simulations, and optimized results for a novel low specific absorption rate (SAR) monopole antenna on a single artificial magnetic conductor (AMC) cell are described in this paper. Simulated results show a reduction close to 70% in the 1 g ps SAR for the developed monopole antenna with the AMC in comparison to the monopole antenna without AMC. This allows higher radiation efficiency, battery drain reduction as well as mobile terminal user health risks reduction. [ABSTRACT FROM AUTHOR]

The main objective of our work is to design simple, low-profile and relatively high gain antenna topologies with ultra-wide Band operation. For this reason, we went to use the printed resonator antennas. They have been the subject of several researches and have acquired a great interest of the academic and industrial world. The printed antennas, by their simple and various geometries, can be fed by various usual techniques. In addition, their sizes may be smaller than their counter parts conventional antennas. The proposed antenna is designed to cover the Federal Communication Commission (FCC) bandwidth for UWB applications (3.1-15.5 GHz). Several results of the simulations of the antennas on commercial softwareHFSS, very used to the field of electromagnetism, this software is based on the method of the fine elements, and it to offer high precise calculations. Finally, all the simulation and results of VSWR are found in good agreement. [ABSTRACT FROM AUTHOR]

The design and analysis of a planar ultra-wideband elliptical slotted patch antenna for application in breast microwave radar system is presented in this paper. It is modelled in front of a breast phantom of cylindrical shape. No matching liquid is used in this model. A novel partial ground plane with protrusions on two sides is used for achieving good matching without any coupling medium. For effective signal penetration, a low frequency band of operation is selected. The antenna has a wide impedance bandwidth operating from around 1.8 GHz to 6.9 GHz or higher. A parametric study is conducted to understand the effects of important parameters on the antenna performance and to develop some design guidelines. The fabricated prototype was tested in the presence of a breast phantom. The transmission response of the antenna was also measured, which shows reduced transmission loss compared to a previous study since the antenna is in the air. The measured results are in good agreement with simulated data. This antenna can be used in a microwave imaging system for radar based breast cancer detection, where wide impedance bandwidth is required. [ABSTRACT FROM AUTHOR]

A novel coplanar waveguide-fed rectenna with high efficiency is proposed and implemented in this paper for 2.45-GHz Bluetooth/ wireless local area network applications. The antenna has compact dimensions of 18 mm × 30 mm, which is simulated and manufactured using a low-cost FR4 substrate with a thickness of 1.6 mm. A tuning stub technique with rectangular slots is used for better impedance matching and enhancing the impedance bandwidth of the antenna with a peak gain of 5.6 dB. The proposed novel antenna for RF energy harvesting applications exhibits dipolelike radiation pattern in H-plane and omnidirectional pattern in E-plane with improved radiation efficiency. Single-stage Cockcroft-Walton rectifier with L-shaped impedance-matching network is designed in advance design system and fabricated on FR4 substrate. The dc output of the rectenna is measured as 3.24 V with a load resistance of 5 kΩ. A simulated peak conversion efficiency of 75.5% is attained, whereas the measured one is observed to be 68% with an input signal power of 5 dBm at 2.45 GHz.

This paper investigates the potential of using spray coating as a methodology for flexible antenna fabrication. The methodology has advantages compared with other antenna-printing techniques, such as screen-printing and gravure printing (more flexibility in design), or inkjet printing (faster production). The methodology is demonstrated using two different types of folded dipole antennas that are designed to operate in the ultra-high frequency radio-frequency identification (UHF RFID) band. Both antennas show good agreement between simulation and measurement of the spray-coated samples in terms of power reflection coefficient and gain. The two folded dipoles, with and without ground plane, show comparable performance in terms of gain, as similar antennas found in literature. The folded dipole on a ground plane is more stable near conductive surfaces and on the human body. Given these results, we conclude that spray coating is a good technique for printing small to medium sized batches of antennas.

Design process and respective results for the synthesis of specific Radiofrequency Identification(RFID) tag antennas, suitable for dielectric and metallic objects, are presented. The antennas were designed for the UHF(865MHz-869MHz) band and their basic configuration is that of the printed spiral type. Six modification steps to the classical spiral layout are proposed and it was proved that they can lead to tags with high readability and reading distances up to 10m when designed for dielectric object and up to 7m in the case of metallic objects. The results of the measurements of the fabricated tags are explained via theoretical evaluations which take into account reflection phenomena, that are present in a real environment at which the tags are used.

In this paper the design of printed log-periodic antennas is presented. Focus is on the design of an antenna for long range communication within a wireless sensor network system for sea water quality monitoring, but the contents of the paper can also be useful at other frequencies and other applications. The difficulties in using the design procedure for log-periodic dipole antennas proposed by Carrel are discussed and some limitations are pointed out. New design hints are given, and preliminary examples of printed antennas are presented. Simulations are carried out not only for free-space but also in presence of sea and wave motion. Results show that printed log-periodic antennas can be good candidates for the intended application. [ABSTRACT FROM AUTHOR]

The compact antipodal Vivaldi antenna (AVA) with regular rectangular slots in the taper region is presented in this paper intended for electronic warfare applications. The antenna has a simple configuration with compact size. Micro strip line feeding is employed. The rectangular slots at regular intervals and terminal elliptical shaping of taper on top and bottom layers of antenna substrate enhance impedance bandwidth. The slot loading in the taper portion also enhances the gain. The novel feature of this antenna is its small aperture size which is 25 mm. Small aperture size is required for array applications to avoid grating lobes and element pattern nulls. A return loss of less than −10 dB (VSWR <2.0) is obtained over 6 to 18 GHz. The antenna is designed using Ansoft HFSS software and the same is implemented in hardware. Return loss, radiation patterns, and gain have been measured and results reported. [ABSTRACT FROM AUTHOR]

A F-shapedprinted dipole antenna, designed to operate simultaneously at 1.8 GHz, 2.45 GHz and 5.8 GHz is proposed in this work. The main challenge of the project is to find the antenna optimal geometry so that its gain has a higher value in the three operating frequencies in order to be efficiently applied it in the energy harvesting and wireless communication systems. To achieve the proposed operating condition, reduce the antenna return loss and enhance its bandwidth and gain a metamaterial surface was incorporated into its structure. All simulations and optimizations were performed using the Computer Simulation Technology software by employing the Finite Difference Time Domain technique for the electromagnetic equations evaluation. The antenna and metamaterial geometrical dimensions were optimized by using the Genetic Algorithm technique. Numerical and experimental evaluations were performed for the antenna with and without the metamaterial structure incorporated. The results obtained demonstrate the appropriately designed metamaterial ability to improve the antennas performance, increasing their bandwidth and gain and decreasing the return loss value. [ABSTRACT FROM AUTHOR]

Abstract: A quad‐band dual‐polarized monopole with asymmetrical microstrip feed line is proposed in this article. The proposed antenna exhibits a linearly polarized behavior in three operating bands for UMTS, WLAN 2.4 GHz, and WiMAX 3.5 GHz applications while a circularly polarized nature in the lowermost band for the GPS/GLONASS. The multiband operation is achieved because of λ/4 mode of resonances of three different monopole lengths and 3λ/4 mode of longer monopole. The 3λ/4 mode of larger monopole is controlled by using an L‐Shaped stub to make it useful for WiMAX application (3.5 GHz). The circular polarization for GPS (band‐L1, 1575 MHz) is achieved by using an L‐shaped slit with the ground plane which leads to generation of magnetic current orthogonal to the longest monopole current corresponding to the lowermost resonance frequency. The proposed antenna exhibits impedance bandwidths of 11.22%, 7.9%, 6.84%, and 4.26% at the resonant frequencies of 1.5, 2.02, 2.46, and 3.51 GHz, respectively. The axial ratio bandwidth corresponding to the GPS band is 2.5%. The proposed antenna has dual sense circular polarization (LHCP in θ = 0° and RHCP in θ = 180°) and bi‐directional radiation patterns at GPS/GLONASS band along with stable gain and good efficiency in all the operating bands. [ABSTRACT FROM AUTHOR]

This article describes the design of a dual-wideband annular slot antenna. The proposed structure has been optimized to operate in the typical bands of mobile communication systems (0.824-0.960 GHz and 1.710-2.165 GHz). The antenna is designed considering two independent ports with high isolation, one for each operation band, yielding an antenna that exhibits diplexing feature. The final measured results show that the designed antenna exhibits stable radiation pattern over the frequency in both desired bands. The designed antenna has been used to compose a dual-band linear array. Simulation results indicate good performance in both bands for mobile communication systems. [ABSTRACT FROM AUTHOR]

The correlation coefficient (ρ) is an important metric for the evaluation of multiple-input-multiple-output (MIMO) antenna systems because it describes the relationship between the channels in a particular propagation environment. Highly correlated channels will degrade the MIMO system performance. Various methods to calculateρare analyzed in this work using three different types of antennas with different efficiencies and radiating properties. While the field-based method for findingρgives the most accurate results and should be used all the time. It is independent of antenna efficiency. The the S-parameter-based method might give reasonable results only when the antenna efficiency is very high and the patterns are separated in space, but in most cases, it underestimatesρvalues and thus is not a reliable method and should be avoided. Incorporating the antenna efficiency can improve theρestimates using the S-parameters method under some specific conditions. The equivalent circuit method provides reasonable results for symmetric antenna structures only, and is the most complex in formulation. As part of the evaluation, two existing methods incorporating the radiation efficiency of the antennas are generalized to N-ports for the first time. Although less accurate than the field-based method, these extensions allow the evaluation ofρfor N-port antennas using only the radiation efficiency and the S-parameters of the antenna. The effect of the beam tilts onρestimation is investigated for the first time. [ABSTRACT FROM AUTHOR]

A novel design of a printed bowtie antenna without a ground plane and with size below a quarter wavelength for RFID readers is presented. Due to the lack of a ground plane, the designed antenna has omnidirectional characteristics and is insensitive to small permittivity deviations. For matching purposes without introducing gain distortion, a shorting strip connecting the radiating arms and four triangular shaped extensions of the radiating arms are added to the antenna design. Measurements show that operation in the 915 MHz band is met with a bandwidth of 13% (S11 < -10 dB) and gain around 2 dBi, while presenting an omnidirectional radiation pattern. Also, the proposed antenna design can be easily modified to operate at neighboring frequency bands. [ABSTRACT FROM AUTHOR]

Wireless communication systems are playing an important role in different sectors of human society. Printed antennas are considered as the critical enabling technologies for these systems. The technology related to the design and development of printed antennas have been continuously improved from the structural view of configuration to antenna features improvement. Electromagnetic bandgap (EBG) structures have played a significant role in improving the features of printed antennas. In this paper, authors have restricted a feature-oriented comprehensive survey on EBG-structured printed antennas. This type of survey is primarily required for the beginner working on EBG structures/EBG-structured printed antennas. Such a survey process is rarely carried out in the open literature to the best of authors' knowledge. The proposed survey process is confined only to five different feature classifications; bandwidth improvement, gain improvement, dual-band/multi-band characteristics, band-notch characteristics, and compact and low profile, respectively. [ABSTRACT FROM AUTHOR]

Design process and respective results for the synthesis of specific Radiofrequency Identification (RFID) tag antennas, suitable for dielectric and metallic objects, are presented. The antennas were designed for the UHF (865 MHz-869 MHz) band and their basic configuration is that of the printed spiral type. Six modification steps to the classical spiral layout are proposed and it was proved that they can lead to tags with high readability and reading distances up to 10 m when designed for dielectric object and up to 7 m in the case of metallic objects. The results of the measurements of the fabricated tags are explained via theoretical evaluations which take into account reflection phenomena, which are present in a real environment at which the tags are used. [ABSTRACT FROM AUTHOR]

This paper provides a review of printed antennas loaded with metamaterial particles. This novel technique allows developing printed antennas with interesting features such as multifrequency (simultaneous operation over two or more frequency bands) and multifunctionality (e. g. radiation pattern diversity). Moreover, compactness is also achieved and the main advantages of conventional printed antennas (light weight, low profile, low cost ...) are maintained. Different types of metamaterial-loaded printed antennas are reviewed: printed dipoles and patch antennas. Several prototypes are designed, manufactured and measured showing good results. Furthermore, simple but accurate equivalent models are proposed. These models allow an easy and quick design of metamaterial-loaded printed antennas. Finally, two interesting applications based on the proposed antennas are reviewed: the patch antennas are used as radiating elements of emerging active RFID systems in the microwave band and the metamaterial-loaded printed dipoles are employed to increase the performance of log-periodic arrays.

ABSTRACT A circularly polarized Y-shaped monopole antenna with L-shaped slot loaded ground-plane is proposed in this letter. The multi-band operation is achieved due to the resonances of asymmetrical monopole arms as well as the slot in the ground plane. The circular polarization for LTE (band-7, 2600 MHz) is achieved by using orthogonal and out of phase currents on surface of Y shaped monopole, whereas circular polarization for GNSS and UMTS-2100 bands is the result of interaction of currents on longer arm of Y shaped monopole and loop currents on ground, which acts as a magnetic monopole. The antenna has been designed and optimised on a low cost FR-4 epoxy substrate. The proposed antenna exhibits impedance bandwidths of 13.1, 9.7, and 7.4% at the resonant frequencies of 1.57, 2.02, and 2.55 GHz, respectively. At these three resonances, 3 dB axial ratio bandwidths of 3.7, 4.9, and 5.06% are achieved. The antenna has dual sense circular polarization, bidirectional radiation patterns, stable gain and good efficiency in the operating bands. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:298-304, 2017 [ABSTRACT FROM AUTHOR]

This work reports the development of a simple, low-profile and ultra-wideband printed antenna. The proposed antenna is based on a truncated ground plane and an impedance matching structure formed by a round junction and two chamfers; these modifications significantly increase the antenna frequency bandwidth compared to conventional microstrip antennas and ultra-wideband printed monopoles published in literature. An antenna prototype was fabricated using an Arlon DiClad 880 substrate with an electrical permittivity of 2.2. A bandwidth of 176% was attained at a central frequency of 14.9 GHz (ranging from 1.79 to 28.02 GHz). Numerical simulations and experimental results of the antenna’s radiation pattern are also reported and exhibit good agreement. To the best of our knowledge, this is the widest bandwidth from a printed antenna that has been published in the literature. [ABSTRACT FROM AUTHOR]

The paper proposes printed circularly polarized antenna with polarization reconfigurability i.e. the possibility of switching the sense of circular polarization. The antenna consists of a pair of crossed dipoles above the reflector plate - capacitive and inductive, fed by a symmetrical microstrip line, and an identical additional inductive dipole. Inductive dipoles are alternately connected to the capacitive dipole by use of PIN diodes thus changing the physical structure of the antenna which results in switching the polarization sense between LHCP and RHCP. Biasing state of diodes is externally controlled by switching board located under the reflector plate. Simulated gain in both polarization states is around 7 dBi; axial ratio (AR) is less than 3 dB in the operational range of 7% around the central frequency; reflection coefficient S11 is less than −10 dB in 10% of the bandwidth. Antenna is designed for the frequency range around 6 GHz. All simulations and optimizations have been carried out using WIPL-D program package. Analysis of obtained results proves the validity of the proposed concept. [ABSTRACT FROM AUTHOR]

Radio Frequency Identification (RFID) is a technology that allows the exchange of data through the transferring of radio frequency signals. Known also as the contactless identification, RFID system is characterized by a reader that seeks to identify objects and by a tag that is inserted into these objects. Our work focuses on the RFID tags which contain an antenna that ensures the communication with the Reader or RFID base station, and an electronic chip in which data are stored. Our paper specifically studies and analyses printed antennas and patch that are integrated into passive RFID tags. These antennas operate in the UHF (Ultra High Frequency) band and are simulated with the well-known software like IE3D (Integral Equation three-dimensional) and CST (Computer Simulation Technology). This paper explains the importance of adapting/matching between the tag's antenna and the electronic chip to improve the efficiency of the connection. [ABSTRACT FROM AUTHOR]

A modified bow-tie antenna, which finds potential use in Radio Frequency Identification (RFID) / Industrial, Scientific and Medical (ISM) applications, is proposed. Triple band operation is facilitated by applying trapezoidal truncations on both arms of the bow-tie antenna. The major attractive feature of the proposed antenna is its improved bandwidth for triple band operation particularly in different RFID bands. A considerable size reduction of the patch area is also achieved for the proposed structure. The simulated results for the return loss characteristics are in good agreement with the measured results. [ABSTRACT FROM AUTHOR]

A novel J shaped slot antenna for ultra-wide band (UWB) WiMedia is presented. The proposed antenna is designed using a microstrip to slot line cross transition on FR4 substrate with permittivity 4.4. Return loss of the antenna is from 2.8- 13GHz and occupies just 28x10 mm 2 on the PCB. Radiation patterns are stable and omni-directional. Antenna transfer function and impulse response are analyzed to study the pulse handling capability of the antenna. [ABSTRACT FROM AUTHOR]

This paper presents a small printed tri-band antenna with a reduced ground-plane effect for WLAN/M-WIMAX applications. The radiator and ground plane of the antenna are etched on a printed circuit board with an overall size of 25×24.5×0.762 mm3. A rectangular notch and a circular slot are cut from the radiator while an asymmetrical strip is attached to the radiator. The simulation and measurement suggest that the printed antenna achieves three operating bandwidths of 2.4-2.484 GHz and 5.15-5.35 GHz for WLAN, 3.3-3.69 GHz for M-WIMAX for a 10-dB return loss, and high gains on Y-Z plane of 2.1, 3.3 and 4.8 dB at 2.4, 3.5 and 5.2 GHz, respectively. In particular, the ground-plane effect on impedance performance is significantly reduced by minimising the size of the ground plane and then by cutting a notch and a circular slot from the radiator because the electric currents on the ground plane are significantly suppressed at all the operating bandwidths. In addition, a study on the geometrical and electrical parameters of the proposed antenna may be a useful reference for antenna engineers. [ABSTRACT FROM AUTHOR]

Communication industry is in rapid growth in the last years. Efficient small antennas are crucial in the development of medical systems. Low efficiency is the major disadvantage of small antennas. Meta material technology is used to improve the efficiency of small antennas. Design tradeoffs, computed and measured results of wearable meta-materials antennas with high efficiency are presented in this paper. All antennas were analyzed by using 3D full-wave software, ADS. The antennas electrical parameters on the human body are presented. The gain and directivity of the patch antenna with split-ring resonators, SRR, is higher by 2.5 dB than the patch antenna without SRR. The resonant frequency of the antennas with SRR is lower by 5% to 10% than the antennas without SRR. The resonant frequency of the antenna with SRR on human body is shifted by 3%. [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a systematic methodology to aid design a low-cost patch antenna for RFID readers. The geometric antenna parameters are found using multiobjective optimization for return loss minimization and gain maximization. To assess the use of low-cost FR-4 substrate the radiation efficiency has been investigated using software simulations. A prototype antenna was built and its parameters were measured in the anechoic chamber. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:905-908, 2016 [ABSTRACT FROM AUTHOR]

A flexible printed near-field resonant parasitic (NFRP) GPS L1 antenna that is a compact, efficient, directive radiator is demonstrated. The simple uniplanar design incorporates a capacitively loaded loop (CLL) resonator, which acts as the NFRP element, and a coplanar waveguide (CPW)-fed semi-loop antenna. A set of slots is introduced into the CPW feedline ground strips. The resulting meander-line-shaped CPW ground strips act as a driven dipole element that is capacitively coupled to the NFRP element in such a manner that when they are properly tuned, nearly complete matching to the 50-Ω source is achieved with no matching circuit, and the pair acts as a two-element endfire array. Parameter studies are reported to illustrate the nuances of the design and its operating mechanisms. The experimental results are in good agreement with their simulated values. The endfire realized gain is 3.57 dBi with a 13.44-dB front-to-back-ratio (FTBR) at its resonance frequency: 1.574 GHz (GPS L1), where the electrical size ka = 0.97. The flexibility of the proposed antenna is demonstrated both numerically and experimentally by mounting it on several cylindrical structures whose curvatures vary over a large range and by confirming that there is little impact on its operational frequency, impedance matching, bandwidth, and radiation characteristics. [ABSTRACT FROM PUBLISHER]