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A flexible printed monopole antenna integrated with artificial magnetic conductor (AMC) working at 2.45 GHz is designed and analyzed. The proposed antenna is suitable for the industrial, scientific, and medical (ISM) band, WIFI and Bluetooth applications. The artificial magnetic conductor (AMC) is used to enhance the antenna characteristics and to isolate the antenna from human body effects that produces by proximity coupling. The antenna has ultra-low profile which is about $0.028 \lambda0$. The simulated results show a good improvement in gain from 0.82 dB to 2.61 dB, efficiency from 78.56% to 88.72% and the radiation pattern change from omni-direction to uni-direction which it suitable for wearable applications.

Recent wearable health monitoring systems use multiple biosensors embedded within a wireless device. In order to reliably transmit the desired vital signs in such systems, a new set of antenna design requirements arise. In this paper, we present a flexible, ultra-low profile, and compact dual band antenna. The proposed design is suitable for wearable and flexible telemedicine systems and wireless body area networks (WBANs). The antenna is inkjet printed on a 50.8µ mP olyimide Kapton substrate and fed by a Coplanar Waveguide (CPW). The proposed design has the merits of compactness, light weight, wide bandwidth, high efficiency, and mechanical stability. The performance of the antenna is also characterized against bending and rolling effects to assess its behaviour in a realistic setup since it is expected to be rolled on curved surfaces when operated. The antenna is shown to exhibit very low susceptibility to performance degradation when tested against bending effects. Good radiation characteristics, reduced fabrication complexity, cost effectiveness, and excellent physical properties suggest that the proposed design is a feasible candidate for the targeted application.

The research reported in this paper aims at developing means of Non Destructive testing (NDT) to increase the line efficiency of pipe production in oil and natural gas pipe manufacturing plants using the Standard Allowed Minutes (SAM) method. Existing line production stations encounter difficulties in maintaining the recommended testing speed of smaller diameter pipe, due to limitations in the Visual Inspection (VI) station. We propose to implement one additional technique which will prevent the decline of line efficiency in a pipe production factory. The range of diameters identified as a problem in this research is from 254 mm to 762 mm. Microwave techniques are expected to improve the line efficiency by increasing the production of the plant. This happens as a consequence of maintaining the production rates of the identified pipe diameters, so that they equal the production output of the larger pipe diameters. We analyze the velocity traveled by the pipe through Radiographic Testing (RT) according to the VI output (production). The RT velocity is decreased for the diameters identified above, in order to maintain quality control and cover the shortcoming of the VI. The number of pipes produced is computed during shift hours of the factory and pipe lengths of the forming department are determined. We compare the output (production) of a series of NDT line stations with and without the microwave technique for the first of the three pipe cases considered in this study, classified as perfect pipe (PP), repair pipe (RP) and scrap pipe (SP). The velocity of RT stations analyzed in the paper ranges from 50 mm/s for larger diameter pipe, and decline to 16.667 mm/s for the identified diameters. The analytical calculations of line output (production) and line efficiency demonstrate the solution of this velocity problem after the microwave technique is introduced. It demonstrates that an economical and precise methodology to extend the production capability of the pipe plant has been determined.

In this paper, two vertical metallic strips printed on a dielectric substrate are utilized to enhance the isolation between two monopoles. Each monopole is fed by a coplanar waveguide. The monopoles are placed in a close proximity of 10 mm, 0.08 λ o , where λ o is the wavelength at 2.4 GHz. The two-antenna array provides a bandwidth of 90 MHz (2.39 GHz–2.48 GHz) over which S 11 and S 22 are ≤ −10 dB and S 21 ≤ −17 dB and a bandwidth of 60 MHz in which S 21 is ≤ −20 dB. The isolation in terms of S 12 has been reduced by 14 dB from −9 dB when no decoupling structure is used. The array achieves a realized gain of 1.84 dB. The design represents a good candidate for modern wireless systems utilizing MIMO techniques including Wi-Fi, 4G LTE, as well as systems utilizing ISM spectrum.

Recent years have witnessed a great deal of interes t from both scientific and academic communities in the field of flexible electronic systems. Most flexible electronic systems require the integration of flex ible antennas operating in specific frequency bands to p rovide wireless connectivity which is highly demand ed by today’s network oriented society. On the other h and, High Impedance Surfaces have become very popular in the design of contemporary antenna and micro-wave devices due to their wide range of applications derived from their unique electromagne tic properties which significantly enhance the performance of antennas and RF systems. Accordingly, the integration of HIS structures within flexible wireless systems is very beneficial in this growing field of research. In this paper, a systematic rev iew of flexible HIS structures reported in the literature is conducted, which provides the reader with a thor ough description and a complete list of state of the art designs intended for flexible wireless systems.

We present a flexible, compact antenna system intended for telemedicine applications. The design is based on an M-shaped printed monopole antenna operating in the Industrial, Scientific, and Medical (ISM) 2.45 GHz band integrated with a miniaturized slotted Jerusalem Cross (JC) Artificial Magnetic Conductor (AMC) ground plane. The AMC ground plane is utilized to isolate the user's body from undesired electromagnetic radiation in addition to minimizing the antenna's impedance mismatch caused by the proximity to human tissues. Specific Absorption Rate (SAR) is analyzed using a numerical human body model (HUGO) to assess the feasibility of the proposed design. The antenna expresses 18% impedance bandwidth; moreover, the inclusion of the AMC ground plane increases the front to back ratio by 8 dB, provides 3.7 dB increase in gain, in addition to 64% reduction in SAR. Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas. Furthermore, it offers a compact and flexible solution which makes it a good candidate for the wearable telemedicine application.

This paper investigates the effects of bending on the performance of a flexible dual-band printed monopole antenna designed to work for GPS, WLAN, and WiMAX applications. The antenna is printed on a Polyimide substrate with a relative permittivity of 4.3 and thickness of 25 pm. The antenna is fed by a coplanar waveguide transmission line to enhance the impedance matching over the wide operating bandwidth. The dual bands are (1.53–1.67) GHz and (2.95–5.8) GHz. The simulated and measured values are in good agreement in term of Sn before and after bending. The radiation patterns show excellent performance of the antenna in the applications under consideration. The antenna achieves a maximum gain of 2 dB over the first band and 3.6 dB over the second band.

The effects of thickness and dielectric constant of flexible substrates on the performance of a circular planar monopole antenna (PMA) is reported in this paper. The antenna is printed on a flexible Polyimide substrate and fed by 50 Ω microstrip line. Results revealed that substantial effect on the antenna performance due to substrate thickness and material even if the radiating structure is ungrounded. Hence, the substrate is an essential part of the antenna and not just a supporting structure as it is the case usually assumed in the literature. As substrate thickness decreases, the following changes were observed: reduction in impedance bandwidth especially for higher dielectric constants, and slight increase in the co-polarized gain. As the dielectric constant increases the following effects were identified: the impedance bandwidth increased on the high frequencies side while it is insignificant on the lower frequencies, as well as a decreased in the co-polarized gain.

In this article, a miniaturized dual band, multislotted bow-tie microstrip antenna for wearable telemedicine applications involving a bidirectional wireless link between implantable and wearable systems is proposed. The number, size, and position of the slots, center width, as well as the size of the ground plane, were selected to control the TM30 mode such that the antenna resonates at the desired frequencies and provides the radiation patterns for the intended application. The antenna operates with a dipole-like radiation pattern in the 915 MHz band and a broadside radiation pattern in the 2.45 GHz band. The reflection coefficient and far-field radiation patterns were measured and compared against the simulated results. V C 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:365-369, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/ mop.26523

In this paper, we present a miniaturized Truncated Sinusoidal Printed Circuit Antenna (TSPCA) consisting of a thin conductive film of copper mounted on a flexible substrate for wearable biomedical telemetry and smart clothes applications on the premises of health care and sport medicine facilities. The fundamental resonant mode of the proposed TSPCA is 611 MHz. The flat antenna operates over the frequency range from 608 to 614 MHz (−10 dB return-loss bandwidth of 1.7%) with a bore-sight gain of −29 dBi when operating in a free-space environment. The antenna size has been miniaturized to a 10 mm × 10 mm × 0.5 mm using a shorting plate on a substrate with a relative permittivity of 6.15 and loss tangent of 0.00134. The effects of twisting and bending on the performance of the TSPCA are investigated. It has been found that the maximum change in bore-sight gain, resonant frequency, and S11, with respect to the flat case, is −8.5 dBi, 0.2%, and −4 dB, respectively, with respect to the flat case for bend angles ranging from −45° to 45°. Twisting of the antenna, on the other hand, in the range from −45° to 45° showed a maximum change of −16 dBi, 1%, and −17 dB in the bore-sight gain, resonant frequency, and S11, respectively. The bandwidth remains virtually unaffected for both cases. The performance of the TSPCA is investigated when the antenna is mounted parallel to and at a distance of 0.5 mm from the arm, leg, thigh, and head. It has been found that maximum change in bore-sight gain, resonant frequency, and S11 is −3.5 dBi, 2.5%, and −6.5 dB, respectively with respect to the isolated antenna.

Recent demands for miniaturized, lightweight, high data rate, and reliable wireless devices motivated researches and designers of wireless systems to adopt the use of multiple input-multiple output MIMO antenna arrays with close proximity of each other. One of the difficulties is to overcome the problems associated with the low isolation between any two closely spaced antennas. The low profile, small size, ease of fabrication, and simplicity of design encourage the use of the IFA/PIFA antennas. In this paper, two vertical IFA antennas with close separation of λ o /15 ( o /2) fed by coaxial lines are combined in an array operating at the frequency of 2.5 GHz. The two antennas are deployed on a ground backed substrate of 50 mm × 50 mm in length and width respectively and a thickness of 1.524 mm with a relative permittivity, e r of 10.2. Each IFA consists of a monopole as the main radiator with a length of 38 mm and a diameter of 1.22 mm placed 11 mm above the ground plane. The separation between the feeding point and the grounded end of the radiating element is 10 mm. The consequence of positioning the antenna in the proximity of each other is the high mutual coupling. To decrease the resulted effects, a new Defected Ground Structure (DGS) has been proposed. A rectangular slot of 32 mm and width of 1.5 mm with a strip line of 29 mm in length and a width of 1 mm have been introduced to the ground plane. The final proposed array with the DGS is shown in the attached figure. The Defected Ground Structure (DGS) has the effect of reducing the interaction between the antennas, main radiators, by restricting the current flow in the ground plane. A parametric study has been carried out to obtain the optimum dimensions of the structure using Ansys High Frequency Structure Simulator (HFSS). The S-Parameters of the design are shown in the enclosed figure. The antenna has an operating frequency of 2.5 GHz. A total isolation level of -22 dB has been achieved by the proposed structure at the operating frequency. The array with the proposed ground structure provides a gain of 3.9 dB at 2.5 GHz when the two ports are excited. This structure is a good candidate for reducing the mutual coupling between two vertical IFA for application utilizing MIMO techniques.

This paper presents a mutual reduction technique based on the insertion of two strips between two adjacent planar monopole rectangular patch antennas with an edge to edge separation of λ o /31. The array achieves a total realized gain of 3.73, 4.39 and 3.84 dB at 1.85, 2.4, and 3.5 GHz respectively, a relative bandwidth of 69% (1.8 – 3.7) GHz over which the matching level |S 11 | is less than −10 dB and the coupling level |S 21 | is below or equal to −20 dB. The performance offered by the proposed design represents a good candidate to be implemented in modern wireless standards including 3GPP LTE, WiMAX, and IEEE 802.11 WLAN and systems utilizing the ISM band.

This paper presents a planar slotted meander line structure to reduce the mutual coupling between two microstrip fed planar monopole patch antennas. The array provides a relative operating bandwidth of 98 % (1.37–4.00) GHz matched at a reflection coefficient S11 and S22 less than −10 dB with a total realized gain of 3.9, 4.66, and 4 dB at 1.85, 2.4, and 3.5 GHz respectively. The isolation level has been reduced to less than −20 dB for a wide frequency band of 85 % (1.46–3.64) GHz. The design represents a good candidate for modern wireless standards utilizing MIMO techniques including 3GPP LTE, WiMAX, WiFi, as well as systems utilizing ISM spectrum equipped with multiple antennas.

Until recently, the UWB antenna has been used in many applications within different areas such in medical applications, multimedia connectivity, and personal communications, to mention a few, due to the design simplicity, low power, and high data rate transmission. The monopole antenna is a good candidate to be used in such applications due to the compact size, simplicity of fabrication, and cost effectiveness. Furthermore, the wearable devices technology requires a small size, high efficiency, and low profile antennas. An elliptical ring monopole antenna of 46 mm major axis and 23 mm minor axis printed on a Kapton substrate with a length of 66 mm, width of 36 mm, and a thickness of 50.8-µm is a good candidate to operate for the DSC (1.61 – 2) GHz and UWB (3.1 – 10.6) GHz bands. Two square slots of 2mm × 2mm have been removed from the two edge of the ground plane to enhance the impedance matching over the frequency range of (8–11) GHz. This antenna is fed by a tapered coplanar waved guide (CPW) transmission line of 12.8 mm length with a gap of 0.4mm to provide an enhanced impedance matching of 50 ohm over the aforementioned bands(H. Khaleel, H. Al-Rizzo, D. Rucker, S. Mohan, Antennas and Wireless Propagation Letters, IEEE, vol.11, no., pp.564–567, 2012). In addition, a modified rectangular slot line has been inserted to the monopole antenna to provide a notch at the frequency of 5.8 GHz to reject the signal comes from WLAN applications which operating at the given frequency. This slot line is able to be adjusted to any specified frequency that would be rejected. These types of antennas are very useful these days for the application that required a rejection of the unwanted frequencies especially for UWB applications. The antenna has been simulated using the High Frequency Structure Simulator (HFSS) ver. 15 and fabricated using an Inkjet printer. A parametric study has been carried out to obtain the final antenna dimensions which are mentioned on the attached figure. The simulated and practical S-Parameters are in a good agreement and shown in the figure below. The antenna has a good gain and radiation characteristic over the specified bandwidths. The proposed antenna is a good candidate for the applications required antennas operates on a DSC and UWB bands with a tunable band rejection.

This paper presents a simple yet very effective decoupling mechanism based on the insertion of two adjacent planar monopole rectangular patch antennas separated by λ o /62. The array achieves a total realized gain of 3.48 dB (exciting one port) and 4.78 dB (exciting two ports), a relative bandwidth of 49 % ( 2 – 3.3 ) GHz over which the matching level |S 21 | is less than −10 dB and a coupling level |S 21 | is below or equal to −20 dB. The antenna array offers radiation pattern diversity for different port excitation situation. The gain, decoupling level, radiation pattern diversity, and relatively compact size offered by the proposed antenna provides a good candidate to be implemented in modern wireless communication devices including, but not limited to, systems utilizing the ISM band.

In this letter, we present the performance of a typical artificial magnetic conductor (AMC) under different bending extents. Square patch array-based AMC is employed as a benchmark to demonstrate the dependence of AMC characteristics on the degree of curvature. We show that increasing the extent of bending leads to a shift to a higher resonance frequency and bandwidth degradation which suggests the importance of such analysis when designing AMC structures for conformal applications. Finite element method full wave electromagnetic solver has been employed to extract the reflection phase profile of the structure under study. To the best of the authors' knowledge, this kind of study is being reported for the first time. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2503–2505, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27124

Electromagnetic interference effects caused by electric power lines on neighboring metallic utilities such as water, gas or oil pipelines became a major concern due tosignificant increase in the load and short circuit current levels needed to satisfy the load requirements. Another reason for increased interference levels originates from the environmental concerns, which impose on various utilities the obligation to share common corridors. This paper presents three different scenarios of a pipeline in which all types of electromagnetic interferences (coupling) will be investigated and their effects on the pipeline will be predicted. The level of the calculated voltage, owing to each type of coupling, depends on different factors (voltage level, length of parallelism, separation distance, soil resistivity, load current magnitude and pipeline coating). The effects of these factors are discussed; some factors such as the fault current level, separation distance and soil resistivities are found to exhibit a large influence on the pipeline voltage. To the best of the authors’ knowledge, the comprehensive analyses presented in this paper considering all types of interferences have not yet been publishedelsewhere.

A great deal of attention has been focused recently towards the development and optimization of Ultra Wide Band (UWB) wireless systems due to their outstanding features which include: low power requirement, configuration simplicity, and very high data rate. This technology can be deployed in a wide spectrum of fields such as: medical devices, entertainment and multimedia connectivity, and personal communication. For most modern consumer devices, WiFi connectivity is required. Hence, the antenna is required to have an omnidirectional radiation characteristics. A printed monopole antennas would serve as a good candidate for such systems due to its compactness, high efficiency, simple fabrication process, and cost effectiveness. Moreover, the emerging wearable electronics technology require low profile, light weight and compact antennas.

The capability of bending, twisting and folding offered by mechanically flexible films and/or substrates along with size, weight and cost constraints are among the main challenges in future wearable electronic devices. In this paper, the effects of bending on a planar flexible CPW- IFA antenna operating at WLAN (IEEE 802.11) 2.4/5.2/5.8 GHz bandwidths is proposed. The flat antenna achieves a relative bandwidth of 14% (2.25-2.61) GHz and 42% (4.98-7.64) GHz over which S11 is less than -10 dB, and a realized gain of 1.86, 4.21 and 2.94 dB at 2.4, 5.2, and 5.8, respectively. The results show that the antenna maintained the WLAN matching lower and upper bandwidths required under a wide range of bending angles ψB.

A compact Ultra Wide Band (UWB) antenna printed on a 50.8-μm Kapton polyimide Substrate is proposed in this paper. The semi-eliptical based radiating element is fed by a linearly tapered coplanar waveguide (CPW) which provides continuous transitional impedance for improved matching. The proposed design covers the standard UWB range which extends between 3.1 to 10.6 GHz. Furthermore, a T shaped structure is added to give rise to a resonance at 2.45 GHz which encompasses the Industrial, Scientific, Medical (ISM) band.

Their light weight, low-cost manufacturing, ease of fabrication, and the availability of inex‐ pensive flexible substrates (i.e.: papers, textiles, and plastics) make flexible electronics an ap‐ pealing candidate for the next generation of consumer electronics [2]. Moreover, recent developments in miniaturized and flexible energy storage and self-powered wireless com‐ ponents paved the road for the commercialization of such systems [3].

In this paper, a miniaturized microstrip antenna array with two patches is proposed for wearable MIMO systems. The array is designed to resonate at 4.2 GHz and 8.1 GHz for biomedical micro-sensing technology and biomedical diagnostics applications, respectively. In this paper, the use of a diagonal slot on the microstrip patch to reflect the surface current in a direction opposite to that of the neighboring patch. Moreover, the common area of the ground plane, between the two antennas, is augmented with Uniform Compact-Photonic Band Gap (UC-PBG) structures to prevent surface waves. This approach reduces the mutual coupling to −17 dB within a separation distance of 1.4 mm ≈ λ o /51, where λ o is the wavelength at 4.2 GHz. The microstrip antenna patch is consistent of rectangular part slotted with a diagonal trace and a meander trace which reduces the electrical size of the microstrip patch, when it is printed on substrate of e r = 3.5, to λ o /18 × λ o /5. The maximum linear dimension of the antenna array is λ o /7.2 × λ o /4.3 × λ o /137. The performance of the array is characterized in terms of S-parameters, broadband gain and correlation spectra as well as the radiation patterns. The proposed antenna array provides bore-sight gain of −15.1 dBi at 4.2 GHz and −7.5 dBi at 8.1 GHz of 54.2 MHz and 81.8 MHz, respectively. The numerical model of the proposed array is simulated based on the Finite Integration Technique (FIT) using the Transient Domain (TD) solver of CST Microwave Studio.

In this paper, we present two thin/flexible printed monopole antennas for Wireless Local Area Network (WLAN) applications. The first design is a single band antenna which operates at 2.4 GHz while the second one is a dual band antenna operates at 2.5 GHz and 5.2 GHz. The dimensions of the proposed antennas are: (26.5 mm × 25) and (35 mm × 25) mm for the single band and dual band respectively. Antenna properties, such as gain, far-field radiation patterns, coupling coefficient, expressed in terms of the scattering parameter S11 are provided. Design and simulations are performed using CST Microwave Studio software which is based on the Finite Integration Technique (FIT). Moreover, the effect of folding the antenna was performed experimentally on both designs to study its influence on the antenna performance. The achieved gain for the single band antenna is 1.8 dB with a measured bandwidth of 270 MHz. The dual band antenna achieved a gain of 1.8 dB and 4 dB at 2.5 GHz and 5.2 GHz respectively, and measured bandwidths of 305 MHz and 480 MHz at the first and second band respectively. The proposed thin and flexible designs along with antennas characteristics are suitable for integration into flexible technologies for WLAN applications.

Flexible microstrip antenna arrays have become a necessity in today’s miniaturized biomedical wireless devices. Implantable and wearable biomedical devices such as pacemakers, drug delivery systems, heart rate monitors, and respiratory monitors need to communicate with exterior base station devices and relayed to healthcare professionals. In this paper, multiple flexible microstrip antenna arrays are designed and simulated for these applications. The frequency bands of 5.2 GHz and 5.8 GHz are utilized to provide a high bandwidth communication link. CST Microwave Studio was used for the modeling and simulation of the antennas. The reflection coefficient, gain, and correlation coefficient for each antenna are presented and discussed. The presented antennas can be utilized together as an array for enhanced gain or independently in a Multiple Input Multiple Output (MIMO) system.

In this paper, a miniaturized microstrip antenna design is presented for establishing wireless communications with implantable medical devices in the 402--405 MHz Medical Implant Communications Services (MICS). The Ansoft's High Frequency Structure Simulator (HFSS) and CST Microwave Studio were used to evaluate the antenna design. HFSS is based on the Finite Element Method (FEM) and Microwave Studio is based on the Finite Difference Time Domain (FDTD) technique. The results from both simulations are compared to validate results obtained from the two software packages. A varactor diode is added to allow tuning of the antenna. Size reduction techniques such as meandering, addition of a shorting pin, and the introduction of a capacitive plate were investigated to make the antenna size suitable for use with medical implants.