scispace - formally typeset
Search or ask a question

Showing papers in "International Journal of Antennas and Propagation in 2013"


Journal ArticleDOI
TL;DR: In this paper, a comparative analysis of various reconfigurable and multiband antenna concepts is presented, which can be classified into three basic approaches: tunable/switchable antenna integration with radio-frequency switching devices, wideband or multiband antennas integration with tunable filters, and array architectures with the same aperture utilized for different operational modes.
Abstract: A comparative analysis of various reconfigurable andmultiband antenna concepts is presented. In order to satisfy the requirements for the advanced systems used in modern wireless and radar applications, different multiband and reconfigurable antennas have been proposed and investigated in the past years. In this paper, these design concepts have been classified into three basic approaches: tunable/switchable antenna integration with radio-frequency switching devices, wideband or multiband antenna integration with tunable filters, and array architectures with the same aperture utilized for different operational modes. Examples of each design approach are discussed along with their inherent benefits and challenges.

140 citations


Journal ArticleDOI
TL;DR: A description of the evolution of wireless handheld devices, regulations, challenges in today’s smartphones, and handset characterization is reviewed and recent advances in antenna technology for wireless handheld or portable devices are presented.
Abstract: The constant evolution of wireless handheld devices together with the apparition of multiple wireless communication systems fosters the antenna community to design new radiating and measurements systems capable of satisfying the market demands. It is an object of the present paper to provide an overview of the evolution that wireless handheld technology has experienced in the last years. In this sense, a description of the evolution of wireless handheld devices, regulations, challenges in today’s smartphones, and handset characterization is reviewed. Finally, recent advances in antenna technology for wireless handheld or portable devices are presented.

140 citations


Journal ArticleDOI
TL;DR: In this article, a printed reconfigurable ultra-wideband (UWB) monopole antenna with triple narrow band-notched characteristics is proposed for cognitive radio applications, which can work at eight modes by controlling switches ON and OFF.
Abstract: A printed reconfigurable ultra-wideband (UWB) monopole antenna with triple narrow band-notched characteristics is proposed for cognitive radio applications in this paper. The triple narrow band-notched frequencies are obtained using a defected microstrip structure (DMS) band stop filter (BSF) embedded in the microstrip feed line and an inverted π-shaped slot etched in the rectangular radiation patch, respectively. Reconfigurable characteristics of the proposed cognitive radio antenna (CRA) are achieved by means of four ideal switches integrated on the DMS-BSF and the inverted π-shaped slot. The proposed UWB CRA can work at eight modes by controlling switches ON and OFF. Moreover, impedance bandwidth, design procedures, and radiation patterns are presented for analysis and explanation of this antenna. The designed antenna operates over the frequency band between 3.1 GHz and 14 GHz (bandwidth of 127.5%), with three notched bands from 4.2 GHz to 6.2 GHz (38.5%), 6.6 GHz to 7.0 GHz (6%), and 12.2 GHz to 14 GHz (13.7%). The antenna is successfully simulated, fabricated, and measured. The results show that it has wide impedance bandwidth, multimodes characteristics, stable gain, and omnidirectional radiation patterns.

119 citations


Journal ArticleDOI
TL;DR: In this article, a comprehensive review of the methods that model and mitigate the mutual coupling effect for different types of arrays is discussed, and the techniques for optimization of the antenna characteristics in the presence of coupling are also included.
Abstract: The mutual coupling between antenna elements affects the antenna parameters like terminal impedances, reflection coefficients and hence the antenna array performance in terms of radiation characteristics, output signal-to-interference noise ratio (SINR), and radar cross section (RCS). This coupling effect is also known to directly or indirectly influence the steady state and transient response, the resolution capability, interference rejection, and direction-of-arrival (DOA) estimation competence of the array. Researchers have proposed several techniques and designs for optimal performance of phased array in a given signal environment, counteracting the coupling effect. This paper presents a comprehensive review of the methods that model and mitigate the mutual coupling effect for different types of arrays. The parameters that get affected due to the presence of coupling thereby degrading the array performance are discussed. The techniques for optimization of the antenna characteristics in the presence of coupling are also included.

116 citations


Journal ArticleDOI
TL;DR: In this paper, microstrip patch structured rectennas are evaluated and compared with an emphasis on the various methods adopted to obtain a compact rectenna, harmonic rejection functionality, and frequency and polarization selectivity.
Abstract: In the last few years, several antenna designs of rectenna that meet various objectives have been proposed for use in RF energy harvesting. Among various antennas, microstrip patch antennas are widely used because of their low profile, light weight, and planar structure. Conventional patch antennas are rectangular or circular in shape, but variations in their basic design are made for different purposes. This paper begins with an explanation and discussion of different designs, put forward with an aim of miniaturization, harmonic rejection, and reconfigurability. Finally, microstrip patch structured rectennas are evaluated and compared with an emphasis on the various methods adopted to obtain a compact rectenna, harmonic rejection functionality, and frequency and polarization selectivity.

96 citations


Journal ArticleDOI
TL;DR: A comprehensive review on various EBG structures such as three-, two-, and one-dimensional (3D, 2D, and 1D) EBG, mushroom and uniplanar EBG is provided in this paper.
Abstract: Electromagnetic band gap (EBG) technology has become a significant breakthrough in the radio frequency (RF) and microwave applications due to their unique band gap characteristics at certain frequency ranges. Since 1999, the EBG structures have been investigated for improving performances of numerous RF and microwave devices utilizing the surface wave suppression and the artificial magnetic conductor (AMC) properties of these special type metamaterial. Issues such as compactness, wide bandwidth with low attenuation level, tunability, and suitability with planar circuitry all play an important role in the design of EBG structures. Remarkable efforts have been undertaken for the development of EBG structures to be compatible with a wide range of wireless communication systems. This paper provides a comprehensive review on various EBG structures such as three-, two-, and one-dimensional (3D, 2D, and 1D) EBG, mushroom and uniplanar EBG, and their successive advancement. Considering the related fabrication complexities, implementation of vialess EBG is an attractive topic for microwave engineers. For microstrip antennas, EBG structures are used in diversified ways, which of course found to be effective except in some cases. The EBG structures are also successfully utilized in antenna arrays for reducing the mutual coupling between elements of the array. Current challenges and limitations of the typical microstrip antennas and different EBG structures are discussed in details with some possible suggestions. Hopefully, this survey will guide to increasing efforts towards the development of more compact, wideband, and high-efficient uniplanar EBG structures for performance enhancement of antenna and other microwave devices.

83 citations


Journal ArticleDOI
TL;DR: The potential of liquid crystals as reconfigurable materials arises from their ability for continuous tuning with low power consumption, transparency, and possible integration with printed and flexible circuit technologies as discussed by the authors.
Abstract: An overview of liquid crystal technology for microwave and millimeter-wave frequencies is presented. The potential of liquid crystals as reconfigurable materials arises from their ability for continuous tuning with low power consumption, transparency, and possible integration with printed and flexible circuit technologies. This paper describes physical theory and fundamental electrical properties arising from the anisotropy of liquid crystals and overviews selected realized liquid crystal devices, throughout four main categories: resonators and filters, phase shifters and delay lines, antennas, and, finally, frequency-selective surfaces and metamaterials.

79 citations


Journal ArticleDOI
Changjiang Deng1, Wenhua Chen1, Zhijun Zhang1, Yue Li1, Zhenghe Feng1 
TL;DR: In this paper, the authors proposed a feasible and simple solution of generating OAM-carrying radio beams by changing the phase difference at the steps of 0, ±45°, ±90° and ±135°, and 180°.
Abstract: This paper gives a feasible and simple solution of generating OAM-carrying radio beams. Eight Vivaldi antenna elements connect sequentially and fold into a hollow cylinder. The circular Vivaldi antenna array is fed with unit amplitude but with a successive phase difference from element to element. By changing the phase difference at the steps of 0, ±45°, ±90°, ±135°, and 180°, the OAM radio beam can be generated with mode numbers 0, ±1, ±2, ±3, and 4. Simulations show that the OAM states of ±2 and ±3 are the same as the traditional states, while the OAM states of 0, ±1, and 4 differ at the boresight. This phenomenon can be explained by the radiation pattern difference between Vivaldi antenna and tripole antenna. A solution of distinguishing OAM states is also proposed. The mode number of OAM can be distinguished with only 2 receivers.

74 citations


Journal ArticleDOI
TL;DR: In this article, a wearable low-profile inset-fed quarter-wave folded microstrip patch antenna for noninvasive activity monitoring of elderly is presented, embedded with a sensor-enabled passive radio-frequency identification (RFID) tag operating in the ultra-high frequency (UHF) industrial-scientific-medical (ISM) band around 900 MHz.
Abstract: A wearable low-profile inset-fed quarter-wave folded microstrip patch antenna for noninvasive activity monitoring of elderly is presented. The proposed antenna is embedded with a sensor-enabled passive radio-frequency identification (RFID) tag operating in the ultra-high frequency (UHF) industrial-scientific-medical (ISM) band around 900 MHz. The device exhibits a low and narrow profile based on a planar folded quarter-wave length patch structure and is integrated on a flexible substrate to maximise comfort to the wearer. An extended ground plane made from silver fabric successfully minimises the impact of the human body on the antenna performance. Measurements on a prototype demonstrate a reflection coefficient () of −30 dB at resonance and a −10 dB bandwidth from 920 MHz to 926 MHz. Simulation results predict a maximum gain of 2.8 dBi. This is confirmed by tag measurements where a 4-meter read range is achieved using a transmit power of 30 dBm, for the case where the passive wearable tag antenna is mounted on a body in a practical setting. This represents an almost 40% increase in read range over an existing dipole antenna placed over a 10 mm isolator layer on a human subject.

61 citations


Journal ArticleDOI
TL;DR: This paper provides a comprehensive survey focused on the performance of adopted beamforming technique on MIMO relay networks that is expected to overcome crucial obstacles in terms of capacity and interference.
Abstract: One of the major challenges the mobile broadband community faces is the exponential increase in mobile data traffic, even more so, for cell-edge users. Thus, in a multitier network, the demand for high-speed and interference-free transmission and reception is inevitable. Beamforming (BF) is an advanced technology that offers a significantly improved solution to reduce the interference levels and improve the system capacity. Accordingly, the establishment of relays in mobile data networks has emerged spectral efficiency enhancements and cell capacity gains from an overall system perspective. This paper provides a comprehensive survey focused on the performance of adopted beamforming technique on MIMO relay networks that is expected to overcome crucial obstacles in terms of capacity and interference. The main objective is to point out the state-of-the-art research activity on BF techniques in MIMO relay networks, under various network performance challenges. Thereby, it focuses on recently developed procedures for interference modeling and mitigation, BF channel modeling, channel estimation and feedback, complexity and power consumption, adaptive BF for multiuser relaying, degrees of freedom, diversity issues, and spectral efficiency, in cooperative and opportunistic systems. Different network topologies have been considered and categorized, pertaining the challenges of BF implementation in MIMO relay networks.

55 citations


Journal ArticleDOI
Fengyu Luan1, Yan Zhang1, Limin Xiao1, Chunhui Zhou1, Shidong Zhou1 
TL;DR: This paper focuses on the fading characteristics of wireless channel on High-Speed Railway (HSR) in hilly terrain scenario and measures and modelled the fading parameters, including path loss, shadow fading, and K-factor.
Abstract: This paper focuses on the fading characteristics of wireless channel on High-Speed Railway (HSR) in hilly terrain scenario. Due to the rapid speed, the fading characteristics of HSR channel are highly correlated with time or Transmit-Receive distance and have their own special property. To investigate the fading characteristics, the measurement is conducted on the Guangzhou-Shenzhen passenger-dedicated line in China with the speed of 295 km/h in the data-collection area at 2.4 GHz. From the measured data, the amplitude of each path is estimated by using the Subspace-Alternating Generalized Expectation-Maximization (SAGE) algorithm along with other parameters of channel impulse responses. Then the fading parameters, including path loss, shadow fading, and K-factor, are analysed. With the numerical results in the measurement and analysis, the fading characteristics have been revealed and modelled. It is supposed that this work has a promotion for HSR communication system design and improvement.

Journal ArticleDOI
TL;DR: In this article, an innovative gapless traceability system is presented to improve the main business processes of the fresh vegetables supply chain, from the land to the table of the end consumer, and allowed us to reengineer the most important processes.
Abstract: The paper presents an innovative gapless traceability system able to improve the main business processes of the fresh vegetables supply chain. The performed analysis highlighted some critical aspects in the management of the whole supply chain, from the land to the table of the end consumer, and allowed us to reengineer the most important processes. In particular, the first steps of the supply chain, which include cultivation in greenhouses and manufacturing of packaged vegetables, were analyzed. The re-engineered model was designed by exploiting the potentialities derived from the combined use of innovative Radio Frequency technologies, such as RFID and NFC, and important international standards, such as EPCglobal. The proposed tracing and tracking system allows the end consumer to know the complete history of the purchased product. Furthermore, in order to evaluate the potential benefits of the reengineered processes in a real supply chain, a pilot project was implemented in an Italian food company, which produces ready-to-eat vegetables, known as IV gamma products. Finally, some important metrics have been chosen to carry out the analysis of the potential benefits derived from the use of the re-engineered model.

Journal ArticleDOI
TL;DR: The paper considers the better and more similar human head model and compares these two models, and shows that the initial model (one layer) is not a good model, because the real human head tissue is not equivalently modeled.
Abstract: The interaction between human head model and electromagnetic field sources is studied. The head models are composed of one and six layers. The six layers are skin, fat, bone, dura (the outer membrane of brain and spinal cord), CSF (colony stimulating factor), and brain. An antenna as a source of exposure is simulated too. The E-field strength distribution in both one- and six-layer human models is shown to estimate the intensity of E-field penetration in human head. Like standard models, the antenna is situated near the head model at a distance of 5 mm. The local and average SARs (specific absorption rates) are simulated at 900 MHz in both human head models. The results are then compared between the two models. The HFSS software is used for all the simulations. The paper wants to show that the initial model (one layer) is not a good model, because the real human head tissue is not equivalently modeled. It seems that the values of one-layer model are not reliable, so the paper considers the better and more similar human head model and compares these two models.

Journal ArticleDOI
TL;DR: In this paper, a temperature monitoring solution at the box level in the fish supply chain is presented as part of the traceability system implemented with RFID technology, where RFID data loggers are placed inside the box to measure the temperature of the product and on the box for measuring ambient temperature.
Abstract: Radio frequency identification (RFID) is an innovative and well-recognized technology that supports all kinds of traceability systems in many areas. It becomes very important in the food industry where the electronic systems are used to capture the data in the supply chain. Additionally, RFID data loggers with sensors are available to perform a cold chain optimization for perishable foods. This paper presents the temperature monitoring solution at the box level in the fish supply chain as part of the traceability system implemented with RFID technology. RFID data loggers are placed inside the box to measure the temperature of the product and on the box for measuring ambient temperature. The results show that the system is very helpful during the phases of storage and transportation of fish to provide the quality control. The sensor data is available immediately at the delivery to be checked on the mobile RFID reader and afterwards stored in the traceability systems database to be presented on a web to stakeholders and private consumers.

Journal ArticleDOI
TL;DR: In this paper, the characteristics of directivity enhancement using different metamaterial structures as antenna superstrates, such as electromagnetic bandgap (EBG) structures, frequency selective surface (FSS), and left-handed material (LHM), are unifiedly studied by applying the theory of Fabry-Perot (F-P) resonant cavity.
Abstract: Metamaterial superstrate is a significant method to obtain high directivity of one or a few antennas. In this paper, the characteristics of directivity enhancement using different metamaterial structures as antenna superstrates, such as electromagnetic bandgap (EBG) structures, frequency selective surface (FSS), and left-handed material (LHM), are unifiedly studied by applying the theory of Fabry-Perot (F-P) resonant cavity. Focusing on the analysis of reflection phase and magnitude of superstrates in presently proposed designs, the essential reason for high-directivity antenna with different superstrates can be revealed in terms of the F-P resonant theory. Furthermore, a new design of the optimum reflection coefficient of superstrates for the maximum antenna directivity is proposed and validated. The optimum location of the LHM superstrate which is based on a refractive lens model can be determined by the F-P resonant distance.

Journal ArticleDOI
TL;DR: In this article, the experimental testing of effective probe compensated near-field-far-field (NF-FF) transformations with spherical scanning requiring a minimum number of NF data is presented.
Abstract: This paper deals with the experimental testing of effective probe compensated near-field-far-field (NF-FF) transformations with spherical scanning requiring a minimum number of NF data. They rely on nonredundant sampling representations of the voltage measured by the probe, based on very flexible source modellings suitable for nonvolumetric antennas characterized by two dimensions very different from the other one. In particular, a cylinder ended in two half-spheres is adopted for modelling long antennas, whereas the quasi-planar ones are considered as enclosed in a rotational surface formed by two circular “bowls” having the same aperture diameter, but eventually different bending radii. The NF data needed to perform the classical spherical NF-FF transformation are then accurately and efficiently retrieved from the acquired nonredundant ones via optimal sampling interpolation formulas. A remarkable reduction of the number of the required NF data and, as a consequence, a significant measurement time saving can be so obtained. The experimental tests have been carried out at Antenna Characterization Lab of the University of Salerno and both the NF and FF reconstructions are resulted to be very good, thus confirming the accuracy and reliability of these NF-FF transformations from the experimental viewpoint too.

Journal ArticleDOI
TL;DR: In this paper, a dynamic beamforming algorithm is proposed where vertical domain of antenna is fully considered and beamforming vector can be obtained according to UEs' horizontal and vertical directions.
Abstract: MIMO system with large number of antennas, referred to as large MIMO or massive MIMO, has drawn increased attention as they enable significant throughput and coverage improvement in LTE-Advanced networks. However, deploying huge number of antennas in both transmitters and receivers was a great challenge in the past few years. Three-dimensional MIMO (3D MIMO) is introduced as a promising technique in massive MIMO networks to enhance the cellular performance by deploying antenna elements in both horizontal and vertical dimensions. Radio propagation of user equipments (UE) is considered only in horizontal domain by applying 2D beamforming. In this paper, a dynamic beamforming algorithm is proposed where vertical domain of antenna is fully considered and beamforming vector can be obtained according to UEs’ horizontal and vertical directions. Compared with the conventional 2D beamforming algorithm, throughput of cell edge UEs and cell center UEs can be improved by the proposed algorithm. System level simulation is performed to evaluate the proposed algorithm. In addition, the impacts of downtilt and intersite distance (ISD) on spectral efficiency and cell coverage are explored.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the impact of additional power load on the RFID system proper operation and the size of interrogation zone on the LTCC pressure sensor in the presence of RFID transponders.
Abstract: The huge progress in electronics technology and RFID technique gives the opportunity to implement additional features in transponders. It should be noted that either passive or semipassive transponders are supplied with energy that is derived from the electromagnetic field generated by the read/write device and its antenna. This power source is used to conduct radio-communication process and excess energy could be used to power the extra electronic circuits, but the problem is to determine the additional power load impact on the RFID system proper operation and size of interrogation zone. The ability to power the supplementary electronic blocks applied in the HF passive transponders is discussed in detail this paper. The simulation model and test samples with a harvester that recovers energy from the electromagnetic field of read/write device and its antenna have been developed in order to conduct investigations. The harvested energy has been utilized to supply a microprocessor acquisition block for LTCC pressure sensor developed in research previously described by authors.

Journal ArticleDOI
TL;DR: In this paper, a dual-band on-body repeater antenna for in-on-on wireless body area network applications is proposed, which has a maximum radiation normal to the human-body surface for communication with implanted devices in the 5.8 GHz industrial, scientific, and medical (ISM) band.
Abstract: A dual-band on-body repeater antenna for in-on-on wireless body area network applications is proposed. The proposed antenna has a maximum radiation normal to the human-body surface for communication with implanted devices in the 5.8 GHz industrial, scientific, and medical (ISM) band. In addition, to transmit the biological information received from the implanted devices to other on-body devices, the proposed antenna was designed to have a monopole-like radiation pattern along the surface of the human body for communication in the 2.45 GHz ISM band. The antenna was fabricated, and its performance was measured by attaching it to a human-equivalent semisolid phantom. In addition, the human-body effect was studied to ensure antenna performance under an actual situation.

Journal ArticleDOI
Xin Su, Jie Zeng, Jingyu Li1, Liping Rong, Liu Lili, Xibin Xu, Jing Wang 
TL;DR: This paper proposes a new avenue of codebook design based on a Kronecker-type approximation of the array correlation structure for the uniform rectangular antenna array, which is preferable for the antenna deployment of massive MIMO.
Abstract: The large-scale array antenna system with numerous low-power antennas deployed at the base station, also known as massive multiple-input multiple-output (MIMO), can provide a plethora of advantages over the classical array antenna system. Precoding is important to exploit massive MIMO performance, and codebook design is crucial due to the limited feedback channel. In this paper, we propose a new avenue of codebook design based on a Kronecker-type approximation of the array correlation structure for the uniform rectangular antenna array, which is preferable for the antenna deployment of massive MIMO. Although the feedback overhead is quite limited, the codebook design can provide an effective solution to support multiple users in different scenarios. Simulation results demonstrate that our proposed codebook outperforms the previously known codebooks remarkably.

Journal ArticleDOI
TL;DR: In this paper, small displacement detection has been studied for extracting heart rate signal from the respiratory variation component of the human body with the FMCW radar method and a new signal processing method of vital signal has been proposed for suppression of unrequired variation components called projection matrix method.
Abstract: Small displacement detection has been studied for extracting heart rate signal from the respiratory variation component of the human body with the FMCW radar method. And a new signal processing method of vital signal has been proposed for suppression of unrequired variation components called projection matrix method. We have presented experimental results of small displacement detection to confirm the validity of the method.

Journal ArticleDOI
TL;DR: This tutorial paper points out several viewpoints which are relevant in this context: the restrictions and the potential provided by different array configurations, the predictability of the transmission function of the array, the constraints for adaptive beamforming, the inclusion of monopulse, detection and tracking into the adaptive beamform concept, and the assessment of superresolution methods with respect to their application in a radar system.
Abstract: Array processing for radar is well established in the literature, but only few of these algorithms have been implemented in real systems. The reason may be that the impact of these algorithms on the overall system must be well understood. For a successful implementation of array processing methods exploiting the full potential, the desired radar task has to be considered and all processing necessary for this task has to be eventually adapted. In this tutorial paper, we point out several viewpoints which are relevant in this context: the restrictions and the potential provided by different array configurations, the predictability of the transmission function of the array, the constraints for adaptive beamforming, the inclusion of monopulse, detection and tracking into the adaptive beamforming concept, and the assessment of superresolution methods with respect to their application in a radar system. The problems and achieved results are illustrated by examples from previous publications.

Journal ArticleDOI
TL;DR: In this paper, a three-dimensional microwave holographic imaging method based on the forward-scattered waves only is proposed, where one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on opposite sides of the inspected domain.
Abstract: We propose a three-dimensional microwave holographic imaging method based on the forward-scattered waves only. In the proposed method, one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on opposite sides of the inspected domain. The ability to achieve three-dimensional imaging without back-scattered waves enables the imaging of high-loss objects, for example, tissues, where the back-scattered waves may not be available due to low signal-to-noise ratio or nonreciprocal measurement setup. The simulation and experimental results demonstrate the satisfactory performance of the proposed method in providing three-dimensional images. Resolution limits are derived and confirmed with simulation examples.

Journal ArticleDOI
TL;DR: The proposed channel model is based on the tapped-delay line (TDL) structure and considers the correlation between taps both in amplitude and phase and the relationship between the correlation coefficients of complex Gaussian, Weibull, and Uniform random variables (RVs).
Abstract: This paper proposes a non-wide-sense-stationary-uncorrelated scattering (WSSUS) channel model for vehicle-to-vehicle (V2V) communication systems. The proposed channel model is based on the tapped-delay line (TDL) structure and considers the correlation between taps both in amplitude and phase. Using the relationship between the correlation coefficients of complex Gaussian, Weibull, and Uniform random variables (RVs), the amplitude and the phase of taps with different delays are modeled as correlated RVs to reflect the non-WSSUS properties of V2V channels. The effectiveness of the proposed channel model and simulation method is validated by the measurements in different scenarios.

Journal ArticleDOI
TL;DR: In this paper, the authors evaluate some general criteria for designing and setting up corner reflectors, including shape, size, material, location, and others, and an ideal prototype known as the rectangular trihedral with special designs is brought up in Hong Kong to demonstrate the ability of the proposed prototype.
Abstract: PSInSAR technology has been proved to be a powerful tool for monitoring urban ground displacement information to a millimetric accuracy. When it comes to the validation of PS-derived ground deformation, artificial corner reflector (CR) can be very useful due to its relative stability and high signal-to-noise ratio (SNR). In this paper, we will evaluate some general criteria for designing and setting up corner reflectors, including the shape, size, material, location, and others. An ideal prototype known as the rectangular trihedral with special designs is brought up in this paper, and validation experiments were conducted in Hong Kong to demonstrate the ability of the proposed prototype. The field data agreed with theoretical analysis, bringing up an economical and applicable approach for CR application in urban ground deformation monitoring.

Journal ArticleDOI
TL;DR: In this article, a dual-wideband double-layer magnetoelectric dipole unidirectional antenna with a modified horned reflector for 2G/3G/LTE applications is proposed.
Abstract: A novel dual-wideband double-layer magnetoelectric dipole unidirectional antenna with a modified horned reflector for 2G/3G/LTE applications is proposed. Firstly, a double-layer electric dipole structure is presented to provide a dualwideband, whose folded lower layer mainly serves the lower frequency band while the inclined upper layer works for the upper frequency band. In addition, to reduce the size of the antenna and improve impedance matching, a new feeding structure designed with inverted U-shaped and tapered line is introduced. Finally, a modified horn-shaped reflector, instead of a ground plane, is employed to achieve stable and high gains. The antenna prototype can achieve a bandwidth of 24.4% (790 MHz–1010 MHz) with a stable gain of 7.2 ± 0.6 dBi for the lower band, and a bandwidth of 67.3% (1.38 GHz–2.78 GHz) with a gain of 7.5 ± 0.8 dBi for the upper band covering all the frequency bands for 2G/3G/LTE systems. To the best of our knowledge, it is the first double-layer magnetoelectric dipole antenna proposed. Compared with the existing ME dipole antennas, the proposed antenna, which is completely made of copper, can be easily fabricated at low cost and thus is practicable for 2G/3G/LTE applications.

Journal ArticleDOI
TL;DR: In this paper, the authors studied how spatial diversity impacts on the spectrum (singular values) of the spectrum operator of a bounded rectilinear source with the radiated field observed over multiple bounded rectinear domains parallel to the source.
Abstract: The problem of studying how spatial diversity impacts on the spectrum (singular values) of the radiation operator is addressed. This topic is of great importance because of its connection with the so-called number of degrees of freedom concept which in turn is a key parameter in inverse source problems as well as to the problem of transmitting information by waves from a source domain to an observation domain. The case of a bounded rectilinear source with the radiated field observed over multiple bounded rectilinear domains parallel to the source is considered. Then, the analysis is generalized to two-dimensional extended observation domains. Analytical arguments are developed to estimate the pertinent singular value behavior. This allows highlighting the way observation domain features affect spectrum behavior. Numerical examples are shown to support the analytical results.

Journal ArticleDOI
TL;DR: Low profile cavity backed antennas (CBA) based on substrate integrated waveguide (SIW) technology presented in published papers have been reviewed in this article, where operating mechanisms have been discussed and methods for improving the performance, such as bandwidth enhancement, size reduction, and gain improvement, have been presented.
Abstract: Low profile cavity backed antennas (CBA) based on substrate integrated waveguide (SIW) technology presented in published papers have been reviewed in this paper. Their operating mechanisms have been discussed and methods for improving the performance, such as bandwidth enhancement, size reduction, and gain improvement, have been presented. These novel antennas retain the advantage of conventional metallic cavity backed antenna, including high gain, high front-to-back ratio, and low cross polarization level, and also keep the advantages of planar antenna including low profile, light weight, low fabrication cost, and easy integration with planar circuit.

Journal ArticleDOI
TL;DR: A new modeling method of cabin path loss prediction based on support vector machine (SVM) that makes the prediction much easier and more accurate, which covers performance traditional methods in the channel propagation modeling.
Abstract: A new modeling method of cabin path loss prediction based on support vector machine (SVM) is proposed in this paper. The method is trained with the path loss values of measured points inside the cabin and can be used to predict the path loss values of the unmeasured points. The experimental results demonstrate that our modeling method is more accurate than the curve fitting method. This SVM-based path loss prediction method makes the prediction much easier and more accurate, which covers performance traditional methods in the channel propagation modeling.

Journal ArticleDOI
TL;DR: In this article, an extended version of the Elliott's procedure for the design of a pencil beam waveguide longitudinal slot array has been generalized to encompass the designs of shaped beam planar slot arrays, taking into account in an operative way the feeding part of the array.
Abstract: The Elliott’s procedure for the design of a pencil beam waveguide longitudinal slot array has been generalized to encompass the design of shaped beam planar slot arrays. An extended set of design equations, taking into account in an operative way the feeding part of the array, has been devised. From this set of equations, a general and effective design procedure has been set up, shedding light on the constraints posed by a complex aperture distribution. The results of the proposed synthesis procedure have been validated through comparison with a commercial FEM software.