Showing papers in "International Journal of Microwave and Wireless Technologies in 2016"
TL;DR: The origin of the DM concept and development in recent years are reviewed, including its mathematical model, assessment metrics, synthesis approaches, physical realizations, and finally its potential aspects for future studies are reviewed.
Abstract: Directional modulation (DM) is an emerging technology for securing wireless communications at the physical layer. This promising technology, unlike the conventional key-based cryptographic methods and the key-based physical layer security approaches, locks information signals without any requirements of keys. The locked information can only be fully recovered by the legitimate receiver(s) priory known by DM transmitters. This paper reviews the origin of the DM concept and, particularly, its development in recent years, including its mathematical model, assessment metrics, synthesis approaches, physical realizations, and finally its potential aspects for future studies.
48 citations
TL;DR: In this article, a modified semi-circular monopole ultra-wideband (UWB) antenna with a compact antenna size (4.3 × 3.4 cm2) compared to the typical coplanar waveguide (CPW) circular monopole antenna (5.5 × 4 cm2).
Abstract: This paper introduces a compact modified semi-circular monopole ultra-wideband (UWB) antenna. A compact antenna size (4.3 × 3.4 cm2) compared to the typical coplanar waveguide (CPW) circular monopole antenna (5.5 × 4 cm2) is achieved. The proposed antenna is completely proven for UWB communication performance. The antenna is matched over 8.4 GHz bandwidth (2.2–10.6 GHz), with reflection coefficient lower than −10 dB over the band. Matching bandwidth is verified through simulation and measurements of VSWR. Efficient power radiation over the band is proven through radiation efficiency. Radiation efficiency is not lower than 81% at the upper end of the band. Omnidirectional characteristics are proven through, firstly, measured transfer function magnitude at three different configurations, Face-to-Face, Face-to-Side, and Side-by-Side (all frequencies at different orientations), and, secondly, measured radiation pattern at three selected frequencies that span the bandwidth (all orientations at different frequencies). Moreover, the ability of the antenna to support, as narrow pulses as, 0.25 ns omnidirectionally is proven through detailed study for time response. Antenna transfer function is measured for magnitude and phase. Then, a first-order Raeighly pulse, that fulfils the FCC mask for emission restrictions, is applied at the terminals of a UWB system of the proposed UWB antenna. Finally, the output, barely distorted, normalized, pulse is compared to the input pulse.
43 citations
TL;DR: In this paper, an engineered novel tunable dual-band metamaterial antenna based on stacked split ring resonator (SRR) array is presented for global positioning satellite applications.
Abstract: An engineered novel tunable dual-band metamaterial antenna based on stacked split ring resonator (SRR) array is presented. The μ-negative SRR array present at two sublayers of stacked microstrip patch antenna substrate adds tuning capability to the antenna with marginal trade-off between antenna gain and cross-polarization. If the size of resonator element is considerably smaller than resonance wavelength, ideally lesser than λ/10, the resonator would support the resonating mode of antenna. Compact SRR array embedded in radiator facilitate the antenna tuning to intended allocated spectrum of L5- and S-band frequencies without modifying external dimensions of patch antenna, which in turn helps the satellite payload design. The variations in SRR array dimensions and inter-element spacing are subsequently utilized to maintain the antenna gain and voltage-standing wave ratio. The proposed design of inset fed antenna, matched at 50 Ω, was validated by experimental results and it is suitable for global positioning satellite applications.
41 citations
TL;DR: In this paper, a simple broadband planar monopole microstrip patch antenna with curved slot and partial ground plane is proposed for 2.4/5.8 GHz WLAN bands, 2.5/3.5 GHz WiMAX bands, and other wireless communication services.
Abstract: This paper presents a simple broadband planar monopole microstrip patch antenna with curved slot and partial ground plane. The proposed antenna is designed and fabricated on commercially available FR4 material with er = 4.3 and 0.025 loss tangent. Bandwidth enhancement has been achieved by introducing a curved slot in the patch and optimizing the gap between the patch and the partial ground plane and the gap between the curved slot and the edge of the patch. Simulated peak gain of the proposed antenna is 4.8 dB. The impedance bandwidth (defined by 10 dB return loss) of the proposed antenna is 109% (2–6.8 GHz), which shows bandwidth enhancement of 26% as compared with simple monopole antenna. The antenna is useful for 2.4/5.2/5.8-GHz WLAN bands, 2.5/3.5/5.5-GHz WiMAX bands, and other wireless communication services. Measured results show good agreement with the simulated results. The proposed antenna details are described and measured/simulated results are elaborated.
37 citations
TL;DR: In this paper, the authors proposed a new microstrip-fed printed slot antenna for use in dual-band wireless applications, which is in the form of Cantor square fractal geometry of the second iteration.
Abstract: Fractal geometries are attractive for antenna designers seeking antennas with compact size and multiband resonant behavior. This paper presents the design of a new microstrip-fed printed slot antenna for use in dual-band wireless applications. The slot structure of the proposed antenna is in the form of Cantor square fractal geometry of the second iteration. The slot structure has been etched on the ground plane of a substrate with relative permittivity of 4.4 and 1.6 mm in thickness. A parametric study is conducted to explore the effects of some geometrical parameters on the antenna performance. Results show that the antenna possesses a dual-band behavior with a wide range of resonant frequency ratio. In addition to the ease of fabrication and simple design procedure, the antenna offers desirable radiation characteristics. A prototype of the proposed antenna has been simulated, fabricated, and measured. The measured 10 dB return loss bandwidths for the lower and the upper resonant bands are 42% (2.35–3.61 GHz) and 20% (5.15–6.25 GHz), respectively. This makes the proposed antenna suitable to cover a number of operating bands of wireless systems (2.4 GHz-Bluetooth, 2.4 GHz ISM, 2.4/5.8 GHz-WLAN, 3.5 GHz-WiMAX, and 5.8 GHz-ITS).
33 citations
TL;DR: In this paper, a simple and compact microstrip antenna of circular geometry with circular cut defected patch surface has been proposed for significant suppression of cross-polarized (XP) radiation compared with maximum co polarized gain.
Abstract: A simple and compact microstrip antenna of circular geometry with circular cut defected patch surface has been proposed for significant suppression of cross-polarized (XP) radiation compared with maximum co-polarized gain without affecting the co-polarized radiation pattern at its dominant mode. This will enhance the polarization purity in the radiation performance of the proposed antenna. About 27–28 dB isolation between co-polarized and XP radiations is achieved with the proposed structure. The present structure is simple and easy to develop commercially. The investigation of the new structure is carried out with a view to eliminate orthogonal resonance, which is generally attributed for high XP radiation from the microstrip patch antenna with conventional circular geometry. Comprehensive study on the resonance and radiation characteristics of the new geometry is presented. The present investigation provides an insightful visualization-based understanding of XP suppression with the present structure.
30 citations
TL;DR: In this paper, a new antenna with dimensions of 28 × 28 × 0.8 mm3 and the ability of operating in ultra wideband (UWB) frequency and switching three notched bands was proposed.
Abstract: In this paper, a new antenna has been proposed with dimensions of 28 × 28 × 0.8 mm3 and the ability of operating in ultra-wideband (UWB) frequency and switching three notched bands. In the structure, to achieve the removal of characteristic of three frequency bands, a rectangular patch with an H-shaped slot on its surface and two C-shaped arms on its sides have been used. In addition, the designed antennas have the ability of operating in five different modes. To achieve the performance of reconfiguring, three pin diodes are used on the slots of rectangular patch and those two C-shaped arms. Also, with the defect ground structure and creating two rectangular slots and two L-shaped slots on the ground plane we make the excite of additional resonances and thus increase antenna bandwidth. Simulation and measurement results show that the designed antenna is able to cover the range of frequencies 3–12 GHz and a controllable frequency band rejection in the three frequency bands 3.2–3.75 GHz (WiMAX), 5.05–5.9 GHz (WLAN), and 8–8.45 GHz (ITU). The proposed antenna decreases the interference of the mentioned wireless systems with the UWB frequency.
29 citations
TL;DR: In this paper a wideband multi-input multi-output (MIMO) antenna system for WiFi-LTE wireless access point (WAP) application is proposed and a novel structure of parasitic element is introduced to improve the isolation between the antennas.
Abstract: In this paper a wideband multi-input multi-output (MIMO) antenna system for WiFi-LTE wireless access point (WAP) application is proposed. The MIMO antenna system consists of two common element microstrip-fed monopole antennas with dual polarization. Physically closed integration of MIMO antenna elements requires a special technique to increase the isolation between the antennas. A novel structure of parasitic element is introduced to improve the isolation between the antennas. The proposed MIMO antenna system is simulated and optimized using CST Microwave Studio. The designed antenna system is fabricated and measured to verify the simulation results. Reflection coefficient of less than −10 dB and isolation more than 15 dB are achieved in the operating frequency range of 2.3–2.9 GHz which covers WiFi 2.4 GHz and LTE 2.6 GHz bands. The proposed system also provides dual polarization with 10 dB polarization diversity gain and envelope correlation coefficient less than 0.15. Each individual antenna has a gain of 5.1 dB and 68% efficiency.
28 citations
TL;DR: In this article, asymmetric slits loaded irregular shaped microstrip patch antenna with three different ground structures is proposed and three antennas show triple band characteristics: 1.95 GHz, 2.4 GHz, and 4.85 GHz.
Abstract: Asymmetric slits loaded irregular shaped microstrip patch antenna with three different ground structures is proposed. All three antennas show triple band characteristics. First antenna with regular ground plane resonates at 1.95, 2.4, and 4.90 GHz with good radiation characteristics and shows right-hand circular polarization at 1.95 GHz. 18.75% of compactness is achieved with triple band characteristics. Further, same patch is used with different defected ground structures. Second antenna resonates at 1.85, 2.4, and 4.85 GHz with suppressed cross-polarization level and antenna shows right-hand circular polarization at 1.85 and 4.85 GHz. Compactness is further improved to the value of 22.91%. The third antenna resonates at 1.95, 2.4, and 4.85 GHz with better gain and radiation characteristics and antenna shows right-hand circular polarization at 1.95 and 2.4 GHz. The small frequency ratio f2/f1 is achieved and the value of f2/f1 is 1.29 and 1.23 for second and third configuration, respectively. Proposed structures show right-hand circularly polarized with suppressed left-hand circularly polarized radiations and suitable for fixed mobile wireless communication applications. All structures are analyzed using Ansoft HFSS v.14 based on finite element method and measured results satisfy the simulated results.
22 citations
TL;DR: In this paper, a broadband printed monopole antenna with U-shaped slit in the partial ground plane and rectangular parasitic patches adjacent to the microstrip line for multiple applications is presented.
Abstract: This paper presents a compact broadband printed monopole antenna with U-shaped slit in the partial ground plane and rectangular parasitic patches adjacent to the microstrip line for multiple applications. The optimal dimensions of the proposed antenna are 35 × 25 × 1.5 mm3 and is fabricated on commercially available low-cost FR4 substrate with er = 4.3 and 0.025 loss tangent. Due to introduction of rectangular parasitic patches and U-shaped slit large bandwidth has been achieved. The impedance bandwidth (return loss, magnitude of S11 < 10 dB) of the proposed antenna is 139% (2.9–16.3 GHz). The proposed antenna covers ultra wide band applications, 5.2/5.8 GHz WLAN bands, 3.5/5.5 GHz WiMAX bands, X band (8–12 GHz), satellite communication, and other wireless communication services. The study shows that there is good agreement in simulated and measured results. Nearly stable radiation patterns have been obtained throughout the operating band. Antenna results and details are discussed and elaborated.
21 citations
TL;DR: In this article, a novel compact multiple-input-multiple-output (MIMO) antenna system operating from 5 to 7.3 GHz is proposed for wireless applications, which consists of two similar antennas with microstrip feeding and radiating patches developed on a reduced ground plane.
Abstract: A novel compact multiple-input–multiple-output (MIMO) antenna system operating from 5 to 7.3 GHz is proposed for wireless applications. It comprises of two similar antennas with microstrip feeding and radiating patches developed on a reduced ground plane. The developed antenna system resonates at a dual-band of 5.4 and 6.8 GHz frequencies, giving an impedance bandwidth of 38% (based on S11 < −10 dB). The unique structure of the proposed MIMO system gives a reduced mutual coupling of −27 dB at 5.4 GHz resonant frequency and −19 dB at 6.8 GHz resonant frequency and in the entire operating band the coupling is maintained well below −16 dB. The envelope correlation coefficient of the proposed MIMO system is calculated and is found to be less than 0.05 in the operating band. The measured and simulation results are found in good agreement.
TL;DR: In this article, the authors presented three iterations of a coplanar waveguide-fed H-tree fractal antenna for IEEE 802.11 a/h/j/n/ac/y networks.
Abstract: This paper presents three iterations of a coplanar waveguide-fed H-tree fractal antenna. Increasing the number of iterations allows us obtaining a multi-band and broad-band behavior. The proposed antennas are a good solution for wireless local area networks IEEE802.11 a/h/j/n/ac/y, worldwide interoperability for microwave access system IEEE802.16, radio frequency identification, C-band, high performance radio LAN, and ultra wideband applications. The simulations were performed in FEKO 6.3. The measurements were performed by the network analyzer HP 8719C.
TL;DR: In this article, a planar monopole antenna with impedance bandwidth from 2.83 to 11.56 GHz and dual band-notched characteristics is presented, which consists of a small rectangular ground plane, a bat-shaped radiating patch, and a 50-Ω microstrip line.
Abstract: In this paper, an ultra-wideband (UWB) planar monopole antenna with impedance bandwidth from 2.83 to 11.56 GHz and dual band-notched characteristics is presented. The antenna consists of a small rectangular ground plane, a bat-shaped radiating patch, and a 50-Ω microstrip line. The notched bands are realized by introducing two different types of structures. The half-wavelength spiral-slots are etched on the radiating patch to obtain a notched band in 5.15 5.925 GHz for WLAN, HIPERLAN, and DSRC systems. Based on the single band-notched UWB antenna, the second notched band is realized by etching a folded stepped impedance resonator as defected ground structure on the ground plane for WiMAX and C-band communication systems. The notched frequencies can be adjusted by altering the length of resonant cells. Surface current distributions and equivalent circuit are used to illustrate the notched mechanism. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is suitable and a good candidate for UWB applications.
TL;DR: In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) frequency from 3 to 10.7 GHz with two switchable notch bands of 3.3-3.7 and 3.7-4.2 GHz, is presented for cognitive radio (CR) and multiband orthogonal frequency division multiplexing (MB-OFDM) applications.
Abstract: In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) frequency from 3 to 10.7 GHz with two switchable notch bands of 3.3–3.7 and 3.7–4.2 GHz, is presented for cognitive radio (CR) and multiband orthogonal frequency-division multiplexing (MB-OFDM) applications. The proposed antenna has a simple structure and compact size of 17 × 24 mm2. The antenna in the UWB characteristics is obtained using a circular radiator patch with an embedded T-slot on the patch and a rectangular parasitic element that is attached to the patch. The reconfigurability is also achieved by two L-shaped parasitic elements placed in the left and right of the patch that two ideal switches is inserted over the these elements and the circular patch. The function of the antenna can be changed by tuning status of the switches that make the notch bands in application frequencies. The measurement and simulation results show that the antenna has good characteristics for CR application and MB-OFDM, where the UWB antenna is required for spectrum sensing and the switchable band rejection antenna is used for reconfigurable operation.
TL;DR: In this article, a tri-band bandpass filter using two multimode stepped-impedance resonators (SIRs) with a 0° feed structure is presented. And the mode-splitting technique is used by combining two SIRs with electrical coupling.
Abstract: This paper presents a compact microstrip tri-band bandpass filter (BPF) using two multimode stepped-impedance resonators (SIRs) with a 0° feed structure. The fundamental odd-mode and even-mode resonant frequencies and the third resonant frequency are utilized to determine the center frequencies of the tri-band filter. The mode-splitting technique is used by combining two SIRs with electrical coupling. Therefore, two modes generate one passband and the bandwidths can be controlled by the electrical coupling strength. The 0° feed network is applied to create one pair of transmission zeros at each side of all the triple passbands, resulting in high selectivity. Finally, a tri-band BPF with the central frequencies of 1.8, 2.4, and 5.8 GHz, and respective fractional bandwidths of 8.9, 12.5, and 5.3% are designed and fabricated. The simulated and measured results show a good agreement.
TL;DR: In this paper, a new class of quasi-elliptic pass-band filters based on mushroom-shaped metallic resonators is presented, which exploit non-resonating modes to obtain coupling between nonadjacent nodes in the case of in-line geometry.
Abstract: This paper presents a new class of quasi-elliptic pass-band filters in substrate-integrated waveguide technology, which exhibits compact size and modular geometry. These filters are based on mushroom-shaped metallic resonators, and they can be easily implemented using a standard dual-layer printed circuit board manufacturing process. The presented filters exploit non-resonating modes to obtain coupling between non-adjacent nodes in the case of in-line geometry. The resulting structure is very compact and capable of transmission zeros. In this work, the singlet configuration is preliminarily investigated, and a parametric study is performed. The design of three-pole, four-pole, and higher-order filters is illustrated with examples and thoroughly discussed. A four-pole filter operating at the frequency of 4 GHz has been manufactured and experimentally verified, to validate the proposed technique.
TL;DR: In this article, a dual-band, dual-polarized microstrip antenna element for array applications is presented, which is designed to operate simultaneously at around 30 and 20 GHz, the up-and downlink frequencies of modern Ka-band satellite communication systems.
Abstract: In this contribution a dual-band, dual-polarized microstrip antenna element for array applications is presented. The patch antenna is designed to operate simultaneously at around 30 and 20 GHz, the up- and downlink frequencies of modern Ka-band satellite communication systems. The antenna is smaller than half the freespace wavelength at 30 GHz to enable its utilization as array element of dual-band ground terminals. Integrating transmitter and receiver circuits allows, in turn, for a very compact active terminal solution. To minimize production cost, the design is carried out in standard multilayer printed circuit board technology. The antenna features two distinct polarization ports suitable for either dual linear or dual circular polarization if both ports are excited in quadrature. The single antenna design process is described in detail and simulation and measurement results are presented. Finally, different arrays based on this patch antenna are evaluated by simulation and measurements.
TL;DR: In this paper, the authors describe a stepped impedance resonator (SIR) built from two coaxial structures fitted inside one another, where the ground conductor of the first one is the central core of the next, or vice-versa.
Abstract: This paper describes a concept of stepped impedance resonators (SIR) built from two coaxial structures fitted inside one another. The resonator is built out of a succession of two coaxial sections in cascade, where the ground conductor of the first one is the central core of the next, or vice-versa. An advantageous property of SIR is that they allow a substantial reduction in size, while keeping away the first harmonic and without strongly degrading the quality factor. After describing the theoretical behavior of the resonator, we will then present the specific properties of this approach in second order filter, conceived, and realized in the UHF band. With this example, we will also address flexibility and tunability aspects, which are the other potentially useful properties of the structure. Measurements and simulations are presented and discussed. The architecture resembles a set of two Russian dolls that fit inside one another.
TL;DR: In this article, a dual wideband microstrip antenna (MSA) has been presented for wireless local area networks (WLAN), worldwide interoperability for microwave access (Wi MaX) and U-NII band applications.
Abstract: In this paper, a dual wideband microstrip antenna (MSA) has been presented for wireless local area networks (WLAN), worldwide interoperability for microwave access (Wi MaX) and U-NII band applications. The antenna is designed and simulated using CSTMWS V'10. The main goal of this paper is to get multi-frequency behavior by cutting resonant slots into the patch of the antenna and a wideband antenna behavior using an aperture coupled feeding method. The designed antenna has a semi-spiral G-shaped compact structure and an electromagnetically coupled feeding mechanism (aperture-coupled feeding). It is fabricated on an FR4 substrate with a dielectric constant of 4.4 and a dielectric loss tangent of 0.009. The testing of prototype antenna (to measure S11) is done using a vector network analyzer. The measured results are 80% matching to the simulated ones. The parametric study, simulation results, measured results, and applications of the MSA for WLAN, WiMAX, and the FCC unlicensed 5.2 GHz National Information Infrastructure (U-NII) bands are presented in the paper. The antenna shows a simulated gain of about 4.5 dB at the three wireless application bands.
TL;DR: In this article, a fully integrated ultra-low-power ultra wide band (UWB) pulse generator was designed and optimized for low rate and localization applications, which achieved high energy sub-nanosecond pulses.
Abstract: This paper presents the design of a fully integrated ultra-low-power Ultra Wide Band (UWB) pulse generator. The circuit is designed and optimized for low rate and localization applications. This UWB transmitter is based on the impulse response filter method in order to achieve high energy sub-nanosecond pulses. The circuit has been integrated in a ST-Microelectronics CMOS 0.13 mu m technology with a supply voltage of 1.2 V on a die area of 0.56 mm(2). A power manager is used to reduce the power leakages to 3.91 mu W which gives a power consumption of 3.98 Mw at 10 kb/s. The measured dynamic energy consumed per pulse is 68 pJ and the measured energy of the emitted pulse is 2.15 pJ.
TL;DR: A methodology based on impedance matching network adaptation and maximum power transfer is proposed to design the wideband RF harvester and it is shown that with three RF sources in the chosen bands, the RF-to-DC conversion efficiency is 15% better compared to that measured with a single RF source.
Abstract: In this paper, a 1.8–2.6 GHz wideband rectenna is designed for radio frequency (RF) energy harvesting in the context of wireless sensor nodes (WSN). To assess the feasibility of ambient RF energy harvesting, the power density from RF base stations is analyzed through statistical measurements. Power density measurements are also performed close to Wi-Fi routers. Using these results, a methodology based on impedance matching network adaptation and maximum power transfer is proposed to design the wideband RF harvester. Using this method, three RF bands, i.e. GSM1800, UMTS and WLAN, are covered. The theoretical analysis is confirmed by simulations and measurements. From measurements results, the prototype RF-to-DC conversion efficiency is 15% at −20 dBm from 1.8 to 2.6 GHz. It is shown that with three RF sources in the chosen bands, each emitting at 10 dBm, the RF-to-DC conversion efficiency is 15% better compared to that measured with a single RF source. Finally, 7 µW is harvested at 50 m from a GSM1800 and UMTS base station. This value confirms the RF harvester workability to supply small sensors.
TL;DR: In this paper, a novel design of compact wideband multiple-input multiple-output (MIMO) antenna operating over a frequency range of 1.8-4.0 GHz at 10 dB is presented for mobile terminals.
Abstract: In this paper, a novel design of compact wideband multiple-input multiple-output (MIMO) antenna operating over a frequency range of 1.8–4.0 GHz at 10 dB is presented for mobile terminals. The MIMO antenna design consists of two symmetrical and orthogonal radiating elements with a small size of 15.5 × 16.5 mm2 printed on the corners of a mobile circuit board. The radiating element is composed of four meandered monopole branches with a strip-line fed by a probe. By triangularly trimming the corners of the common ground plane beneath the radiating elements, not only the mutual coupling is reduced, but also impedance bandwidth is increased. Although, the antenna in this form has sufficient correlation level between the radiating elements for MIMO operation, a novel design of plus-shaped parasitic element is inserted to the ground plane between those radiating elements in order to further enhance the isolation. The performance of the MIMO antenna is investigated in terms of s-parameters, radiation pattern, gain, envelope correlation coefficient (ECC), and total active reflection coefficient (TARC), and is verified through the measurements. The results demonstrate that the proposed MIMO antenna has good characteristics of wideband, isolation, gain, radiation pattern, and is compatible with LTE, WiMAX, and WLAN, besides it is small, compact, and embeddable in mobile terminals.
TL;DR: To make a faster CAD module for the stacked-antenna design problem, the simulator has been replaced by a trained artificial neural network and embedded in a particle swarm optimization algorithm (PSOA).
Abstract: Since a conventional microstrip patch antenna is inherently a narrowband radiator, stacked-patch antennas are commonly used either to enhance the bandwidth or to achieve multi-band characteristics However, the stacked patch structure has a number of geometrical variables which need to be optimized to achieve the desired characteristics The conventional design procedure involves repeated costly and time-consuming simulations on an electromagnetic simulator to optimize the various geometrical parameters to arrive at the desired radiation characteristics In this paper, the task of stacked patch antenna design has been approached as an optimization problem In order to make a faster CAD module for the stacked-antenna design problem, the simulator has been replaced by a trained artificial neural network (ANN) and embedded in a particle swarm optimization algorithm (PSOA) The ANN is helpful in constructing the “function mapping black-box”, which can relate the frequencies and associated bandwidths of the antenna with its dimensional parameters The role of the PSOA is to decide the geometrical parameters of the antenna, in response to the designer-specified frequencies and bandwidths In order to validate the authenticity of the proposed method, a number of antennas have been designed, fabricated, and tested in the laboratory Simulated and measured results have been compared which establish the accuracy of the proposed technique
TL;DR: In this paper, a single-fed circularly polarized microstrip antenna is proposed where the antenna structure exhibits truncated corners in the radiating square patch and is loaded with a circular slot and is resonating at 2.25 GHz with circular polarization.
Abstract: A single-fed circularly polarized microstrip antenna is proposed where the antenna structure exhibits truncated corners in the radiating square patch. The truncated corners square patch structure is loaded with a circular slot and is resonating at 2.25 GHz with circular polarization. Furthermore, the proposed antenna is stacked using an upper circular patch thus achieving a dual-band circularly polarized pattern. The dual-band antenna resonates at 2.25 GHz in the first band and with impedance bandwidth ranging from 4.4 to 5.5 GHz in the second band. The size of the proposed stacked structure is compact compared with the conventional circularly polarized stacked antenna designs. Proposed structures are fabricated and fed using Subminiature version A (SMA) connector. The measured results are in good agreement with the simulated. The antenna shows stable radiation characteristics for the entire band of operation.
TL;DR: In this article, a mushroom-type electromagnetic band gap (EBG) structure consisting of fractal periodic elements was used for enhancing the gain of microstrip patch antennas, and the performance of rectangular patch antenna has been examined on proposed fractal EBG substrates.
Abstract: This is the first report on novel mushroom-type electromagnetic band gap (EBG) structures, consisting of fractal periodic elements, used for enhancing the gain of microstrip patch antennas. Using CST Microwave studio the performance of rectangular patch antenna has been examined on proposed fractal EBG substrates. It is found that fractal EBGs are more effective in suppressing surface wave thus resulting in higher gain. The gain of rectangular patch has been improved from 6.88 to 10.67 dBi. The proposed fractal EBG will open new avenues for the design and development of variety of high-frequency components and devices with enhanced performance.
TL;DR: In this article, compressive sensing (CS) was used to obtain efficient reconstruction of through-the-wall imaging radar signals with high resolution, which is an everexpanding area in which processing time, scanning time, vertical, and horizontal resolutions have been tried to improve.
Abstract: Through-the-Wall Imaging is an ever-expanding area in which processing time, scanning time, vertical, and horizontal resolutions have been tried to improve. In this study, several methods are investigated to obtain efficient reconstruction of through-the-wall imaging radar signals with high resolution. Microwave radar signals, which are produced in YTU Microwave Laboratory, are processed by compressive sensing (CS). B and C scanned reflection data samples collected between 1 and 7 GHz frequency band are taken randomly at 1/4, 1/2 of whole amount and reconstructed by CS method. Considering the signal structure, 10 and 20 compressible Fourier coefficients are taken through CS to analyze the difference between them. In addition, we applied synthetic aperture radar (SAR) processing, also combined with SAR-Multiple Signal Classification over raw data. Experimental performance results are given and shown in the figures with high quality.
TL;DR: In this article, a new circularly polarized planar array antenna using linearly polarized microstrip patches is designed and optimized for X-band wireless communication applications, where four square patch elements with feed network are used to design the circularly polarizing array antenna.
Abstract: A new circularly polarized planar array antenna using linearly polarized microstrip patches is designed and optimized for X-band wireless communication applications. Four square patch elements with feed network are used to design the circularly polarized array antenna. The feed network consists of microstrip lines on the obverse side of the dielectric substrate and slot line on the reverse side of the substrate. Both-sided MIC technology is successfully employed to apply its inherent advantages in the design process of the array structure. The unequal feed line is used to create 90° phase difference between the linearly polarized patches. Therefore, the circular polarization is realized by the combination of linearly polarized patches and unequal feed line. Characteristics of the proposed array are investigated by using two electromagnetic (EM) simulators: advanced design system and EMPro. The −10 dB impedance bandwidth of the antenna is around 5%. The 3 dB axial ratio bandwidth of 1.48% is obtained. The design of the proposed antenna along with parametric study is presented and discussed.
TL;DR: In this article, a multi-mode resonator is presented, which is formed by cascading several open-circuited transmission line sections with a coupled-line section, and a microstrip ultra-wide bandwidth (UWB) bandpass filter is designed, fabricated, and measured.
Abstract: In this paper, a novel multi-mode resonator is presented, which is formed by cascading several open-circuited transmission line sections with a coupled-line section. Owing to its symmetry, even- and odd-mode analysis methods are applied to analyze its resonance characteristic. Based on this resonator, a microstrip ultra-wide bandwidth (UWB) bandpass filter is designed, fabricated, and measured. The simulated and measured results show that its bandwidth can cover the desired UWB. Return loss in passband is better than −14 dB. This filter is featured by good selectivity and wide stopband. Stopband suppression as low as −40 dB can be achieved within frequency range from 12 to 16 GHz.
TL;DR: In this paper, a triple-band 1 × 2 and 1 × 4 microstrip patch antenna array for next-generation wireless and satellite-based applications is presented, where simple design procedures and optimization techniques are discussed to achieve better antenna performance.
Abstract: In this paper, a triple-band 1 × 2 and 1 × 4 microstrip patch antenna array for next-generation wireless and satellite-based applications are presented. The targeted frequency bands are 3.6, 5.2 and 6.7 GHz, respectively. Simple design procedures and optimization techniques are discussed to achieve better antenna performance. The antenna is designed and simulated using Agilent ADS Momentum using FR4 substrate (er = 4.2 and h = 1.66 mm). The main patch of the antenna is designed for 3.6 GHz operation. A hybrid feed technique is used for antenna arrays with quarter-wave transformer-based network to match the impedance from the feed-point to the antenna to 50 Ω. The antenna is optimized to resonate at triple-bands by using two symmetrical slits. The single-element triple-band antenna is fabricated and characterized, and a comparison between the simulated and measured antenna is presented. The achieved simulated impedance bandwidths/gains for the 1 × 2 array are 1.67%/7.75, 1.06%/7.7, and 1.65%/9.4 dBi and for 1 × 4 array are 1.67%/10.2, 1.45%/8.2, and 1.05%/10 dBi for 3.6, 5.2, and 6.7 GHz bands, respectively, which are very practical. These antenna arrays can also be used for advanced antenna beam-steering systems.
TL;DR: In this paper, a simple synthesis technique to obtain the geometrical parameters of the modified circular ring for angular and polarizations (perpendicular and parallel) stable frequency selective surface (FSS) has been discussed.
Abstract: In this paper, a simple synthesis technique to obtain the geometrical parameters of the modified circular ring for angular and polarizations (perpendicular and parallel) stable frequency selective surface (FSS) has been discussed. The geometrical parameters of the modified circular ring FSS structure have been achieved using the proposed synthesis technique, which is based on the equivalent circuit (EC) approach. In addition to this, the numerical analysis is also discussed to determine the values of EC parameters, which depends on the basic system level characteristics such as frequency of operation and reflection/transmission coefficients. The analytical results are supported using the full-wave three-dimensional electromagnetic (EM) simulators such as CST Microwave Studio and Ansoft HFSS. The sensitivity of the structure to the perpendicular and parallel polarized EM wave up to 50° angle-of-incidences (AOIs) has been discussed. The stability over different AOI is attributed to the appropriate thickness of the structure with its small unit-cell dimensions. We have also fabricated and experimentally tested the proposed FSS structure.