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Showing papers in "International Journal of Microwave and Wireless Technologies in 2017"


Journal ArticleDOI
TL;DR: An extensive thorough investigation of diversity and mutual coupling (correlation) reduction techniques in compact MIMO antennas is carried out.
Abstract: Multiple input multiple output (MIMO) antenna is at core of the presently available wireless technologies. The design of MIMO antennas over a limited space requires various approaches of mutual coupling reduction, otherwise gain, efficiency, diversity gain, and radiation patterns will be severely affected. Various techniques have been reported in literature to control this degrading factor and to improve the performance of the MIMO antennas. In this review paper, we have carried out an extensive thorough investigation of diversity and mutual coupling (correlation) reduction techniques in compact MIMO antennas.

110 citations


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

68 citations


Journal ArticleDOI
TL;DR: In this article, different configurations of leaky-wave antennas (LWAs) based on graphene metasurfaces are studied, and exact formulas for evaluating the ohmic losses related to surface plasmon polariton (SPP) propagation along a suspended graphene sheet are given.
Abstract: Different configurations of leaky-wave antennas (LWAs) based on graphene metasurfaces are studied. The electronic properties of a graphene metasurface in the low THz range are investigated in details in order to discuss the reconfigurability features of the presented structures. Simple exact formulas for evaluating the ohmic losses related to the surface plasmon polariton (SPP) propagation along a suspended graphene sheet, and the relevant figures of merit of SPP propagating over a generic metasurface are given. Such formulas allow us to explain the low efficiency of reconfigurable antennas based on SPPs along graphene metasurfaces. Then, the radiative performance and relevant losses of graphene Fabry–Perot cavity antennas (FPCAs) based on non-plasmonic leaky waves (LWs) are investigated and compared with previous solutions based on SPPs. In particular, a single-layer structure, i.e. a grounded dielectric slab covered with a graphene metasurface, and a multilayered structure, i.e. a substrate–superstrate antenna in which the graphene metasurface is embedded at a suitable position within the substrate, are considered in detail. The results show that the proposed LW solutions in graphene FPCAs allow for considerably reducing the ohmic losses, thus significantly improving the efficiency of the proposed radiators.

39 citations


Journal ArticleDOI
TL;DR: The proposed antenna provides feasibility to WLAN and WiMAX communication standards in a single device with good radiation pattern quality and a prototype of the proposed antenna fabricated and measured to validate the design, shows a good agreement between simulated and measured results.
Abstract: To incorporate two different communication standards in a single device, a compact triple-band antenna is proposed in this paper. The proposed antenna is formed by etching an inverted L-shaped slot on the patch with defected ground structure. The antenna is targeted to excite three separate bands first from 2.39–2.51, second from 3.15–3.91, and third from 4.91–6.08 GHz that covers entire Wireless Local Area Network (WLAN) (2.4/5.2/5.8 GHz) and Worldwide Interoperability for Microwave Access (WiMAX) (2.5/3.5/5.5) bands. Thus, the proposed antenna provides feasibility to integrate WLAN and WiMAX communication standards in a single device with good radiation pattern quality. Furthermore, a prototype of the proposed antenna fabricated and measured to validate the design, shows a good agreement between simulated and measured results. The simulation and measurement results show that the designed antenna is capable of operating over the 2.39–2.51 GHz, 3.15–3.91 GHz, and 4.91–6.08 GHz frequency bands while rejecting frequency ranges between these three bands. The proposed antenna offers a compact size of 20 × 30 mm2 as compared with earlier reported papers.

37 citations


Journal ArticleDOI
TL;DR: A frequency reconfigurable microstrip slot antenna for ultra-wideband applications with switchable band-notch functions is designed and manufactured, providing band rejection characteristics at WiMAX and WLAN systems.
Abstract: In this paper, a frequency reconfigurable microstrip slot antenna for ultra-wideband applications with switchable band-notch functions is designed and manufactured. To generate a wide usable fractional bandwidth of 3 to over 13.6 GHz, square patch transforms to a fork-shaped patch, also two triangular-shaped strips have been added at above sections of rectangular slot on the ground plane. Band rejections are obtained by adding two inverted L-shaped strips in the fork-shaped patch and one L-shaped defected ground structure. Moreover, by implementation of two PIN diodes within the antenna structure, four switchable frequency responses are achieved. The designed antenna has simple structure and a small size of 20 × 20 × 0.8 mm3 while providing band rejection characteristics at WiMAX (Worldwide Interoperability for Microwave Access) and WLAN (Wireless Local Area Networks) systems.

34 citations


Journal ArticleDOI
TL;DR: In this article, a metasurface (MS) structure is proposed to convert a linearly polarized wave to circularly polarized waves by using a simple configuration in the proposed structure which consists of 16 unit cells arranged in a 4 × 4 layout.
Abstract: By using a metasurface (MS) structure, a linearly polarized wave is converted to circularly polarized waves. Both right- and left-handed circular polarizations (RHCPs and LHCP) are obtained by a simple configuration in the proposed structure which consists of 16 unit cells arranged in a 4 × 4 layout. Each unit cell contains five horizontal and parallel strips embedded in a rectangular frame in which a single diagonal strip is placed from one corner to the opposed one. It is shown that the orientation of the diagonal line determines the handedness of the converted signal to be either LHCP or RHCP. In order to show the working conditions of the MS structure, scattering parameters are found for both co-polarized and cross-polarized responses. Axial ratio, an indicator for polarization conversion, is then obtained by dividing cross-polar response to co-polar response to demonstrate the transformation. The structure works for horizontally and vertically polarized linear waves in a wide band frequency range which is approximately 510 MHz. Since the suggested MS model is composed of a simple geometry for polarization conversion, it can be easily adjusted in any desired frequency bands for a variety of applications from the defence industry to medical, education, or communication areas.

33 citations


Journal ArticleDOI
TL;DR: This paper presents the design, testing, and analysis of a clover structured monopole antenna for super wideband applications, which is suitable for ultra wideband (UWB) outdoor propagation and experimentally validated for frequencies within and greater than UWB.
Abstract: This paper presents the design, testing, and analysis of a clover structured monopole antenna for super wideband applications. The proposed antenna has a wide impedance bandwidth (−10 dB bandwidth) from 1.9 GHz to frequency over 30 GHz. The clover shaped antenna with a compact size of 50 mm × 45 mm is designed and fabricated on an FR4 substrate with a thickness of 1.6 mm. Parametric study has been performed by varying the parameters of the clover to obtain an optimum wide band characteristics. Furthermore, the prototype introduces a method of achieving super wide bandwidth by deploying fusion of elliptical patch geometries (clover shaped) with a semi elliptical ground plane, loaded with a V-cut at the ground. The proposed antenna has a 14 dB bandwidth from 5.9 to 13.1 GHz, which is suitable for ultra wideband (UWB) outdoor propagation. The prototype is experimentally validated for frequencies within and greater than UWB. Transfer function, impulse response, and group delay has been plotted in order to address the time domain characteristics of the proposed antenna with fidelity factor values. The possible applications cover wireless local area network, C-band, Ku-band, K-band operations, Worldwide Interoperability for Microwave Access, and Wireless USB.

32 citations


Journal ArticleDOI
TL;DR: In this paper, a band-notched compact printed monopole super wideband (SWB) antenna has been designed and fabricated, which is composed of a radiating patch with a 50 Ω triangular tapered feed line which is connected through a feed region, and a chamfered ground plane (CGP), that covers the frequency band from 0.9-100 GHz (ratio bandwidth of 111.1:1) with a reflection coefficient |S11| < −10 dB.
Abstract: In this paper, a band-notched compact printed monopole super wideband (SWB) antenna has been designed and fabricated. The SWB antenna composed of a radiating patch with a 50 Ω triangular tapered feed line which is connected through a feed region, and a chamfered ground plane (CGP), that covers the frequency band from 0.9–100 GHz (ratio bandwidth of 111.1:1) with a reflection coefficient |S11| < −10 dB, except in the notched band of 4.7–6 GHz for Wireless local area network IEEE 802.11a and HIPERLAN/2 WLAN band. To realize the band notch characteristics a C-shape parasitic element is employed near the CGP etched with two symmetrical L-slots and placed under the radiating patch. Proposed antenna structure occupies a relatively small space (30 × 40 × 0.787 mm3) and achieved much wider impedance bandwidth as well as higher gain compared with the existing ultra wideband and SWB antennas.

29 citations


Journal ArticleDOI
TL;DR: In this article, a metamaterial-based energy harvesting structure operating at GSM 900 and GSM 1800 frequency bands has been proposed, which is composed of four nested U-shaped elements on the front and back side of the dielectric substrate.
Abstract: Metamaterial-based energy harvesting structures operating at GSM 900 and GSM 1800 frequency bands have been proposed. The basic structure is composed of four nested U-shaped elements on the front and back side of the dielectric substrate, with a 180° relationship between the front and back resonators. As energy harvesting capability is directly related to the quality of absorption, with the aim being perfect absorption, there is an air gap to allow tuning of the resonance frequency, and copper plate follows the air gap to facilitate the perfect absorption of electromagnetic waves, which is verified by means of simulation and experimental tests. A set of simulations and experimental study were further carried out to demonstrate incident and polarization angle dependency, the effects of Schottky diodes, and the optimal orientation of the U-shapes. Spectrum analysis and DC voltage measurements across the HSMS 2860 Schottky diode are also presented to test the energy harvesting capability: the spectrum analyzer shows a 40 dBm difference, while 81.7 mV maximum DC voltage is observed at 900 MHz. The simulation and experimental study results, while displaying several differences, do suggest that the proposed design can be used for running low-energy consumption devices such as sensors and switches.

27 citations


Journal ArticleDOI
TL;DR: In this article, an X-shaped fractal antenna with defected ground structure (DGS) is presented for multiband and wideband applications in the frequency range of 1-7 GHz.
Abstract: In this paper, an X-shaped fractal antenna with defected ground structure (DGS) is presented for multiband and wideband applications. The X shape is used due to its simple design and DGS is utilized to achieve size reduction with multiband and wideband features in the frequency range of 1–7 GHz. The proposed structure is fabricated on FR4 substrate with 1.6 mm thickness. We have proposed two different antennas both are having X-shaped fractal patch with a slotted ground plane to have more impedance bandwidth and better return loss. Various parameters like scale factor, width of ground plane, number of slots with their dimensions and feed line length are optimized to have size reduction and for enhancing the performance of antenna. Reflection coefficient shows the multiband and wideband features of proposed antenna. One of the proposed antennas covers various applications like IEEE802.11y at 3.65 and 4.9 GHz, IEEE 802.11a at 5.4 GHz, 802.11P at 5.9 GHz. Other antenna covers applications like IEEE802.16 at 3.5 GHz; 5 cm band for amateur radio and satellite and future 5 G communication systems over 6 GHz. The antenna designing was done using CST software and simulation results were compared with experimental results (using E5071C network analyzer).

24 citations


Journal ArticleDOI
TL;DR: In this article, a multi-mode resonance concept was proposed for wideband dipole antennas using symmetrically introducing one-pair or two-pair of stubs at the nulls of current distribution of the second odd-order mode, resulting in a wideband radiation with two resonances.
Abstract: Wideband dipole antennas are proposed using the multi-mode resonance concept. By symmetrically introducing one-pair or two-pair of stubs at the nulls of current distribution of the second odd-order mode, two radiation modes are excited in a single, center-fed dipole resonator. Using these stubs, the second odd-order mode gradually moves down to its first counterpart, resulting to achieve a wideband radiation with two resonances. Prototype antennas are then fabricated to experimentally validate the design approach. Compared with a reference dipole with a bandwidth of 17%, the proposed dipole's bandwidth can be effectively increased to 49.7%.

Journal ArticleDOI
TL;DR: In this article, an ultra wideband (UWB) frequency-selective surface (FSS) exhibiting band rejection characteristic is presented, which consists of a single-layer substrate and provides 20 dB attenuation level for a wide bandwidth of 7.53 GHz at the normal incidence.
Abstract: An ultra-wideband (UWB) frequency-selective surface (FSS) exhibiting band rejection characteristic is presented in this paper. The proposed unit cell has the size of 14 × 14 mm2 which is approximately 0.18 × 0.18 λo, where λo corresponds to free space wavelength at the lower cut-off frequency. The proposed UWB FSS consists of a single-layer substrate and provides 20 dB attenuation level for a wide bandwidth of 7.53 GHz at the normal incidence. The proposed FSS is polarization independent and also provides angular-independent operation for the EM wave incidences of 15°, 30° and 45° with 11.5 dB attenuation over a wide range from 4 to 14 GHz.

Journal ArticleDOI
TL;DR: In this paper, a meta-material inspired loaded monopole antenna for multiband operation is proposed, consisting of multi resonators inspired from half mode composite right/left handed cells, which has a simple structure, compact size, and provides multiband functionalities.
Abstract: The design and analysis of meta-material inspired loaded monopole antenna for multiband operation are reported. The proposed antenna consists of multi resonators inspired from half mode composite right/left handed cells, which has a simple structure, compact size, and provides multiband functionalities. As a proof of concept, a triple band antenna covering all possible WiMAX operating bands, has been designed, fabricated, and characterized. The hosting monopole patch itself generates resonance for 3.3–3.8 GHz band, whereas the loaded metamaterial cells add extra resonance frequencies. The loading of two resonator cells introduces two extra resonances for 2.5–2.7 GHz and 5.3–5.9 GHz bands, respectively. The antenna's operating principle and design procedures with the aid of electromagnetic full wave simulation and experimental measurements are presented. The antenna has good omnidirectional patterns at all three bands. The monopole patch size is 13.5 × 6.5 mm2 and the whole antenna size (including the feed line) is 35 × 32 mm2. Compared with conventional single band microstrip patch radiator, the radiator size of this antenna is only 8.5% at 2.5 GHz, 17% at 3.5 GHz, and 37% at 5.5 GHz.

Journal ArticleDOI
TL;DR: In this article, the influence of the radius of a cylindrical supporting structure on radiation properties of a conformal millimeter-wave antenna array was studied, and the results showed that conformal antenna structures allow achieving large angular coverage and may allow beam-steering implementations if switches are used to select between different arrays around a cyl-indrical support structure.
Abstract: In this paper, we study the influence of the radius of a cylindrical supporting structure on radiation properties of a conformal millimeter-wave antenna array. Bent antenna array structures on cylindrical surfaces may have important applications in future mobile devices. Small radii may be needed if the antenna is printed on the edges of mobile devices and in items which human beings are wearing, such as wrist watches, bracelets, and rings. The antenna under study consists of four linear series-fed arrays of four patch elements and is operating at 58.8 GHz with linear polarization. The antenna array is fabricated on polytetrafluoroethylene substrate with thickness of 127 µm due to its good plasticity properties, and low losses. Results for both planar and conformal antenna arrays show rather good agreement between simulation and measurements. The results show that conformal antenna structures allow achieving large angular coverage and may allow beam-steering implementations if switches are used to select between different arrays around a cylindrical supporting structure.

Journal ArticleDOI
TL;DR: In this paper, the main results of the development of whispering gallery mode (WGM) resonators and their unique applications due to their quasi-optical functionality are reviewed and a separate section of the paper is devoted to application aspects of the WGM resonators.
Abstract: We review the main results of the development of whispering gallery mode (WGM) resonators and their unique applications due to their quasi-optical functionality. Several types of advanced WGM resonators are proposed by the authors. The theoretical results are described for the resonators with an analytical solution of the electromagnetic problems. Special emphasis is given to the interaction of moving charged particles and waves of cylindrical resonators. Important aspects are described concerning the developed sapphire resonators, for which an exact solution can only be found by using specially designed computer program products. A separate section of the paper is devoted to application aspects of the WGM resonators. In particular, it describes advanced solutions for overcoming the problems of measuring the small microwave (MW) surface impedance of unconventional superconductors in the form of large-area thin films and small samples under study. In addition, a demonstration of accurate complex permittivity measurements of small volumes of lossy liquids is provided. Special emphasis is given to highly stable MW signal sources, namely Ka-band transistor-based feedback oscillator and solid-state maser WGM oscillators. Recently obtained results are presented of experimental studies of the auto-oscillatory system developed on the basis of the WGM resonator with relativistic electron beam.

Journal ArticleDOI
TL;DR: In this article, a microstrip diplexer composed of two similar resonators is designed to operate at 2.36 and 4 GHz for wireless applications, where the insertion losses (S21 and S31) are decreased significantly at the resonance frequencies.
Abstract: In this paper, a microstrip diplexer composed of two similar resonators is designed. The proposed resonator is consisting of four microstrip cells, which are connected to a coupled lines structure. In order to select a suitable geometric structure, first, all cells are assumed as undefined structures where there is a lack of basic information about their geometry and dimensions. Then, an equivalent LC circuit of the coupled lines is introduced and analyzed to estimate the general structure of the resonator respect to a requested resonance frequency. The proposed diplexer is designed to operate at 2.36 and 4 GHz for wireless applications. The insertion losses (S21 and S31) are decreased significantly at the resonance frequencies, so that they are 0.2 and 0.4 dB at 2.36 and 4 GHz, respectively. The designed diplexer is fabricated and measured and the measurement results are in a good agreement with the simulations.

Journal ArticleDOI
TL;DR: In this article, a vase-shaped monopole antenna is presented for dual band notch (WiMAX IEEE802.11a/h/j/n 5.15-5.35 GHz, 5.47-6.0 GHz and WLAN with VSWR = 6.39 GHz) and the measured gain is relatively stable across the impedance bandwidth except band-notched.
Abstract: In this paper, a vase-shaped monopole antenna is presented for dual band notch (WiMAX IEEE802.16 3.30–3.80 GHz with C-band 3.80–4.20 GHz and WLAN IEEE802.11a/h/j/n 5.15–5.35 GHz, 5.25–5.35 GHz, 5.47–5.725 GHz, 5.725–5.825 GHz) UWB and other wireless services (close range radar: 8–12 GHz in X-band & satellite communication: 12–18 GHz in Ku-band). Measured VSWR of proposed antenna shows a high band-rejection for WiMAX along with C-band with VSWR = 25.33 at 3.77 GHz and WLAN with VSWR = 6.0 at 5.64 GHz is achieved by cutting two C-shaped slots on the radiating patch. Designed antenna covers a wide usable fractional bandwidth 160% (2.58–20.39 GHz). Furthermore, the measured gain of antenna is relatively stable across the impedance bandwidth except band-notched. In addition, antenna offers omni-directional pattern, reasonably small 20 × 20 × 0.787 mm3 and easy to construct structure.

Journal ArticleDOI
TL;DR: In this paper, a power divider based on half mode substrate integrated waveguide (HMSIW) with an arbitrary power dividing ratio is presented, where a resistor is attached between two HMSIW transitions to adjust the power division ratio.
Abstract: Design and realisation of a compact power divider based on half mode substrate integrated waveguide (HMSIW) with an arbitrary power dividing ratio is presented. This design consists of a substrate integrated waveguide (SIW) transition, two bisected HMSIW transitions by a gap, an SIW-to-microstrip transition, and two microstrip feed lines. In addition, a resistor is attached between two HMSIW transitions. To adjust the power division ratio, four parameters are introduced. Furthermore, four graphs are plotted using a three-dimensional electronmagnetic (3D EM) simulator to graphically determine the introduced parameters. In this study, three circuits with power division ratios of 1:1, 1:4, and 1:8 are simulated using the 3D EM simulator and fabricated on a Rogers RO4003C substrate. The results show a good agreement between the simulated and measured results. The measured results display these circuits (1:1, 1:4, and 1:8) have the bandwidths of 70, 36, and 40%, respectively. Moreover, the proposed structures (1:1, 1:4, and 1:8) are compact and their overall sizes are , , and , respectively. These structures have the advantages of the compactness in size, wide bandwidth, high power division ratio (from 1:1 to 1:16), and compatibility with planar circuits.

Journal ArticleDOI
TL;DR: In this article, a combination of electromagnetic band gap (EBG) and split-ring resonator (SRR) loads with fractal formation for miniaturization of microstrip antenna is noticed.
Abstract: In this paper, combination of electromagnetic band gap (EBG) and split-ring resonator (SRR) loads with fractal formation for miniaturization of microstrip antenna is noticed. Here two different shapes of antenna have been studied with two well-known metamaterial structures as parasitic elements. A conventional microstrip antenna, which is surrounded by four EBG unit cells, is chosen as the first antenna. It has an effective resonance at 2.5. The Minkowski fractal method is applied to EBG unit cells in this stage. The Minkowski fractal structure is implemented for accession of effective capacitance in EBG unit cells. The second antenna frequencies are 2.5 and 5.9 GHz. It contains a slot structure with four SRRs, used for making parasitic elements and for achieving multi-band characteristic. The fractal method is used to improve the inductance of SRR structure by increasing the effective length of microstrip line. At this stage, the applied fractal structure has been modified, so that the frequency of wireless application could be achieved. In the last step, by some changes in feed line of the slot antenna, circular polarization (CP) is obtained for the second antenna, which shows that SRR load can be helpful for making the CP.

Journal ArticleDOI
TL;DR: In this paper, a compact microstrip low-pass filter (LPF) with ultra wide stop band and sharp roll off was proposed, where a high impedance transmission line is loaded by compact micro-strip resonant cells.
Abstract: In this paper, a novel compact microstrip low-pass filter (LPF) with ultra wide stop band and sharp roll off, is proposed. In the proposed structure, a high impedance transmission line is loaded by compact microstrip resonant cells, which results in ultra wide stopband. The −3 dB cut-off frequency of filter is 1.5 GHz and the maximum insertion loss is <0.1 dB in the passband. The proposed LPF presents extremely wide stopband from 1.68 to 44 GHz, with more than the −20 dB attenuation level, which suppresses the 2nd to 29th harmonics with high rejection levels. The size of the proposed LPF is only 0.1 λg × 0.19 λg, which shows excellent size reduction. There is a good agreement between the simulated and measured results.

Journal ArticleDOI
TL;DR: In this article, a split-ring resonators (SRR) loaded coplanar waveguide-fed ultra-wide band (UWB) antenna is proposed to achieve wide band-notched characteristics.
Abstract: This paper presents the design of a split-ring resonators (SRR) loaded coplanar waveguide-fed ultra-wide band (UWB) antenna. As using the electromagnetic coupling SRR connected by open-ended microstrip lines, this UWB antenna achieves wide band-notched characteristics. The frequency of the proposed antenna operates from 2.37 to 10.93 GHz with a broad notch band covers from 4.96 to 6.15 GHz (IEEE 802.11.ac), the relative stopped bandwidth of the notch band achieves 20.42%. Besides, theoretical analysis and experimental results are proposed to illustrate and validate this proposed antenna.

Journal ArticleDOI
TL;DR: In this paper, a two-layer frequency-selective surfaces (FSSs) with an FR4 substrate was used to cover the 10-12 GHz frequency band in a secure room.
Abstract: Use of frequency-selective surfaces (FSSs) is proposed to shield rooms against electromagnetic fields in order to achieve secure indoor communications and reduce human exposure to external fields. The secure room is designed using two-layer FSSs with an FR4 substrate to cover 10–12 GHz frequency band. Different elements in each layer and shift in the position of elements are the reasons for more than 3 GHz bandwidths in X band. The performance of the structure is also stable versus the misaligned position of layers. An equivalent circuit model is proposed for the structure and results show −20 dB isolation between inside and outside of the room in the desired frequency band. Bio tissue is located inside the cubic structure with FSS walls and the results of the specific absorption rate are demonstrated and compared in two rooms with FSS cover on concrete walls and a room with concrete walls. The 17 × 17 cm2 two-layer FSS is fabricated for the measurement and the results are presented. The designed FSS can be used in the construction of wave-isolated room for any application.

Journal ArticleDOI
TL;DR: This paper proposes a novel wideband to concurrent tri-band frequency reconfigurable microstrip antenna that operates from 3.58 to –3.82 GHz, which is 4.08 times larger than the bandwidth of a simple microstrip patch antenna.
Abstract: This paper proposes a novel wideband to concurrent tri-band frequency reconfigurable microstrip antenna. The frequency reconfiguration is achieved by using a pair of PIN diodes in the antenna feed line to switch the antenna either in wideband mode or in concurrent tri-band mode. In order to improve the bandwidth and gain of the antenna for wideband operation, the properties of J-K inverter and split ring resonators are exploited. To demonstrate the versatility of this concept a prototype is fabricated and tested here. The tested results in wideband mode shows that the proposed antenna operates from 3.58 to –3.82 GHz, which is 4.08 times larger than the bandwidth of a simple microstrip patch antenna. In the concurrent tri-band mode frequency tuning is done by microstrip open stub at 1.5 GHz, 1.9 GHz, and 3.5 GHz. Gain of the proposed antenna is better than 2.7 dB in wideband mode and 2.7 dB in concurrent tri-band mode.

Journal ArticleDOI
TL;DR: In this article, a compact antenna system with dual-band notched characteristics is proposed for ultra-wideband (UWB) multiple-input multiple-output (MIMO) applications.
Abstract: In this report, a compact antenna system with dual-band-notched characteristics is proposed for ultra-wideband (UWB) multiple-input multiple-output (MIMO) applications. Two antenna elements are placed side by side and fed with matched microstrip lines on a substrate with an area of 35 × 30 mm2. Notched characteristics at WiMAX (3.4–3.6 GHz) and WLAN (5.725–5.825 GHz) have been achieved using complementary split ring resonator (SRR) slots etched in both the antenna elements. Electromagnetic isolation between the two elements close to each other is achieved using a ground T-stub and slots etched in the ground plane. Antenna system has been tested and measured results are close to the desired ones. Measured isolation >20 dB is obtained in most of the UWB bands. The proposed antenna system meets the requirements well for MIMO applications.

Journal ArticleDOI
TL;DR: In this paper, a novel miniaturized (12 × 18 × 1.6 mm 3 ) microstrip fed UWB antenna with tunable notched band characteristics is presented.
Abstract: We report in this paper a novel miniaturized (12 × 18 × 1.6 mm 3 ) microstrip fed UWB antenna with tunable notched band characteristics. The proposed antenna covers the tunable notched band for IEEE 802.11a wireless local area network operating in the frequency band of 5.15–5.825 GHz. The design of proposed antenna includes annular ring radiating patch with two T-shaped strips present inside it. The band notching is obtained by adjusting coupling between T-shaped strips placed inside the annular ring. In order to achieve larger bandwidth the ground plane of the microstrip antenna is modified. The simulated return loss of the proposed antenna has been verified in fabricated antenna experimentally, which has been in good agreement.

Journal ArticleDOI
TL;DR: In this paper, a microstrip transmission line fed fork-shaped planar antenna is proposed for Bluetooth, WLAN, and WiMAX applications, which shows the measured bandwidth of 410 MHz (2.26-2.67) and 3.78 GHz (3.0-6.78GHz) at lower and upper bands, respectively.
Abstract: A microstrip transmission line fed fork-shaped planar antenna is proposed for Bluetooth, WLAN, and WiMAX applications. The antenna made of a microstrip feed line, fork-shape patch on one side and defected ground plane on the other side of dielectric substrate. A fork-shape is formed by two side circular arms and a rectangular central arm. The inverted T-shaped ground plane with a rectangular slot in the center arm is used to increase the bandwidth with better impedance matching of the lower band. The antenna is practically fabricated to validate the design. The antenna resonate dual band to cover an entire the WLAN and WiMAX bands. The antenna shows the measured bandwidth of 410 MHz (2.26–2.67) and 3.78 GHz (3.0–6.78 GHz) at lower and upper bands, respectively.

Journal ArticleDOI
TL;DR: The proposed compact tri-band asymmetric coplanar strip (ACS)-fed meander-line antenna has compact size and simple feeding scheme, which make it suitable to be integrated within the portable device for wireless communications.
Abstract: In this paper, a compact tri-band asymmetric coplanar strip (ACS)-fed meander-line antenna for wireless communications is proposed. Two inverted-L-shaped resonators are added to a simple meandered radiator for standard tri-band operation. Parametric studies indicate that operating frequencies of the proposed antenna are determined by the dimensions of the two inverted-L-shaped resonators. The measured results show that the proposed antenna can achieve three frequency bands; i.e. 1.48–1.63, 2.25–2.48, and 4.22–6.0 GHz. These bands can successfully cover the global positioning system L1, wireless local area network (WLAN), and HIPERLAN/2 operation bands, respectively. The proposed antenna exhibits good radiation patterns with reasonable gain and high radiation efficiency across the operating bands. In addition, the proposed antenna has compact size and simple feeding scheme, which make it suitable to be integrated within the portable device for wireless communications.

Journal ArticleDOI
TL;DR: In this paper, a 2.45 GHz wideband harmonic rejection rectenna for wireless power transfer is proposed, which comprises a microstrip-fed circular ring slot antenna (CRSA) and a series-parallel rectifier (SPR).
Abstract: In this paper, a 2.45-GHz wideband harmonic rejection rectenna for wireless power transfer is proposed. The rectenna comprises a microstrip-fed circular ring slot antenna (CRSA) and a series-parallel rectifier (SPR). A compact micro strip resonant cell is inserted into the CRSA so that the harmonic suppression over a wide bandwidth (3–8 GHz) can be obtained. The radio-frequency (RF)–DC conversion efficiency of the SPR is improved effectively by loading a proper compensating inductance, especially under the low input power levels. Furthermore, the proposed rectenna can easily achieve large-scale rectenna arrays using its simple structure. The adopted rectenna fabricated on a low cost Taconic RF-35 substrate has been measured. By up to 3rd-order harmonic rejection, the efficiency of the rectenna can achieve 70.2% with the optimum load resistance 1 kΩ. Good agreement among the calculated, simulated, and measured rectenna is observed.

Journal ArticleDOI
TL;DR: In this paper, a lamp-shaped UWB microstrip antenna with dual band-notched characteristics is presented, which is suitable to be integrated within the portable UWB devices without EMI interference at WiMAX and WLAN bands.
Abstract: To restrict electromagnetic interference at WiMAX (3.3–3.7 GHz) and wireless local area network (WLAN) (5.15–5.825 GHz) bands operating within ultra wide bandwidth (UWB) band, a novel design of lamp-shaped UWB microstrip antenna with dual band-notched characteristics is presented. The proposed antenna is composed of a lamp-shaped radiating patch with two rectangular ground planes on both the sides of the radiator with the gap of 0.57 mm. To improve impedance mismatch at middle frequencies, two triangular strips one at each of the ground plane are added; whereas a rectangular slot is etched in the radiating patch to remove impedance mismatch at higher frequencies of the UWB band. Furthermore, an L-shaped slot in the radiator and two L-shaped slots in the ground plane are used to restrict electromagnetic interference (EMI) at WiMAX and WLAN bands, respectively, without affecting the electrical performance of the UWB antenna. Effects of the key parameters on the frequency range of the notched bands are also investigated. The proposed design shows a measured impedance bandwidth of 12.5 GHz (2.7–14.4 GHz), with the two band-notched bands of 3.0–3.9 and 4.9–5.8 GHz. The antenna is suitable to be integrated within the portable UWB devices without EMI interference at WiMAX and WLAN bands.

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TL;DR: Results indicate that the UWB–MIMO antenna covers UWB frequency band of 3.1 – 10.6 GHz except four rejected bands, isolation of better than −18 dB, envelope correlation coefficient of <0.02, and good radiation pattern, making it useful for UWB systems.
Abstract: With quad-band-notched characteristic, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna is introduced in the paper. The UWB–MIMO system has two similar monopole elements and occupies 30 × 45 mm2. By inserting two L-shaped slots, CSRR and C-shaped stubs, four notched bands are achieved (3.25–3.9, 5.11–5.35, 5.5–6.06, and 7.18–7.88 GHz) to filter WiMAX, lower WLAN, upper WLAN, and X-band. Meanwhile, the isolation is obviously enhanced with three metal strips on the ground plane. Results indicate that the antenna covers UWB frequency band of 3.1 – 10.6 GHz except four rejected bands, isolation of better than −18 dB, envelope correlation coefficient of <0.02, and good radiation pattern, thus making it useful for UWB systems.