A compact and hexagon-shaped microstrip patch antenna operating in three bands is described in this paper. Multiband functionality of the antenna is achieved by adding two inclined strips and cutting modified slots on the radiating patch. The antenna consists of a hexagonal patch and partial ground plane, has the total dimensions of 15×17 ×1.6 mm3, operates over three frequencies 5.40 GHz, 6.76 GHz, and 8.82 GHz for WLAN, TV satellite broadcasting, WiMAX (5250-5850 MHz), IEEE 802.11a (5.47-5.725 GHz), 5G Unlicensed band (5.2-5.7 GHz), weather monitoring, and radar applications. This antenna has the novelty that it can also be used as a reconfigurable antenna, and the notched bands can be controlled. Simulation of the proposed antenna is carried out using HFSS-15 software. To verify the simulated results, and a prototype of the proposed antenna is fabricated. After measurement, simulated and measured results are in good agreement.
In this manuscript, a modified spokes wheel shaped two port MIMO (Multi-Input-Multi-Output) antenna with stub loaded ground plane has been presented and experimentally analysed for multiband and EU (European Union) 5900 to 6400 MHz for future 5G mobile terminal applications. The proposed MIMO antenna consists of two radiating patches, and its ground plane is modified to achieve the multiband characteristics as well as enhanced isolation. Initially, a rectangular notch, at the center of ground plane (Ground-1), is employed and reveals four resonant points. Further, the ground plane is modified again by employing two inverted L-shaped stubs along with a series of horizontal rectangular stubs (Ground-2) for enhancing the isolation and reducing the mutual coupling between the elements of proposed MIMO antenna. The antenna with ground-2 exhibits seven frequency bands (S11 ≤ -10 dB) 2.2, 6.0, 7.9, 9.6, 11.1, 12.7, and 15.6 GHz with corresponding isolation (S12/21) -19.47, -31.22, -34.63, -30.05, -27.16, -39.08, and -22.28 dB. Diversity performance parameters of the proposed MIMO antenna such as ECC, DG, CCL, TARC, and MEG are also in acceptable limits at each operational frequency band. The proposed MIMO antenna is designed and fabricated on a low cost FR4 glass epoxy substrate, and the simulations are carried out by using FEM based Ansys HFSS V13 simulator. Simulated and measured results are compared and found in good agreement with each other.
A four-stage switched beam antenna array at millimeter-wave (mm-wave) frequencies is designed, fabricated, and experimental results are demonstrated. A novel rectangular loop dipole antenna (RLDA) applying the quasi Yagi-Uda concept is designed to achieve high gain and wide bandwidth with end-fire radiation. This RLDA with director has a return loss better than 10 dB over a frequency range of 32 GHz to 37 GHz and a peak gain of 8.5 dB. The proposed high gain end-fire RLDA antenna in combination with a 4x4 Butler Matrix(BM) creates the switched beam configuration and generates four beams in the directions of 15˚±2˚, -45˚±4˚, 38˚±2˚, and -15˚±1˚ at 33.5 GHz, 34.5 GHz, and 35.5 GHz with successive input port excitation. The switched beam configuration has overall dimensions at 34.5 GHz is 26 mm x 25.8 mm (3.03λ x 3.0λ).
This paper reports the investigation of a one-dimensional (1D) photonic crystal (PhC) sensor with improved performance for detecting different categories of cancer cells. The sensing region consists of a vertical slot (VS) introduced inside the periodic Bragg mirror. The structure operating principle is based on the change of the refractive index (RI) of the analyte incorporated in the VS, which leads to the shift in the resonant wavelength peak. The sensing properties have been numerically simulated and analyzed using the transfer matrix method (TMM). The study shows that the optimization process of the structure tends to enhance sensitivity. From the result of the numerical simulation, it is found that the final optimized sensor exhibits the higher sensitivity of 3201 nm/RIU than other similar devices. We believe that the obtained results will be valuable for designing highly sensitive PhC sensors.
A novel two-element UWB-MIMO ground antenna is designed by using the theory of characteristic modes. The proposed antenna has a simple and compact coplanar structure, which consists of a rectangular metal ground, a four-stage stepped patch, a double L-shaped patch with a corner cut and a rectangular substrate. By analyzing the most relevant characteristic modes of the metal ground in UWB, the expected characteristic modes are excited by the capacitive coupling elements and the hybrid loading of the capacitive and inductive coupling elements, so as to reduce the size, broaden the bandwidth and improve the isolation. The simulated and measured results show that the proposed antenna obtains ultra-wide impedance bandwidths (2.7-12.6 GHz for Port 1 and 3.0-11.0 GHz for Port 2). Furthermore, the proposed antenna also achieves high gains (3.1-7.3 dBi for Port 1 and 2.7-5.8 dBi for Port 2), stable radiation patterns and good diversity characteristics (the minimum isolation > 16 dB, the envelope correlation coefficient < 0.01, the channel capacity loss < 0.08 bps/Hz, and the total active reflection coefficient < -4.1 dB, etc.) in the whole impedance bandwidth. The research results can provide a useful reference for the design of UWB-MIMO ground antennas based on the theory of characteristic modes.
Wideband designs of proximity fed regular shape microstrip antennas using bow-tie and H-shape ground plane profile are proposed in 1000 MHz frequency range. The modified ground plane alters the quality factor of the patch cavity which enhances the impedance bandwidth. In terms of the results obtained for bandwidth and gain together, circular and square patches backed by bow-tie shape ground plane, followed by circular patch backed by H-shape ground plane yield optimum results. For substrate thickness of 0.097λg, against the conventional ground plane, bow-tie shape gives 12% and 24% bandwidth increment for circular and square patches, respectively, and H-shape ground plane yields bandwidth increment by 17% in circular patch. All these wideband designs offer peak gain around 6 dBi with a broadside radiation pattern. Further, modified ground plane profile helps in optimizing the proximity fed antennas on lower substrate thicknesses. Amongst all the configurations, for ~0.03λg reduction in the substrate thickness, SMSA using bow-tie shape ground plane yields 19% increase in the impedance bandwidth against the equivalent thicker substrate design with a peak broadside gain of above 6 dBi. Thus, proposed modified ground plane antennas yields bandwidth improvement but for a smaller substrate thickness.
Aiming at the shortcomings of complex broadband transmitter/receiver systems and inflexible bandwidth control in the existing inverse synthetic aperture radar (ISAR) imaging systems, in this paper, a novel two-dimensional imaging method based on frequency diverse ISAR (FDISAR) is proposed by combining frequency diversity technique with inverse synthetic aperture technique. In the imaging process, FDISAR is different from the stepped-frequency ISAR, which needs to transmit the same burst at different observation moments. Once the bandwidth is determined, the bandwidth of the subsequent burst synthesis cannot be changed, which reduces the flexibility of the radar system. In this method, single-frequency signals of different frequencies are transmitted to the target at different observation times, and the wideband signals are synthesized using the frequencies at different observation times to obtain the resolution capability in the range direction. In addition, the relative motion synthetic aperture of the target and radar is used to obtain the azimuth resolution capability, and finally the two-dimensional imaging capability of the moving target is formed. Specifically, we established an ISAR imaging model based on frequency diversity to synthesize a broadband signal, and used an improved backward projection algorithm (BP) to complete the two-dimensional imaging of the target. On this basis, the influence of the transmission signal frequency selection on the imaging quality is analyzed, and the half-power resolution in range and azimuth directions is derived. Furthermore, in order to eliminate side lobes and improve imaging quality, we combined compressive sensing (CS) theory with a BP imaging algorithm based on compressed sensing to obtain high-quality target 2D images. Simulation and actual measurement results show that FDISAR can achieve two-dimensional imaging of moving multi-scattering point targets. The application of this method is of great significance for reducing the complexity of the ISAR imaging system and improving the flexibility of the system's control bandwidth resources.
We presented a miniaturized defected ground structure-based millimeter-wave (MMW) contemporary MIMO antenna for 5G smart applications devices. The proposed MIMO antenna offers many advantages including high gain, compactness, planar geometry, wide impedance bandwidth, and reduced mutual coupling effects performance. The top layer of the proposed four-port MIMO antenna design comprises 1x2 rectangular patch array structures, with each placed at the middle of a 20x20 mm2 substrate of material (RO4350B) having thickness of 0.76 mm and loss tangent of 0.0037. For miniaturization and better performance, both the ground layer and radiating patches are defected with slots of a rectangular shape while an E-shaped slot is placed at the center of the ground plane. The operating impedance bandwidth of the proposed antenna ranges from 26.4 to 30.9 GHz incorporating the dominant portion of the mm-wave band. The proposed MIMO antenna is also characterized by the fundamental MIMO performance metrics such as Envelope Correlation Coefficient (ECC) which is less than 0.12 for any two-element array that encounters the mandatory standard of <0.5, high Diversity gain (DG) reaching its ideal value of 10 as well as minimum isolation of -19 dB with a total efficiency of 85% at 28 GHz. These characteristics make the proposed compact four-port MIMO antenna one of the best candidates to be used in 5G portable devices.
In this paper, impedance modeling is presented for analyzing the metallic loading effect on the performance of a split ring resonator (SRR) antenna in (2.4-2.5)/(5.1-5.8) GHz frequency bands. Two SRR antennas of rectangular and circular rings have been designed on ANSYS HFSS software, and their return losses are obtained as -16.63/-25.26 dB at 2.7/5.8 GHz and -10/-20.09 dB at 2.2/5.2 GHz, respectively. Then the metallic loadings are incorporated in both rectangular and circular SRR antennas, which move the peak resonant frequency to 2.5/5.1 GHz with simulated return losses of -14.39/-22 dB for rectangular SRR antenna and to 2.6/5.1 GHz with -17.64/-11.10 dB, respectively for circular SRR antenna. Then, to analyze the effect of metallic loading on SRR antenna performance, a set of equations are derived from the equivalent circuit of the SRR antenna without and with metallic loading to evaluate the lumped elements values. The circular SRR antenna with metallic loading is fabricated, and its measured return loss is found to be -17.94/-15.76 dB at 2.415/5.23 GHz. The lumped component values are calculated from the measured return loss using the derived equations, and these values are compared with those obtained from the simulated return loss for circular SRR antenna. A shift in resonant frequencies towards the desired bands is observed due to the inductive effect of the metallic loading. The axial ratio values higher than 15 dB confirm that the proposed SRR antennas with metallic loadings are linearly polarised. The 2D patterns in E-plane and H-plane, as well as 3D far-field patterns, confirm an omnidirectional radiation pattern for circular SRR antenna, which is useful for WLAN applications.
In this paper, we present a waveguide-fed hollow cylindrical dielectric resonator antenna (CDRA) with dual-band operation and its modified structure for wider bandwidth and enhanced gain operation. The distinctive nature of the structure provides two bands having resonant frequencies at 8.46 GHz and 9.24 GHz with maximum gains of 5.37 dBi and 6.86 dBi respectively with a single dielectric resonator antenna (DRA). The dual-band is achieved due to the resonance of DRA and the air column inside it. Excellent coupling is achieved in both bands. The dual-band structure is modified by changing the volume of the air column inside the CDRA keeping all other parameters constant to result in a wider band and high gain antenna. A bandwidth of 7.9% with a resonant frequency of 9.0 GHz and a maximum gain of 8.14 dBi is obtained for the modified structure.
This paper presents a MIMO antenna system composed of eight wideband horizontal dual-loop antenna elements. Each dual-loop antenna is printed on both sides of a smartphone board. The unit element antenna is designed to operate in the frequency range from 3.2 GHz to 5 GHz. The performance of the MIMO system is then analyzed. The performance of the obtained MIMO system in the frequency range from 3.2 GHz to 4.8 GHz is characterized by input reflection coefficient which is less than -6 dB for all antenna elements, and the isolation between the elements is larger than 15 dB. The total efficiency is greater than 55% over the entire band (3.2-4.8 GHz). Parameters of the multichannel antennas including envelope correlation coefficient (ECC), diversity gain (DG), and channel capacity loss (CLL) are analyzed to evaluate the performance of the MIMO system. The effect of the human hand and head on the performance of this MIMO antenna is also investigated. In addition, the effect of the radiated fields on the human body is also studied. The Specific Absorption Rate (SAR) value is found to be less than 0.8 W/kg. The MIMO system antenna is fabricated and measured. Good agreements are obtained between the simulated and measured parameters. The proposed MIMO system is applicable to the 5G N48, N77, and N78 bands.
A multi-input multi-output (MIMO) antenna system is presented for wireless devices operating at WLAN (2.45, 5.25, and 5.775 GHz) bands. Each of the two antennas in the MIMO system consists of a crescent-shaped monopole whose first part covers the 2.45 GHz band while its second part covers the 5.25 GHz and 5.775 GHz bands. The second part of the monopole is a slot etched in the protruded ground plane between the two antennas. A decoupling mechanism in the form of two interlaced ring-shaped slots is used. The proposed MIMO antenna system is designed on an FR4 substrate with overall dimensions of 40x47.5x1.5 mm and a small edge-to-edge spacing of 7.3 mm between two antennas. According to the measured results, the proposed design covers two frequency bands (2.2-2.83 GHz and 5.03-5.95 GHz) and has a mutual coupling of -20.78 dB at 2.45 GHz and -42.65 dB at 5.55 GHz. The proposed antenna's performance in both simulations and testing indicates that it is a good choice for WLAN applications.
In this paper, a dual-band modified multiple-input-multiple-output (MIMO) antenna with high isolation is presented and discussed. The proposed compact structure (35 × 25 mm2) consists of two monopole elements and defected ground planes to obtain high impedance bandwidth. Two elliptical-shaped patches are placed orthogonal to each other to obtain high isolation, and a neutralization slit is integrated into the ground plane of each element to further improve the isolation between the elements. The measurement results of the proposed structure show satisfactory agreement with the simulation results. The measured bandwidths are 47.05% (2.6-4.2 GHz) and 64.72% (5.11-10 GHz) at S11 ≤ -10 dB which covers bandwidth requirements of WiMAX (3.4-3.6 GHz, 5.25-5.85 GHz), sub 6 GHz 5G band (3.4-3.8 GHz), WLAN (5.15-5.35 GHz, 5.725-5.825 GHz), and X band satellite communication systems (7.25–8.39 GHz). The designed antenna offers a peak gain of about 9.0 dBi and radiation efficiency of about 92%. The measured minimum isolation is greater than 27.3 dB across the dual band with a maximum value of 73.4 dB. The envelope correlation coefficient (ECC) is below 0.0035, channel capacity loss less than 0.37 bits/s/Hz, and peak diversity gain about 10 dBi.
This work proposes a design of rectenna for Wi-Fi energy harvesting application at 2.42 GHz. The proposed antenna includes a modified rectangular patch and two circular radiating elements with partial ground, and adopts a total area of 80 × 80 mm2. With the partial ground structure, the proposed antenna shows a better reflection coefficient (S11) at 2.42 GHz. The proposed antenna is a modified conventional patch antenna that shows its improved suitability for Wi-Fi energy harvesting at the targeted band. For rectenna, an impedance matching circuit based on microstrip transmission lines, radial stubs, and enhanced Greinacher voltage doubler rectifier circuits are designed. The rectifier circuit occupies a total area of 25 × 25 mm2. The antenna part of the rectenna exhibits quite good S11 < -10 dB and 3.94 dB peak gain. To validate the design experimentally, a prototype of the proposed rectenna is also fabricated. The measured result indicates that at the resonant frequency the rectenna achieves the peak efficiency of 78.53%, and the output voltage is 4.7 V at 0 dBm input power.
In this paper, a second-order tri-band balanced bandpass filter (BPF) with multiple transmission zeros (TZs) and compact size is presented. The structure consists of novel stepped impedance square ring loaded resonators (SI-SRLRs), which can excite six resonance modes. For design of SI-SRLR, we analysed the odd-mode equivalent circuit and obtained the electrical lengths from the design graph. Meanwhile, the wider frequency distances between differential modes (DMs) and common modes (CMs) are realized by selecting the proper admittance ratio of SI-SRLR. Then for design of BPF, six TZs are introduced by source-load coupling, which lead to band-to-band isolation of 23 dB. Additional T-shaped stubs and open stubs are loaded on the symmetric plane of SI-SRLR, which result in high CM suppressions of 43 dB, 25 dB and 37 dB at three DM centre frequencies. Finally, a tri-band differential BPF operating at 1.46 GHz, 4.45 GHz and 5.48 GHz is fabricated and measured. The measured 3-dB fractional bandwidths of three passbands are 6.8%, 7.4% and 5.6%. A wide DM and CM stopband suppression of 20 dB is achieved to 14.6 GHz (10f0). The measurements verify well the proposed structure and the design method.
To address the problems of large volume, heavy weight, and inconvenient installation of the shield board of a wireless charging coil (WCC) installed on the body of an electric vehicle (EV), a new shielding method is proposed in this paper. From the perspective of engineering practice, according to the principle of passive shielding, and in line with the vertical direction of WCC with ferromagnetic material shielding, this novel shielding method involves only a low permeability metal shielding ring set around the transmitting coil in the horizontal direction. Using the finite element simulation software COMSOL Multiphysics, the EV model, the magnetic coupling resonance (MCR) WCC model, and the pedestrian body model at the observation point are designed. The influence of the metal shielding ring on the self-inductance and mutual inductance of WCC is calculated. The magnetic induction strength (B) and electric field strength (E) of pedestrian body at observation points before and after adding a metal shielding in the horizontal direction are evaluated, and the electromagnetic exposure safety of a pedestrian body in this electromagnetic environment is analyzed. Compared with the shielding method of only adding ferromagnetic material in the vertical direction and after using new shielding, the maximum B of a human trunk is reduced by 43%, the maximum E reduced by 44%, the maximum B of human head reduced by 44%, and the maximum E reduced by 39%. After adding the metal shielding ring, the maximum B and E of human trunk decreased from 8.56 × 10-1 times and 2.28 × 10-1 times of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limit to 4.89 × 10-1 times and 1.27 × 10-1 times, respectively, and the maximum B and E of human head decreased from 1.62 × 10-3 times and 8.58 × 10-4 times of the ICNIRP exposure limit to 9.18 × 10-4 and 5.25 × 10-4 times, respectively. The simulation results show that the new shielding method can significantly reduce the electromagnetic radiation of the pedestrian's trunk and head central nervous system (CNS) at the observation point. The effectiveness of the shielding method is proven, and this work provides a certain guidance for the engineering design of WCCs.
This paper, using the distributed parameter line model, presents an accurate fault location method based on fundamental frequency positive sequence fault components for EHV transmission line. The method based on positive sequence fault components Extra-High Voltage (EHV) electric transmission line. The method based on the positive sequence fault component is robust to the operating state of the prefault system and fault path resistance. The technique proposed in the paper does not require the fault type, fault phase, and the zero-sequence parameter to be obtained in advance. In addition, due to the use of fault component protection theory, the algorithm itself is not aected by the previous operating state of the system. The method uses a distributed parameter model, which is more accurate in positioning and smaller in error than a lumped parameter model by a large number of simulations. Accurate fault location is important for shortening the fault time and reducing the loss of the fault, so the positioning method proposed can improve the power supply quality and safety. This paper describes the characteristics of the proposed technique and assesses its performance by using Power Systems Computer Aided Design/Electromagnetic Transients including DC (PSCAD/EMTDC).
A dual-element miniaturized multiple-input-multiple-output (MIMO) antenna with a defected ground plane and a tapered microstrip feed line is introduced in this article. It achieves a bandwidth (BW) of 10.8 GHz (7.2-18 GHz), frequency ratio (FR) of 2.5, and average isolation of 15 dB over the entire operating band. The proposed antenna is right hand circularly polarized (RHCP) and achieves an axial ratio of < 3 dB in the frequency band ranging from 7.2 to 8.9 GHz. The performance characteristics of the proposed antenna are analyzed in terms of the envelope correlation coefficient (ECC), mean effective gain (MEG), total active reflection coefficient (TARC), isolation between the ports, and channel capacity loss (CCL), and the values obtained are 0.1607, 9.99 dB, ±3 dB, -11 dB, -7 dB, 0.20 bits/sec/Hz respectively. The proposed MIMO antenna is fabricated on an FR-4 dielectric substrate of dimension 10.6×10.3×1.6 mm3 and has good agreement between simulated and experimental results. The proposed antenna can be used for C, X, and Ku band applications.
A novel staired-slitted flag central resonator based wide band bandpass filter with sharp selectivity and super spurious harmonic suppression is proposed in this paper. Input-output ports based on three line edge coupling with ground plane aperture cutting contribute to the rejection of harmonics in the lower stopband. The spurious harmonic at the upper stopband is rejected with the help of embedded open stub suppression cells. The generation of two transmission zeros at the lower and upper cut-off frequencies are due to the staired slitted-flag main resonator, which contributes to the better selectivity of the filter, and it is verified with the help of mathematical equations. The fractional bandwidth of the developed filter is 107.2% with 7.82 GHz centre frequency. This work demonstrates the design, theory and implementation aspects for the realization of bandpass filters with sharp selectivity and very good spurious suppression.
An optically transparent circularly polarized indium tin oxide based antenna having operability in THz region is proposed in this paper. An E-shaped slot and an I-shaped slot are embedded into an E-shaped radiating E-shaped radiating patch modeled by ITO and conductive carbon nanotube (CNT) on a polyimide substrate to obtain circular polarization. The unequal parallel slits of the E-shaped patch with an E-shaped slot lead to introduce two orthogonal modes, and hence circular polarization is achieved. Besides, integration of a I-shaped slot also helps to create the difference in magnitude of current distribution between the two working modes to get better axial ratio. Due to the high resistivity of indium tin oxide thin film, the patch of the antenna is covered with highly CNT film which improves the overall performance of the antenna. To overcome the limitations of the traditional design process, characteristic mode analysis is carried out which helps to realize and analyze circular polarization generation mechanism effectively. The proposed antenna shows a wide 3-dB axial ratio bandwidth of 9.66%. A reasonable gain of 2.61 dBic is obtained at 1.11 THz with excellent radiation performance. Wide 3-dB axial ratio bandwidth with reasonable gain makes this light weight transparent small-antenna competent for wireless and satellites applications.