This paper presents an unequal-split Bagley power divider that consists of uniform transmission lines and is terminated at different impedances. This divider should be only adjusted by altering the length of the transmission lines. Such alteration of the transmission lines will result in an arbitrary power ratio between output ports. The Bagley divider consists of uniform transmission lines of same characteristic impedance value despite different impedances for input and output port termination. For analysis, two Bagley dividers are considered, one 3-way and one 5-way divider, both with arbitrary power ratio and arbitrary termination impedances. A good agreement can be observed between the simulated and measured results.
A 3D compact printed monopole antenna for most of the wireless communication applications is proposed in this paper. The proposed antenna has dimensions 40×10 ×1.6 mm³; it is based on multi different length arms of E-shaped monopole with modified ground plane coupled with meander line. The performance of the 3D antenna is almost the same as a 2D antenna with reduction in size, and it could be fit in a wireless transceiver device. The size reduction about 25% compared to the 2D planar proposed antenna is realized on a printed circuit board to reduce the fabrication cost. The coupling between the antenna elements broadens the operating bandwidth, which includes most of the wireless commercial service bands, GSM850/ GSM900/ UMTS/ GSM1800/GSM1900/WCDMA2100 802.11b/g/LTE2600 (82 -2690 MHz) as well as 802.11a/n (5150-5825 MHz). The antenna's simulated and experimental results are in good agreement. It is fabricated on a low-cost FR4 substrate and measured to validate the simulation performances. Measured results display that the proposed antenna produces omnidirectional radiation pattern of -6 dB impedance bandwidth at multi operating bands and average gain of 2 dBi over the operating band.
A low-profile superstrate antenna operated at dual-band is proposed using a metasurface (MTS). In order to design the proposed antenna, the MTS as a partially reflective surface (PRS) has a zero degree reflection phase at dual-band and is composed of a substrate, periodic metallic square patches, and rings on one side and periodic metallic meshes on the other side. To satisfy the resonance condition of Fabry-Perot cavity (FPC) at a certain frequency and height of PRS from the ground plane, the reflection phase of the MTS should be controlled by the dimension of the substrate, square patch, square ring, and mesh. In this paper, the planar radiator having a ring patch and a rectangular patch is employed and designed to operate at 2.1 GHz and 5.8 GHz. Also, the height of MTS from the ground plane is 12 mm, which corresponds to about 0.08λ0 and 0.23λ0 at operation frequencies of radiator, respectively. As a result, the gain improvements at 2.1 GHz and 5.8 GHz are measured to be 4.1 dB and 3.2 dB, respectively.
An ultra-wideband frequency selective surface (FSS) for wide incident angles is proposed. Its -3dB bandwidth is from 3.49GHz to 12.13GHz, and the fractional bandwidth exceeds 110%. Some parasitic patches are appended to reduce the deviation of resonant frequency under wide-angle incidence. The proposed FSS exhibits an improved stability when the incident angles are in the range from 0° to 60°. The relative simulated and measured results are provided to validate its effectiveness.
This paper presents a design of microstrip transmitting and receiving antennas to be used for time reversal ultra-wideband imaging applications. The transmitter and receiver arrays are together known as a time reversal mirror (TRM). Based on the properties of time reversal and its imaging applications, an antipodal Vivaldi antenna and a monopole antenna are proposed for the transmitter and receiver designs, respectively. Simulation and measurement results demonstrate the efficiency of the antennas for a time reversal mirror. The overall system is demonstrated for source and target imaging applications.
This paper presents a novel frequency reconfigurable monopole antenna that has switchable notch characteristic at center frequency of 5.3 GHz. The proposed antenna consists of a defective ground structure (DGS) to enhance the impedance bandwidth from 3.17 to 13 GHz. The F-shaped parasitic element with three stubs (two vertical and one horizontal) are located on the back side of the radiating patch to achieve the band rejection characteristics from 4.9 GHz to 5.7 GHz. The metallic ground plane structure is connected or disconnected to the F-shape parasitic element through stubs by means of p-i-n diodes. Experimental demonstration of applications of the proposed antenna structure as 5.3 GHz notched band ultra-wideband (UWB) antenna with all diodes in the OFF-state and as 5.3 GHz radiator for wireless local area network (WLAN) with all diodes in the ON-state is reported. In both the cases, good agreements between measured and simulated return losses, radiation patterns and realized gains are observed.
A novel six-band metamaterial absorber based on four multiple-mode Ω-shaped resonators (MMORs) is presented, analyzed and measured in this paper. The discrete absorption responses, determined by horizontal-oriented and vertical-oriented MMORs, can be combined to add the total number of absorption peaks. Among the six absorption peaks, four absorption peaks are excited by horizontal-oriented MMOR, and the other two are excited by vertical-oriented MMOR. The absorber, composed of a simple resonators-dielectric-sheet sandwich structure, has six distinct near-perfect absorption peaks with the polarization-insensitive characteristic in the range from 2 to 17 GHz. To reveal the physical mechanism, the distributions of surface current and power loss density, and the equivalent circuit model are also investigated at the six absorption peaks. Moreover, the measured results are in good agreement with the simulated ones and show that the average absorption rate of proposed absorber is over 97.21%.
A novel Vivaldi antenna utilizing a tapered slot edge with a stepped structure (TSESS) to achieve miniaturization is presented in this paper. Compared with a conventional Vivaldi antenna of the same size, the proposed TSESS significantly extends the low-end bandwidth limitation and also improves the low-end antenna gain and radiation characteristics. The proposed antenna is fabricated and tested for validating the reliability of the design. The measured results show reasonable agreement with simulated ones. Moreover, a good time-domain response is indicated from the measured group delay, showing that the antenna meets the requirements of a UWB system.
This paper presents a general theoretical analysis of the Wireless Power Transfer (WPT) efficiency that exists between electrically short, Perfect Electric Conductor (PEC) electric and magnetic dipoles, with particular relevance to near-field applications. The figure of merit for the dipoles is derived in closed-form, and used to study the WPT efficiency as the criteria of interest. The analysis reveals novel results regarding the WPT efficiency for both sets of dipoles, and describes how electrically short perfectly conducting dipoles can achieve efficient WPT over distances that are considerably greater than their size.
This paper presents the design and fabrication of a coplanar waveguide (CPW) rectenna using a sequential modular approach. The rectenna is printed on high permittivity, low-loss board ARLON AD1000 (εr = 10.35 and tanδ = 0.0023 @ 10 GHz). The recti er section is realized with a single reverse-biased schottky diode SMS-7630 in reverse topology for which a diode model is obtained at -20 dBm for frequencies F0 = 2.45 GHz and 2F0= 4.9 GHz. The low-pass lter and the impedance matching are synthesized from passive CPW structures. Co-simulation technique is used to overcome CPW simulation limitation and to integrate the diode characteristic. The antenna consists of a circular slot loop antenna with stub matching such that its input impedance is close to 50 Ω. The goal of this work is to design a rectifier to simplify and speed up the fabrication process of a rectenna array. We reduced the number of processes to etch the rectifier on the board and minimized the number of lumped elements. At -20 dBm, simulation of the rectifier with an ideal impedance matching network shows rectification at 2.45 GHz with efficiency of 12.8%. The rectifier and rectenna shows efficiency of approximately 10% at an operating frequency of 2.48 GHz.
In this paper, the design, simulation andmeasurementof a dual-band polarizationinsensitive metamaterial inspired microwave absorber are presented.The unit cell is composed of two concentric closed ring resonator(CRR) structures forming octagonal rings which arecarved on an FR-4 dielectric substrate to give maximum absorption at dual frequencies of 2.09 GHz and 2.54 GHz. At these frequencies, the minimum reflection coefficients of -29.15 dB and -18.76 dB are achieved with absorption rates of 99.88% and 98.67% andnarrow 10 dB bandwidths of 2.62% and 2.76%, respectively. Microwave absorption property of the proposed absorber structure is simulated by setting the perfect electric boundary conditions in four planes whose surface normal vectors are directed perpendicular to the wave propagation direction. These numerical computation settings replicate the rectangular waveguideto be used in the experimental measurements for the comparison between the simulated and experimental results. It is experimentally verifiedby the waveguide measurement method that the absorption rates about 99% are achieved for dual bands with polarization insensitivity, thereby meeting the absorption requirements of LTE-band frequenciesfor a real time microwave absorber based energy harvesting systems.
A frequency reconfigurable patch antenna is proposed. The antenna has a rectangular patch with two meandered slots. It can be switched between four bands using two PIN diodes by altering current distribution across the slot edges. The overall dimension of the antenna patch is 11.51 mm × 8.37 mm and fabricated on an FR4 substrate. The design is investigated by simulation and measurement, and the result includes S11 parameters, radiation patterns, measured directivity and gain. With different combinations of PIN diode biasing conditions, the antenna can be set to 6.80 GHz, 7.34 GHz, 7.80 GHz and 8.18 GHz, which collectively covers a continuous frequency range of 1.80 GHz (- 10 dB band width). The antenna also shows consistent radiation patterns at all the reconfigured frequency bands with an average beam width of about 75°. In the accessible frequency range an average gain of 5.14 dBi and low level of cross polarizations are also recorded. A good agreement between measured and simulated results validates the presented concept of frequency reconfiguration.
To enhance the gain of conventional Vivaldi antenna (CVA), a novel dielectric sheets-covered Vivaldi antenna (DSCVA) is proposed. The dielectric sheets suck energy from the tapered slot region and flare termination region of the CVA, and thus act as surface wave antennas to improve end-fire performances. The CVA, DSCVA as well as the DSCVA with elongated tapered profile (SP-DSCVA) are designed, fabricated and measured. The simulation results are in good agreement with the experimental data. Measurement results show that the gain increase of the DSCVA is up to 5.1 dBi in the range of 3.5-16.5 GHz without increasing antenna length compared to the CVA. More gain enhancement is achieved for the SP-DSCVA. In addition, the half power beamwidths of the CVA as well as the sidelobe levels are improved in both E- and H-planes.
A subject of plasmonic spinphotonics is developed for surface plasmon polaritons (SPPs). Since an electromagnetic field is a vectorial field, it has spinning angular momentum, and thus spin current is one of its degrees of freedom. A spin current density tensor has 24 independent components because of its antisymmetry in coordinate indices. By using the law of conservation of electromagnetic angular momentum (i.e., orbital angular momentum plus spinning angular momentum), the electromagnetic spin current density tensor is derived, and its characteristics are indicated. Since surface plasmon polaritons can exhibit various intriguing optical and electromagnetic effects and have many practical applications, we consider a new potential effect relevant to spin current transfer. The electromagnetic spin current density tensor and its intensity profile are analyzed for SPPs sustained on a metal-dielectric interface. The plasmonic spin on a metal ring and a straight thin metal belt is calculated, and based on this, a nanomechanical effect caused by plasmonic spin current transfer is suggested. It is expected that such a nontrivial nanomechanical effect will be useful in the design of new nanophotonic devices aiming at sensitive, accurate measurement techniques.
A compact Ku-band bandpass filter (BPF) with wide pass-band, compact size and high selectively is presented. The presented BPF is composed of two quarter-wavelength resonators and a dual-mode resonator, resulting in a compact circuit size. The transmission zeros (TZs) located at the lower and upper stopband are achieved by the mixed electromagnetic (EM) coupling and dual-mode resonator, respectively, resulting in a high frequency selectively. The measured results show minimum in-band insertion loss, fractional bandwidth and variation of group delay to be 0.9 dB, 36.2% and 0.12 ns, respectively. Also, the stopband suppression is greater than 28 dB from 5 to 10.3 GHz and 30 dB from 19.5 to 29.5 GHz. The effective circuit size of the filter is 8.43×2.28 mm² (0.63 λg ×0.17 λg, where λg is the guide wavelength of 15.1 GHz.)
The configuration of an infinite planar conductive shield is examined when it is excited by an electromagnetic near field generated by a coil current source as that of a wireless power transfer (WPT) system. The analytical expressions of the electromagnetic field based on the transmission theory of shielding are given for different frequencies and different incidence angles of the near field generated by the coil current, assuming the conductive planar shield placed in the close proximity of the coil. The obtained results are discussed and compared with other traditional analytical and numerical solutions.
In this paper, a compact multiple-input-multiple-output (MIMO)/diversity antenna with WLAN band notch characteristics, high isolation, and good ECC suitable for portable ultra-wideband (UWB) applications is presented. The proposed antenna has optimized dimensions of 29 mm × 38 mm. The antenna consists of two orthogonal circular monopoles with a 50 Ω microstrip feed line. In addition, to enhance the impedance bandwidth, a fractal slot, created using Minkowski fractal geometry, is introduced into the ground plane, which is located on the other side of the substrate, just below the feed line. Good isolation (≥ 21.5 dB) with a fractional bandwidth up to 220% is achieved between antenna elements by introducing two ground stubs and a rectangular slot in the ground plane. A band-notch characteristic in the WLAN band is obtained by etching an elliptical split-ring resonator (ESRR) in the radiator. Moreover, a diversity performance of the antenna in terms of ECC (<0.01) and capacity loss (<0.3 b/s/Hz) is performed. This paper offers, for the first time, a combined effect of fractal geometry and ESRR geometry in an antenna design. Finally, a comparison of the proposed antenna is performed with the UWB MIMO/diversity antennas existing in the literature. These results show the suitability of the presented antenna for portable UWB systems.
This paper presents dosimetry of a high resonance wireless power transfer (HR-WPT) system when the transmitter and receiver are aligned and misaligned. An HR-WPT system with two resonant coils and two feeding loops, operating at 13.56 MHz is designed. The power transfer efficiency of the system, and the electric and magnetic fields are investigated using the method of moments. The power transfer efficiency in misalignment situations can be increased by matching the HR-WPT system. Dosimetry of the HR-WPT system is conducted at the optimum matching condition for alignment and misalignment, to achieve the best power transfer efficiency. The specific absorption rate (SAR) is computed using a two-step approach. In the first step, the magnetic fields generated by the HR-WPT system in the absence of a whole-body voxel human model are calculated using the method of moments. In the second step, the SAR in the human model is calculated using the impedance method, with the magnetic fields computed in the previous step regarded as the magnetic fields incident to the human body. Five exposure scenarios are set: one alignment condition and four misalignment conditions. The SAR computed for the alignment and misalignment cases in the matching condition are compared to each other. The compliance of the system is also investigated using the international safety guidelines. Finally, the maximum allowable powers to comply with the guideline are investigated for the five cases considered. The results show that the SARs observed in the misalignment case are higher than those in the alignment case. These results suggest that the misalignment situation should be considered in addition to alignment, when conducting dosimetry of the HR-WPT system.
We proposed an efficient method to radiate the spoof surface plasmon polaritons (sspps) to the endfire direction, which added two parasitic strips as directors in front of the dipole antenna fed by the sspps structure. The directors were used to enhance the endfire radiation due to its beam modified function. Both simulated and measured results suggest good performance of the proposed antenna in a narrow band from 6.5 to 6.9 GHz with about 7.5 dBi realized gain and a 5 dBi increase in the endfire direction at the center frequency of 6.8GHz reference to the unloaded structure. Also, the surface electric field distributions of the unloaded and loaded sspps antenna were studied to verify the gain enhancement in the endfire direction in physical perspective. Our work tends to have better performance than other related work, such as broader bandwidth and higher realized gain with even greatly simplified design process. The proposed sspps antenna has potential applications in planer integrated circuits and communication systems.
A broadband right-hand circularly polarized (RHCP) cross-type traveling wave antenna array is proposed for High-Rate Close Proximity (HRCP) point-to-point (P2P) wireless communication system at 60 GHz. Instead of low temperature co-fired ceramic (LTCC) technology, a single-layer structure of the proposed 2x1 element antenna array is fabricated with a conventional printed circuit board (PCB) process, to provide low manufacturing cost and low profile (0.05 λ0 at 60 GHz). A wide impedance bandwidth (57-64 GHz, VSWR < 2) and broad RHCP bandwidth (57-64 GHz, axial ratio (AR) < 3 dB) are achieved. The RHCP gain is higher than 6 dBic in the entire operating frequency band (57-64 GHz).
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