In this paper, a single-fed high-gain circularly polarized microstrip antenna is proposed. The circular polarization is obtained by two unequal-length arc-shaped radiation patches, which excites two orthogonal linearly polarized modes with a 90° phase difference. The antenna is excited by coaxial feed. The proposed circularly polarized antenna consists of two arc-shaped radiation patches and a ground plane, which has a simple structure and a higher gain than 10.0 dB. The antenna is fabricated and measured to verify the design. The measured results are in good agreements with the simulated ones. The measured results show that the impendenceb and width (IBW) for S₁₁<-10 dB is 16.7% (3.78-4.47 GHz), and the axial-ratio bandwidth (ARBW) for AR<3 dB is 3.6% (4.09-4.24 GHz). Further, the gain from 4.09 to 4.24 GHz is higher than 10.0 dBi. The antenna radiation pattern performs well over the whole band, and the peak gain can reach 10.67 dBi at 4.11 GHz. It is a good candidate for advanced wireless communication systems.

The scattering problem of time-harmonic electromagnetic plane waves by an impedance and a dielectric ellipsoid is considered. A low-frequency formulation of the direct scattering problem using the Rayleigh approximation is described. Considering far-field data, an inverse electromagnetic scattering problem is formulated and studied. A finite number of measurements of the leading-order term of the electric far-field pattern in the low-frequency approximation leads to specifying the semi-axes of the ellipsoid. The orientation of the ellipsoid is obtained by using the Euler angles. Corresponding results for the sphere, spheroid, needle and disc can be obtained considering them as geometrically degenerate forms of the ellipsoid for suitable values of its geometrical parameters.

In this paper, we present a broadband flexible RFID sensor tag antenna to detect the concentration of aqueous solutions. The proposed RFID tag antenna sensor with a T matching network is based on a printed dipole whose arms are loaded with circular disk patches. The structure is printed on a Kapton polyimide flexible substrate. The sensing mechanism of the RFID tag antenna is based on the change of sensitivity of the RFID tag antenna that occurs with the variation of aqueous solution concentration. The proposed sensor is designed using CST Microwave studio, and its various parameters are optimized in order to have a broadband impedance matching that covers the entire RFID band (860-960 MHz). The experimental setup is small, rapid, contactless, and inexpensive. Results are presented for NaCl and sugar aqueous solutions with concentrations ranging from 0% to 80%.

In order to reduce far-end crosstalk between two differential line pairs of microstrip, this paper proposes a method of reducing far end crosstalk by polarity inversion. In this way, the signal line is placed in the middle of PAD of one capacitor to achieve polarity reversal at the AC coupling capacitor of the differential line. The simulation results show that, in this way, the far end crosstalk can be reduced by 63.6%, and this method of far end crosstalk suppression has an effect on both pairs of differential lines.

A novel technique for designing a dual-band reconfigurable aperture coupled cylindrical dielectric resonator antenna is introduced here. The design is based on loading an aperture coupled cylindrical dielectric resonator antenna with a varactor diode located along the lines of the feed network. Loading the antenna with the varactor shifts the first and second resonant frequencies of the antenna. The resonant frequency can be continuously shifted from 4.75 GHz to 4.96 GHz in the lower band, and the resonant frequency of the higher band is shifted from 6.31 GHz to 6.40 GHz as the varactor diode bias voltage is increased from 1 V to 5 V. The proposed antenna offers a stable broadside radiation pattern at both bands and across the entire tunable frequency range for different bias voltages. The parametric analysis on the slot position is done to control the first and second resonant frequencies of the dual-band antenna. The proposed antenna plays a vital role in C-band (4 GHz-8 GHz) applications.

Through-wall imaging (TWI) is one of the useful applications nowadays in microwave tomography field. Reconstructing image of an object becomes more challenging when it is obscured by walls. In practice, the inclusions of noise worsen the reconstruction results. In this paper, Forward-Backward Time-Stepping (FBTS) in time inversion technique is utilized and integrated with Wall Direct Subtraction (WDS) method to reconstruct unknown object behind walls. The investigation includes two types of walls that are homogeneous and heterogeneous. The object is surrounded by closed walls. With noise added in the setup, Singular Value Decomposition (SVD) and Savitzky-Golay (SG) filtering method are used to eliminate the noise and enhance the reconstructed image of an object. The results show that WDS integrated with FBTS has successfully mitigating wall clutter from both homogeneous and heterogeneous walls, and also improves image reconstruction of a hidden object. Further, by using the proposed noise reduction method, lower MSE values can be achieved.

A wideband microstrip open-slot antenna with dual-frequency dual-sense circular polarization (CP) is presented in this paper. A bent feeding structure and three radiating slots, including a modified cross-shaped, an inverted F-shaped, and an inverted L-shaped slots, are designed to excite two orthogonal electric fields with a quadrature phase difference for a radiating right-hand circularly polarized (RHCP) wave at 2.5 GHz and left-hand circularly polarized (LHCP) wave at 3.3 GHz. To improve the axial-ratio (AR), a bent parasitic element is introduced near the microstrip line. Multiple resonances are merged to achieve a large bandwidth of 2620 MHz (104.8%) from 2.2 GHz to 4.82 GHz. The measured AR bandwidths are 460 MHz (18.4%) at the lower band (2.5 GHz) and 2150 MHz (65.1%) at the upper band (3.3 GHz).

This paper studies a computationally efficient algebraic graph theory engine for simulating time-domain one-dimensional waves in a multi-segment transmission line, such as for reflectometry applications. Efficient simulation of time-domain signals in multi-segment transmission lines is challenging because the number of propagation paths (and therefore the number of operations) increases exponentially with each new interface. We address this challenge through the use of a frequency-domain, algebraic graphical model of wave propagation, which is then converted to the time domain via the Fourier transform. We use this model to achieve an exact, stable, and computationally efficient (O(NQ), where N is the number of segments and Q is the bandwidth) approach for studying one-dimensional wave propagation. Our approach requires the reflection and transmission coefficients for each interface and each segment's complex propagation constant. We compare our simulation results with known analytical solutions.

Various formulations of the inverse equivalent surface-source problem and corresponding solution approaches are discussed and investigated. Starting from the radiation integrals of electric and magnetic surface current densities, the probe-corrected inverse equivalent source formulation is set up together with different forms of side constraints such as the zero-field or Love condition. The linear systems of equations resulting from the discretized forms of these equations are solved by the normal residual (NR) and normal error (NE) systems of equations. As expected and as demonstrated by the solution of a variety of inverse equivalent surface-source problems, related to synthetic as well as realistic antenna near-field measurement data, it is found that the iterative solution of the NE equations allows for a better control of the solution error and leads in general to a slightly faster convergence. Moreover, the results show that the incorporation of the zero-field condition into the solution process is in general not beneficial, which is also supported by the structure of the NE systems of equations. If desired, Love surface current densities, or just fields in general, can more easily be computed in a post-processing step. The accuracy of the obtained near-fields and far-fields depends more on the stopping criterion of the inverse source solver than on the particular choice of the equivalent surface-source representation, where the zero-field condition may influence the stopping criterion in a rather unpredictable way.

This paper presents design analysis of a compact CPW fed Wearable Textile Antenna with Dual Band notched characteristics for UWB applications. The proposed wearable textile antenna is designed on two different dielectric substrates; leather and denim with copper foil as conducting element. The performances of the designed textile antenna are compared on two substrates. Band-notched filtering characteristics are achieved by inserting semicircular split ring resonators on the conducting element. The first notch band is obtained from 2.3 GHz-2.5 GHz for Bluetooth application band, and the second notch band is obtained from 3.3 GHz-3.6 GHz for WiMAX application band. The simulated and measured frequency results show that the antenna has an impedance bandwidth of 1.8-10 GHz and reflection coefficient less than -10 dB, except at the two eliminating bands. The proposed antenna is designed and simulated using Ansys HFSS Electromagnetic Simulator. The prototype of the antenna has been developed on the denim substrate, and its performance is measured and compared with the simulated ones.

The paper presents a new coplanar waveguide (CPW)-fed ultra-wideband (UWB) dual circularly polarized (CP) slot antenna. For realizing UWB, a wide slot is introduced in the ground plane of the proposed antenna. The circular polarizationis achieved by introducing a semi-circular stub in the square ground plane. The antenna contains two symmetrical CPW-fed ports at left and right edges to generate dual circular polarization. The evolution steps of the proposed CP antenna are presented, and antenna parameters are optimized to obtainthe desired level of isolation, return loss, and axial ratio bandwidth (ARBW). The measured impedance bandwidth (S₁₁ ≤ -10 dB) of the antenna is 13.5 GHz (2.5-16 GHz); 3-dB ARBW is 75.23% (2.67-5.89 GHz); and isolation greater than 17 dB is obtained in the CP band. The designed dual feed CP antenna has low profile, light weight, compact size, and could be suitable for polarization diversity applications for reducing the effect of multipath fading.

A simple, compact, and capacitively coupled triple band planar inverted F antenna for wireless applications is presented in this paper. By arranging two metal patches in a stacked manner and using capacitively coupled feeding method three resonant modes are generated. The three operating bands 1.8 to 1.9 GHz, 2.5 to 2.6 GHz, and 3.3 to 3.4 GHz for GSM 1800, LTE 2500, and WiMax applications, respectively with -10 dB return loss bandwidths of 5.4%, 3.9%, and 2.98% around the resonances. The antenna occupies a size of 40 mm × 5 mm × 6 mm and is printed on an FR4 epoxy substrate of dielectric constant 4.3.

This paper presents a novel Circularly Polarized (CP) microstrip array antenna with circular shape and slotted by an elliptical ring for X-band communication. This array antenna consists of 4 paths. Each patch is designed with a unique model, and the purposed antenna is mainly circular-shaped. An elliptical ring slot is set at the center of the circular-shaped patch. And a pair of triangle shapes employed as truncation factor is placed at the edge of the circular-shaped antenna. This microstrip array antenna is developed by 2 × 2 patches in a sequential rotation mode with relative phases 0˚, 90˚, 180˚ and 270˚. Total dimension of this array antenna is 60.92 mm × 60.92 mm. The simulated result shows a good agreement with minimum requirement. The center frequency of the antenna design is 8.2 GHz with low-frequency at 8 GHz and high frequency at 8.4 GHz. The proposed antenna produced under -10 dB S₁₁ of 21.9%, maximum gain of 12.47 dBic at the center frequency, and axial ratio bandwidth obtained 12.2%. Simulated result has been validated by fabrication and measurement, then the structure of the antenna design is fabricated on NPC-H22A with a thickness of 1.6 mm and dielectric constant of 2.17. Complete investigation and experimentation are presented in the next sections.

Recently, manipulation and measurement of quantum states, especially in quantum cavities, have attracted the attention of many researchers in different fields, such as: quantum optics, quantum information, quantum computation, and so on. In this paper a non-demolition method for the measurement of squeezing parameter via atomic Mach-Zehnder interferometer, is presented. An experimental setup was also proposed which included two quantum cavities, in different arms of an atomic Mach-Zehnder interferometer. Each quantum cavity was settled between two classical cavities. Quantum cavities were contained entangled states with arbitrary squeezed photons. It is shown that the outgoing atomic states of Mach-Zehnder interferometer carry on the properties and situation of quantum states of the cavities. The squeezing parameter of photonic state forone of cavities, is obtained by the detection of excited and non-excited probabilities of Mach-Zehnder interferometer's outgoing ports, for a train of incoming two-level Rydberg atoms.

A high isolation broadband dual-polarized omnidirectional antenna comprising two low profile orthogonally polarized omnidirectional radiating elements is presented. A modified monopole using loadings to broaden impedance bandwidth is applied to vertical polarization (VP), while four printed concentrically arranged Yagi-Uda-like antennas are employed for horizontal polarization (HP). Both the simulated and measured results indicate that the operating bands of the proposed antenna with its reflection coefficient less than -10 dB are 1.48 to 3.16 GHz for VP and 1.69 to 2.7 GHz for HP. A good port isolation larger than 40 dB and omnidirectional patterns with the out-of-roundness less than 2 dB in horizontal plane are obtained. This paper explains the radiation mechanism by investigating the simulated surface current distributions for VP element and establishing a radiation model for HP element, and also analyzes the performance of the proposed antenna. This antenna design can be applied to 4G (LTE) communication system.

Last decade has witnessed dramatic advancements in wireless charging distance of magnetic resonant coupling wireless power transfer (MRCWPT) for various portable electronic devices. Driven by the demand of cost-effective and compact system working for multiple receivers, a novel omnidirectional MRCWPT system with a single wire wound spiral transmitter and a single power source is proposed in this work. Besides, an equivalent circuit model is established to derive the power transfer efficiency (PTE) of this novel MRCWPT system. Finite element simulation results have shown that the magnetic field distribution for the proposed model is uniform in all directions. And the PTE of the system depending on the distance between the transmitter and receivers is demonstrated to be independent of the receiving angles. Finally, the theoretical analysis of the simulation results is verified by practical experimental results, which shows that the PTE of the system reaches 60% at the distance of 160 mm and the resonant frequency of 15.5 MHz.

Feature extraction is of significant importance for final results of the through-wall detection procedure. High resolution range profile (HRRP) is related to target reflectivity coefficients which can be used as a new feature for object detection. Compressive sensing (CS) is an emerging technique which enables a sparse signal to be recovered using much fewer measurements. This method can provide a novel way for achieving the HRRP since the target reflectivity coefficients are often known to be sparsely distributed in range cells. In this paper, after a set of input-output patterns that consist of target position and HRRP are obtained, through-wall detection problem is reformulated into a nonlinear regression one, which can be solved by support vector machine (SVM). Numerical simulations demonstrate that the prediction accuracy of target position is related to the number of range cells, the number of observations, and signal-to-noise ratio (SNR). Furthermore, the proposed method performs better than the one using signal amplitude as a feature in terms of smaller estimation error and shows better robustness against noise.

The ability to predict rain characteristics at small space-time scales is important, particularly in the planning, design, and deployment of wireless networks operating at frequencies above 10 GHz. For wide area networks, high space and time resolution rainfall data are often not available, and the cost of such measurements is prohibitive. This paper thus presents a new approach to address this problem using rain radar measurements to obtain rain estimates at finer resolutions than that available from the original measured data. This paper proposes three innovative methodologies: 1) the approach is not directly applied to measured rainfall rate data but focuses on the parameters of fitted lognormal distribution parameters and/or computed rain characteristics for each location; 2) to facilitate the application in wireless communication networks operating above 10 GHz, a set of databases and contour maps of rain parameters spanning North West Europe have been created. These conveniently and efficiently provide rain parameters for any location within the area under study; and 3) the proposed 3D space-time interpolation approach can extrapolate rain parameters at space-time resolutions that are shorter than those found in NIMROD radar databases. The results show that the approach presented in this paper can be used to provide {1 km, 5 mins} space-time rain rate resolution from {5 km, 15 mins} data for the whole North West Europe with error percentages of less than 4%. This is far superior to estimates provided by the International Telecommunication Union recommended model.

We propose a planar chiral metamaterial (PCMM), which can function as a triple-band polarization angle independent 90° polarization rotator. The unit cell of the PCMM is composed of bi-layered mutual twisted Fermat's spiral structure (FSS) resonators with four-fold rotation symmetry. The simulated and measured results show that the PCMM can work in triple-band and convert a linearly polarized (y-/x-polarized) wave to its cross-polarization (x-/y-polarized) or experience a near 90° polarization rotation with a polarization conversion ratio of over 90%. The electric field and surface current distributions of the unit-cell structure are analyzed to study its physics mechanism. Compared with previous CMM-based rotator, our design has more operation frequencies in a single PCMM structure, a relative thinner thickness, and higher Q-factor. Good performances of the PCMM suggest promising applications in the polarization rotator or convertor that need to be integrated with other compact devices.

Moving target ship imaging in large sea area has always been the focus of military and civilian attention. Due to the limitation of pulse repetition frequency (PRF), there is a contradiction between wide mapping band and azimuth accuracy. The nonlinearity of PRF can also cause discontinuity of mapping band. Therefore, this paper proposes a method of digital beamforming-scan on receiving (DBF-SCORE) beam scanning based on airborne phased array radar to achieve the requirement of scene mapping band with lower PRF. The adaptive Capon spectrum estimation is used to dynamically adjust the beam pointing so that it can always point to the moving target for accurate imaging. Considering the nonuniform sampling of the transmitting pulse period of the antenna, the azimuth nonuniform Fourier transform (NUDFT) algorithm is used to re-sample the nonuniform periodic signal of the multi-channel receiving antenna and obtain the uniform spectrum signal. Finally, fine focusing of moving target is achieved by local phase gradient algorithm (PGA) algorithm, and accurate imaging of moving target in large sea area is realized. The validity of the algorithm can be verified by simulation and real data imaging, which can be used for reference in phased array SAR imaging of moving targets.