In this paper, after a brief review of the previous nonlinear power amplifier (PA) classes including Class-B, Class-F, and Class-J, a novel design theory for high-efficiency and high-linearity microwave power amplifier based on 2nd harmonic component of the drain voltage and current signals is proposed. The new scheme introduces a new nonlinear class which like Class-J tunes only two primary harmonic components but unlike Class-J, the drain voltage is boosted to the maximum four times dc drain voltage. A quasi half sinusoidal waveform for the current and a quadratic sinusoidal waveform for the voltage are thus realized in this class, leading to a minimum waveform overlapping. The new class theoretically provides 93% power efficiency. It is, in fact, an enhanced Class-J with higher power efficiency and better linearity performance.

We present a topology of MIMO arrays of inductive antennas exhibiting inherent high crosstalk cancellation capabilities. A single layer PCB is etched into a 3-channels array of emitting/receiving antennas. Once coupled with another similar 3-channels emitter/receiver, we measured an Adjacent Channel Rejection Ratio (ACRR) as high as 70 dB from 150 Hz to 150 kHz. Another primitive device made out of copper wires wound around PVC tubes to form a 2-channels ``non-contact slip-ring'' exhibited 22 dB to 47 dB of ACRR up to 15 MHz. In this paper we introduce the underlying theoretical model behind the crosstalk suppression capabilities of those so-called ``Pie-Chart antennas'': an extension of the mutual inductance compensation method to higher number of channels using symmetries. We detail the simple iterative building process of those antennas, illustrate it with numerical analysis and evaluate there effectiveness via real experiments on the 3-channels PCB array and the 2-channels rotary array up to the limit of our test setup. The Pie-Chart design is primarily intended as an alternative solution to costly electronic filters or cumbersome EM shields in wireless AND wired applications, but not exclusively.

This article proposes a novel ship detection method for high-resolution SAR images. Our goal is to look at this question from a information geometry point of view. The method consists of two steps: construction of revised metric and Riemann structure, and extraction of targets. For the first step of the process, a revised metric is introduced on Gamma 2-manifold. We construct a special Riemannian structure by using the proposed metric. For the second step, the regions of interest (ROIs) are extracted out based on the Riemann structure. Experimental results of the detection method on SAR images show that the algorithm presented is effective.

Metamaterials left-hand negative refractive index has remarkable optical properties; this paper presents the results obtained from the study of a flat metamaterial lens. Particular interest is given to the interaction of electromagnetic waves with metamaterials in the structure of the lens Pendry. Using the new approach of the Wave Concept Iterative Process (WCIP) based on the auxiliary sources helps to visualize the behavior of the electric field in the metamaterial band and outside of its interfaces. The simulation results show an amplification of evanescent waves in the metamaterials with an index of n = -1, which corresponds to a resonance phenomenon to which the attenuation solution is canceled, leaving only the actual growth of these waves. This amplification permits the reconstruction of the image of the source with a higher resolution.

In this paper, a compact reconfigurable monopole antenna is proposed working at three different frequencies depending upon the condition of the optical switch. The proposed reconfigurable antenna in the state of ON switchhas resonant frequencies of 2.45 GHz and 5.4 GHz covering the band of 1.8-2.7 GHz (Wi-Fi) and 5.26-5.99 GHz (WLAN) respectively. The same antenna during OFF state of switch operates only at 3 GHz covering the band of 2.49-3.84 GHz. The proposed multiband reconfigurable antenna is designed and fabricated on an FR-4 substrate having relative permittivity of 4.4, loss tangent of 0.02 and thickness of 1.6 mm. The antenna is fabricated and tested in the laboratory to validate the simulated results. A good agreement between the simulated and measured results is obtained in term of radiation pattern and return loss. The performance of the reconfigurable antenna under both states of switch is examined on the basis of the antenna parameters such as return loss, radiation pattern and gain.

This article takes account of the radiation feature of rivers in synthetic aperture radar (SAR) images and proposes a novel automatic approach to detect highway bridges by combining statistical and topology features. The proposed method consists of two steps. In the river-extraction stage, the classification techniques are applied to water extraction according to the statistical and gray-leveled features. In the bridge-extraction stage, bridges are then detected in this binary image by using a topology-based approach. Experimental results show that the proposed method can be implemented with high-precision highway-bridge extraction, feature analysis, and bridge recognition.

Two novel wire transmitarrays, which are designed using a pair of co-joined L-shaped probes, have been developed for X-band mobile communications. By adjusting the orientation of the L probes, the polarization of the transmitting wave can be easily made either vertical or horizontal. Floquet method has been used for characterizing the transmission responses, and both transmitarray unit cells are found to have achieved a phase range of greater than 380° and a linear phase sensitivity of 44.5°/mm. Wide -1 dB gain bandwidth larger than 10% is achievable in both the vertically and horizontally polarized full-fledged transmitarrays, with radiation efficiency of ~90%. The proposed transmitarrays have low radar cross section, which can be used for military applications.

The propagation characteristics of a composite right/left-handed (CRLH) waveguide loaded with air-filled double ridge corrugations (DRCs) is studied intensively in this paper. It is analyzed from the perspective of electromagnetic (EM) fields other than equivalent circuit method used by many other CRLH structures. First, the EM fields inside the CRLH waveguide are derived theoretically based on the EM fields in the rectangular waveguide and the DRC, as well as the boundary conditions on the interface, respectively. Then the propagation characteristics of the CRLH waveguide including the dispersion relation, surface current and transmitted power are determined according to the EM fields. The properties of the surface current are focused on for analyzing the application possibility of this CRLH waveguide to the leaky-wave antennas (LWAs). The transmitted power of the CRLH waveguide is calculated to demonstrate the high power capacitance of this CRLH waveguide. All the theoretical results are veried through full-wave simulations.

A portable spectra detection system has been developed to enable reflection measurement. This system is mainly composed of spectrometer, LED source and five optical elements. The size of the optical system is about 126 mm × 72 mm × 30 mm. The system covers a range of 340 nm-820 nm, and the spectral resolution is 6.0 nm. Based on the detection system, two example applications for ripeness detection and real-finger identification are carried out to demonstrate the system performance. The detection time is less than 1 second, and a satisfactory agreement was observed between detection results and realistic situation.

In this paper, a novel compact ring resonator based bandpass filter with a second harmonic rejection capability is proposed. The proposed bandpass filter uses a stepped-impedance open stubs and a stepped-impedance ring resonator at feeding lines. Stepped-impedance open stubs are used to obtain a better rejection level in the second harmonic-frequency band. Ring resonator's radius is calculated by examining and solving the eigenvalue equation of the ring resonator. Firstly, Sierpinski second order curve is used to achieve size reduction of about 66 % and 71 % compared to conventional microstrip ring bandpass filter inner and outer areas, respectively. Sierpinski curve is chosen because of its symmetry and its suitability for orthogonal feeding lines and open stubs incorporation without using any additional space. Referring to resonant rejection value, the proposed first Sierpinski structure -15 dB simulated fractional bandwidth is 5.6 % at 1.505 GHz and with rejection of -0.16 dB. Transmission zeros at 2.25 GHz and 3.78 GHz are obtained. Secondly, stepped-impedance open stubs are added to the resonator ports to add another transmission zero at 3.84 GHz. At 2.9 GHz, second harmonic band, the proposed structure achieves rejection of - 6.7 dB instead of -1.7 dB for the conventional one. The proposed structure -15 dB simulated fractional bandwidth is 3 % at 1.42 GHz. Innovation is achieved by the simplicity of inserting the transmission zeros, controlling zeros rejection values, incorporating stubs and orthogonal feeding lines in the same resonator area and reasonable power capability of the proposed structure. The proposed bandpass filter's prototype is fabricated using FR4 material, and a good agreement is found between simulated and measured results for return loss and rejection values. The proposed structure is very suitable for L-band applications.

A circular slotted elliptical patch antenna with an elliptical notch in ground for L-band and S-band application is presented. The proposed antenna consists of an elliptical patch with a circular notch on the top layer of a substrate, and a wide elliptical slot and an elliptical notch with two symmetrical slots on the bottom layer of the same substrate. The proposed antenna was fabricated on an FR-4 substrate (tan(δ) = 0.02, ε_r = 4.3) with the thickness of 1.6 mm, and it was excited by coaxial feed joined with microstrip line through via. The proposed antenna exhibited the bandwidth of 110.28% from 1.2 GHz to 4.15 GHz for |S₁₁|. Surface current distribution and radiation pattern at resonating frequencies 1.71, 2.28, 3.03 and 3.84 GHz were analyzed. Evolution of the antenna and effect of parameters were also studied to know the behavior of the antenna.

In this paper, a novel M-shaped UWB Vivaldi array antenna is presented. First of all, a simple M-shaped UWB Vivaldi antenna is designed, and its properties of return loss, radiation pattern, VSWR, gain, etc. are analyzed. An array of M-shaped UWB antenna is simulated and designed after the successful implementation of the simple UWB Vivaldi antenna. The designed antenna has operating frequency from 3.25 GHz to 8.85 GHz covering 5.6 GHz bandwidth. The antenna has flat gain over entire frequency range. The proposed antenna is fabricated on a commercially available FR-4 substrate having relative permittivity of 4.4 and height of 1 mm. The proposed antenna has wide band and good flat gain over entire frequency range. The proposed antenna can be used in next generation wireless communication because of its efficiency, gain and wide bandwidth.

We investigate thermal noise mechanisms and present analytical expressions of the noise power spectral density at high frequencies (HF) in Silicon-on-insulator (SOI) MOSFETs. The developed HF noise model of RF T-gate body contact (TB) SOI MOSFET for 0.13-μm SOI CMOS technology accounts for the mechanisms of 1) channel thermal noise; 2) induced gate noise; 3) substrate resistance noise and 4) gate resistance thermal noise. The extraction method of modeling parameter utilized by Y-parameter analysis on the proposed small-signal equivalent circuit is demonstrated in this paper. Excellent agreement between simulated and measured noise data is obtained at different temperatures.

Artificial magnetic conductor (AMC) is a periodic structure with in-phase reflection, which can be used in dual-polarization dipole antenna to reduce profile height. In this study, a low-profile dual-polarized dipole antenna with an AMC reflector is proposed by improving the AMC structure. The antenna consists of a pair of orthogonal planar dipoles with U-shaped slots, two T-shaped feeding lines, and an AMC reflector. The overall height is 0.132λ_{2.2 GHz}. Experimental results show that the proposed antenna has a wider bandwidth than other antennas of the same type. The impedance bandwidth of this antenna is 52.3% (1.65 GHz to 2.81 GHz), and the proposed antenna also has the advantages of low profile, high port isolation (<-30 dB), and low cross polarization (<-27 dB). These features can meet the current needs of the telecommunications industry.

In this communication, a dual-sense dual-polarized hybrid rectangular dielectric resonator antenna (RDRA) is explored. Two leading aims of the present article include: (i) to obtain dual-polarization characteristics i.e. the combination of linear and circular polarizations; (ii) to achieve quad-band features by using the concept of hybrid antenna. Modified printed line is used to excite dual radiating modes in RDRA i.e. TE^x_δ11 and TE^y_1δ1. In order to authenticate the proposed radiator, archetype of the proposed antenna is fabricated and tested. Good accord is established between measured and simulated outcomes. The proposed radiator is operated over four different frequency bands i.e. 1.81 GHz-2.06 GHz, 2.37 GHz --2.7 GHz, 3.35 GHz -- 4.4 GHz, and 4.62 GHz -- 5.62 GHz. Left Hand Circularly Polarized (LHCP) and Right Hand Circularly Polarized (RHCP) waves are obtained form 4.1-4.39 GHz and 4.78-5.2 GHz respectively. All these properties of the proposed radiator make it appropriate for 3G/WLAN/WiMAX applications.

The paper presents the application of a hybrid neuro-fuzzy model for the analysis and synthesis of a square multiband Sierpinski carpet fractal antenna. For the analysis model, the antenna geometrical parameters were taken as the input, and the resonant frequencies were obtained as the output while for the synthesis model, the resonant frequencies were taken as the input, and geometrical parameters were obtained as the output. Also, a model was trained to obtain the return loss characteristics for the given set of geometrical parameters. The developed model was validated by comparing the resonant frequencies and radiation patterns of the simulated and fabricated antennas.

Grounding grid is responsible for driving lightning and short circuit currents into ground. Faults in substation grounding grid can lead to significant rise in surface potential and ultimately loss to power system and operators. This paper proposes a novel technique based on derivative method to diagnose breakpoints in grounding grid. Derivative of surface magnetic flux density on circle results in peak at conductor's location. Once a conductor is broken the flow of current and surface magnetic field ceases, which is recognized by the absence of peak at corresponding conductor's location. The use of circle even enables this method for diagnosing diagonal branch. Furthermore, the method is analyzed for soil of different resistivities and monolayer and multilayer soils. Simulation results show that the proposed method is feasible for breakpoint diagnosis of grounding grid without excavation.

A highly efficient Doherty power amplifier (DPA) using shunted reactive load is designed to achieve wideband operation. For enhanced back-off efficiency over the whole bandwidth, a modified load modulation network (LMN), which employs a shunted reactive load at the combining point, was firstly designed to enlarge the effective load impedance of the carrier amplifier at low and high frequencies. Then, the two-point matching approach was employed to design the carrier and peaking output matching networks, which can eliminate the use of offset lines and simplify the LMN. Measurement results show that the designed DPA can deliver an efficiency of 48%-61% at 6 dB back-off power over the frequency band of 2.2-2.9 GHz. For a 20 MHz LTE modulated signal, an average efficiency of higher than 55% can be achieved at an average output power of 37 dBm, while the adjacent channel leakage ratio is below -49 dBc after linearization.

A broadband circularly polarized cross-shaped slot antenna with a parasitic cross-shaped patch and an improved feedline is proposed for wireless applications between 3-6 GHz. In order to achieve a wide axial ratio bandwidth that is totally enclosed within a wide impedance bandwidth, a wide cross slot in the ground plane and an L-shaped strip attached to the lower section of the feedline are employed. This design presents a technique for achieving an axial ratio (AR) bandwidth for a single fed antenna that is wider than most of the single fed slot antennas that currently exist. The proposed antenna with a compact size of 30 mm × 30 mm × 1.6 mm is fabricated and measured. A measured broadside 3 dB axial ratio bandwidth of 68.7% (3.1-6.35 GHz) within a measured impedance bandwidth of 84.1% (2.61-6.4 GHz) for S₁₁ < -10 dB is obtained. A measured peak gain of 3.8 dBi is obtained within the axial ratio bandwidth. The obtained results show that the antenna can be used for wireless devices that operate in the 3.3-3.8 GHz and 5.15-5.35/5.725-5.825 GHz (specified by IEEE 802.11a) bands for wireless standard technologies.

A novel rat-race coupler with wide adjustable range of power-dividing ratio and uncrossed input/output ports is presented by using coupling adjustable trans-directional (TRD) coupled lines, parallel coupled lines and a 180° phase shifting line. Wide adjustable range of power-dividing ratios is accomplished by varying the coupling of the TRD coupled lines. Moreover, with the combination of the TRD coupled lines and parallel coupled lines, the input and output ports of the rat-race coupler are uncrossed. The structure of the proposed rat-race coupler is analyzed, and the design equations are derived. As an example to validate the feature of the proposed rat-race coupler, a prototype operating at 1.6 GHz is devised, fabricated and measured. The measured results show that the designed coupler has a wide adjustable range (-7 ~ 15 dB) of power dividing ratio with a controlled voltage range of 3.5 to 13.5 V. 