A novel microstrip array antenna based on the meta-material zeroth-order resonator (ZOR) is presented in this paper. Considering both zeroth-order resonance and the array theory, a resonant array antenna has been designed and fabricated which has small dimensions both in length and width as well as an acceptable gain. Since the resonant frequency of the zeroth-order resonator is independent of the physical length of the resonator and determined only by LC values loaded in the resonator, therefore, antenna size can be reduced arbitrarily with no changes in the operation frequency and due to the array structure antenna gain can be enhanced. Additional benefit of the ZOR antennas is lower ohmic losses as compared to the other small antennas and hence the efficiency of the antenna is higher. The discrepancy between simulation and measurement determined by fabricating some of the simulated design and comparison between the results, has been taken into account for designing the final array. A small-sized two-elements ZOR array antenna with 50% reduction in size as compared to the conventional array with a acceptable gain and broad radiation pattern is tested at 4.25 GHz. The proposed antenna has application in radio altimeters. The commercial softwares such as CST and HFSS were utilized for design and analysis of the structure.

In this paper, two compact patch antenna designs for a new application --- outdoor RF energy harvesting in powering a wireless soil sensor network --- are presented. The first design is a low-profile folded shorted patch antenna (FSPA), with a small ground plane and wide impedance bandwidth. The second design is a novel FSPA structure with four pairs of slot embedded into its ground plane. Performance of both antennas was first simulated using CST Microwave Studio. Antenna prototypes were then fabricated and tested in the anechoic chamber and in their actual operating environment --- an outdoor field. It was found that the FSPA with slotted ground plane achieved a comparable impedance bandwidth to the first design, with an overall size reduction of 29%. Simulations were also carried out to investigate the effects of different design parameters on the performance of the proposed slotted ground plane FSPA.

We will demonstrate an alternative topology to greatly increase the operating bandwidth of an analog RF feedback power amplifier. A limited operating bandwidth due to the group delay mismatch of a feedback loop discouraged the use of an RF feedback technique in spite of its powerful linearization performance and great tolerance capability. By introducing a negative group delay circuit (NGDC) in the feedback loop, group delay match condition could be satisfied. With the fabricated 2-stage distributed element negative group delay circuit with a 30MHz of bandwidth and a -9 ns of group delay for a wideband code division multiple access (WCDMA) downlink band, the proposed feedback amplifier with the proposed topology experimentally achieved an adjacent channel leakage ratio of -53.2 dBc with a cancellation bandwidth of over 50 MHz.

Antenna design problems often require the optimization of several conflicting objectives such as gain maximization, sidelobe level (SLL) reduction and input impedance matching. Multi-objective Evolutionary Algorithms (MOEAs) are suitable optimization techniques for solving such problems. An efficient algorithm is Generalized Differential Evolution (GDE3), which is a multi-objective extension of Differential Evolution (DE). The GDE3 algorithm can be applied to global optimization of any engineering problem with an arbitrary number of objective and constraint functions. Another popular MOEA is Nondominated Sorting Genetic Algorithm-II (NSGA-II). Both GDE3 and NSGA-II are applied to Yagi-Uda antenna design under specified constraints. The numerical solver used for antenna parameters calculations is SuperNEC, an object-oriented version of the numerical electromagnetic code (NEC-2). Three different Yagi-Uda antenna designs are considered and optimized. Pareto fronts are produced for both algorithms. The results indicate the advantages of this approach and the applicability of this design method.

This paper estimates separately the components of scattering waves generated in cylinder-body model for body area networks. For the evaluation, scattering field formulations in relation to uniform cylinder- and slab-body models are provided, and the reliability of the analyses is testified by the comparison with results computed by the finite-difference time-domain (FDTD) method. Creeping waves, cylinder leaky waves, and cylinder guided waves, which are created only in cylindrical structure, are extracted quantitatively by contrasting the scattering waves that are calculated with the two body models. In addition to the extracted waves, other components of scattering waves such as reflected waves, transmitted waves, surface waves, leaky waves, and guided waves also are examined. From evaluations with various operating frequencies and thicknesses of the body model, it is confirmed that reflected waves have the most influence on electrical characteristics of a source. Moreover creeping waves and cylinder leaky waves are generally dominant at the opposite side of the cylinder when a source is located near cylinder surface. Furthermore, the existence of creeping waves with low attenuation in the vicinity of cylinder surface is demonstrated by electric field intensities calculated by varying the observation point along cylinder axis.

An omnidirectional horizontally polarized antenna with improved gain is realized by using EBG cavity. The EBG cavity is composed of ring metallic strips etched on thin FR4 substrate and two metallic reflectors installed on up/down sides, which is designed to have a low effective index of refraction (n<1). The metallic strips are arranged in concave shape. Compared with the antenna without EBG cavity, the EBG cavity makes the vertical beam become narrow and effectively improves the omnidirectional antenna gain. An experimental prototype is fabricated to validate the proposed analysis. Measured data show the gain of the antenna with the EBG cavity improved by about 2.72 dBi at 5.7 GHz, and the measured data have a good agreement with numerical results.

A new composite power plane using spiral electromagnetic bandgap (EBG) and external magnetic material is proposed for simultaneous switching noise (SSN) suppression in mixed-signal systems. The proposed power plane has an external magnetic material partially placed on the top of perforated spiral-bridged EBG plane. The EBG bandgap is shifted to lower frequencies by the real part of the permeability (μ_r') and the power plane Q-factor is decreased by the imaginary part of the permeability (μ_r") associated with the magnetic loss. 30 dB suppression of the SSN propagation has been measured from 190 MHz to 1 GHz by virtue of the complex permeability. The proposed EBG power plane is expected to reduce the circuit size and to improve the power integrity of the mixed-signal systems.

In this paper, a new compact dual-polarized microstrip patch antenna is proposed. The patch is of rectangular shape and fed by a gap between the patch edge and a microstrip open end. Gap feeding at the edge of a rectangular patch antenna is proposed for the first time in this paper. This method of feeding occupies a negligible space compared to other feeding methods such as a quarter-wave transformer feeder, an inset feeder, a proximity coupler, and an aperture-coupled feeder. Dual-polarized radiation is realized by feeding a rectangular patch with two orthogonal gaps. First, a single-polarized patch is designed. The impedance matching property of the gap is analyzed using an equivalent circuit. Next, starting from dimensions of the single-polarized patch, a dual-polarized patch antenna is designed by optimizing the patch length and gap width. The designed antenna is fabricated and tested. The fabricated antenna has reflection coefficient less than -10 dB, port isolation greater than 30 dB, over 14.5-15.2 GHz, and a gain of 6.2 dBi at 14.9 GHz.

By using field expansion in terms of the Legendre polynomials and Schelkunoff functions, Maxwell's equations in the spherical coordinate system are cast into a matrix form which lends itself to the analysis of a multilayer conical waveguide. The matrix formulation is then used to obtain an eigen-value problem whose eigen-values are the allowable wave-numbers for propagation in the radial direction. To verify the proposed numerical approach, it is used to evaluate the resonance frequency of a partially filled spherical resonator. The computed resonance frequencies are then compared with those obtained using commercial software based on the finite-element method. The computation time is enormously reduced using the semianalytical method of this work. Although results are shown for lossless isotropic dielectrics, the method is also applicable to conical waveguides made of lossy dielectrics even with negative permittivity.

We propose a kind of novel photonic crystal fibers (PCFs) based on a fiber core with arrays of subwavelength circular air holes, achieving the flexible control of the birefringence or the dispersion property of the PCFs. A highly birefringent (HB) PCF is achieved by employing arrays of subwavelength circular air hole pairs in the fiber core, which are arranged as a conventional hexagonal lattice structure with a subwavelength lattice constant. The HB-PCF is with uniform and ultrahigh birefringence (up to the order of 0.01) in a wavelength region from 1.25 μm to 1.75 μm or even a larger region, which, to the best of our knowledge, is the best birefringence property of the PCFs. A dispersion-flattened (DF) PCF with near-zero dispersion is achieved by employing arrays of subwavelength circular air holes in the fiber core arranged as a conventional hexagonal lattice structure with a subwavelength lattice constant, which contributes negative waveguide dispersion to the PCF. The proposed design of the DF-PCF provides an alternate approach for the dispersion control of the PCF. Besides the high birefringence and the flattened near-zero dispersion, the proposed PCFs with a fiber core of arrays of subwavelength circular air holes have the potential to achieve a large mode area single mode PCF.

A initial-boundary value problem for the system of Maxwell's equations with time derivative is formulated and solved rigorously for transient modes in a hollow waveguide. It is supposed that the latter has perfectly conducting surface. Cross section, S, is bounded by a closed singly-connected contour of arbitrary but smooth enough shape. Hence, the TE and TM modes are under study. Every modal field is a product of a vector function of transverse coordinates and a scalar amplitude dependent on time, t, and axial coordinate, z. It has been established that the study comes down to, eventually, solving two autonomous problems. i) A modal basis problem. Final result of this step is de…nition of complete (in Hilbert space, L₂) set of functions dependent on transverse coordinates which originates a basis. ii) A modal amplitude problem. The amplitudes are generated by the solutions to Klein-Gordon equation (KGE), derived from Maxwell's equations directly, with t and z as independent variables. The solutions to KGE are invariant under relativistic Lorentz transforms and subjected to the causality principle. Special attention is paid to various ways that lead to analytical solutions to KGE. As an example, one case (among eleven others) is considered in detail. The modal amplitudes are found out explicitly and expressed via products of Airy functions with arguments dependent on t and z.

A novel tri-band monopole antenna applied to WLAN / WiMAX applications is proposed in this paper. The antenna comprises of two semicircles: one is fed by a microstrip line, and the other is shorted to the ground. By incorporating L-shaped strips, good filter as tri-band performance is achieved. The proposed antenna shows a good multi-band property to satisfy the requirement of WLAN in the 2.4/5.2/5.8 GHz bands and WiMAX in the 2.5/3.5/5.5 GHz bands. In addition, a near omni-directional radiation characteristic is also obtained. Experimental data show that the antenna can provide three separate impedance bandwidths of 400 MHz (centered at 2.6 GHz), 400 MHz (centered at 3.4 GHz) and 1100 MHz (centered at 5.3 GHz) with two fine notched bands at the undesired bandwidths.

Statistical characteristics of scattered electromagnetic waves by turbulent magnetized plasma slab with electron density and magnetic field fluctuations are considered via the perturbation method and boundary conditions. Magnetic field fluctuates both in magnitude and direction. Analytical expressions for the component of scattered electric field, correlation functions of the amplitude and phase fluctuations, and also the phase structure function for arbitrary correlation functions of fluctuating plasma parameters are derived. The obtained results are valid for near and far zones. Under equal conditions, at strong magnetic fields, electron density fluctuations play the important role and in this case the imposed magnetic field decreases fluctuation intensity of the ordinary and extraordinary waves. Numerical calculations of statistical characteristics of scattered radiation were carried out for anisotropic Gaussian correlation function for electron density fluctuation and correlation tensor of the second order for the fluctuation of an external magnetic field. The phase portraits of correlation functions of the amplitude and phase fluctuations are constructed.

Study of a novel design of dual-band folded antenna with an L-shaped slot on the ground plane has been proposed for wireless local area network (WLAN) applications. The proposed antenna occupies a low profile above the ground plane. This characteristic makes it suitable for laptop PC applications. The proposed antenna can provide two impedance bands at 2.4 and 5.2/5.8 GHz, which satisfies WLAN applications. Details of the proposed antenna design and measured results are presented and discussed.

Infinite reflectarrays in the X-band frequency range has been designed, and various slot configurations have been proposed to optimize the design of reconfigurable reflectarray antennas in the X-band frequency range. It has been demonstrated that the introduction of slots in the patch element causes a decrease in the maximum surface current density (J) and electric field intensity (E) and hence causes a variation in the resonance frequency of the reflectarray. Waveguide simulator technique has been used to represent infinite reflectarrays with a two patch unit cell element. Scattering parameter measurements of infinite reflectarrays have been carried out using vector network analyzer and a change in resonant frequency from 10 GHz to 8.3 GHz has been shown for a slot width of 0.5W (W is the width of patch element) as compared to patch element without slot. Furthermore a maximum attainable dynamic phase range of 314°has been achieved by using slots in the patch element constructed on 0.508 mm thick substrate with a maximum surface current density (J) of 113A/m and Electrical field intensity (E) of 14 kV/m for 0.5W slot in the patch element.

This paper proposes asymmetrical step-impedance resonators bandpass filters (ASIRs) for suppressing a wide stopband, ensuing in size reduction and ease of fabrication. The filters have been designed at the operating frequency around 2.0 GHz using half- and quarter-wavelength asymmetrical step-impedance resonators. The concept of existent odd- and even-mode characteristics is used to approve the proposed filter structure. The filter can not only suppress the unwanted signals more than 10 f₀, but also produce low passband insertion loss and high return loss. A good agreement is obtained between the simulation and measurement results.

In this paper, the ICA (independent component analysis) technique is applied to PCA (principal component analysis) based radar target recognition. The goal is to identify the similarity between the unknown and known targets. The RCS (radar cross section) signals are collected and then processed to serve as the features for target recognition. Initially, the RCS data from targets are collected by angular-diversity technique, i.e., are observed in directions of different elevation and azimuth angles. These RCS data are first processed by the PCA technique to reduce noise, and then further processed by the ICA technique for reliable discrimination. Finally, the identification of targets will be performed by comparing features in the ICA space. The noise effects are also taken into consideration in this study. Simulation results show that the recognition scheme with ICA processing has better ability to discriminate features and to tolerate noises than those without ICA processing. The ICA technique is inherently an approach of high-order statistics and can extract much important information about radar target recognition. This property will make the proposed recognition scheme accurate and reliable. This study will be helpful to many applications of radar target recognition.

In order to enhance the accuracy of the complex permittivity data employed in Ground Penetrating Radar (GPR) techniques, an adaptive cavity setup is presented. The use of moveable walls permits to relax the mechanical constraints on the sample dimensions so that it can be employed also in complicate measurement condition as, for example, in the case of wet samples. Moreover, exploiting the cavity resonance phenomenon, low loss materials, such as some type of marbles, can be accurately evaluated. The numerical characterization, the parametric analyses and the L-band measurement results show the validity and the reliability of this configuration.

In this paper, synthesis of superconducting circular antennas mounted on circular array is designed by the combination of a method based on particle swarm and full-wave method. Full-wave method is used for computing the resonant frequency, the bandwidth, radiation pattern and efficiency of a perfectly superconducting, or an imperfectly conducting circular microstrip, which is printed on isotropic or uniaxial anisotropic substrate. Particle Swarm Optimization (PSO) has been used to obtain the minimum side lobe level (SLL) of circular array, by varying element excitations and/or positions. Numerical results concerning the effect of the parameters of substrate and superconducting patch on the antenna performance are presented and discussed. It is found that superconducting circular antenna could give high efficiency. Also, results show the efficiency of PSO in producing desired radiation characteristics and are in good agreement with previously published data.

Radio astronomy has a wide electromagnetic spectrum. It is based on antennas, electronics, software etc., and thus highly technical. The radio data obtained from distant objects like stars, galaxies, pulsars etc. are useful for studying the Universe. Many of the radio emissions, especially from the Sun have been studied over decades for understanding the ionosphere and its effects on radio communication. Untill now, this subject of radio astronomy has found its existence among those who are associated with astronomy and possessing at least some knowledge of RF engineering. A requirement of a review literature on this subject with technical details is felt by many working engineers and scientists. It is thus proposed to write a series of articles covering the subject from both engineering and scientific angles. This paper is the first of this series. It focusses on the foundation of this subject and briefly describes the supersynthesis technique. Overview of various concepts like cosmic radio signals, continuum, synchrotron emission etc., general instrumentation for radio astronomy, imaging techniques and radio interference have have been presented.