A 3-bit phase array system including phase shifter blocks and antenna elements has been developed on a coplanar waveguide (CPW) using micro electromechanical system (MEMS) technology. The non Euclidean Koch fractal geometry has been used to improve the frequency behavior of the entire system. It is shown that the fractal geometry makes the design to have lower profile, wider frequency bandwidth, and lower mutual coupling effects. It also decreases the actuation voltage of the MEMS switch elements. The fabrication process has been fully described and the measured values regarding every single block is presented.

In implementing electromagnetic vulnerability (EMV) testing on operational helicopters fielding a variety of avionic, communication, and weapons systems, the testing levels as spelled out in MIL-STD-464A require most test labs to position the high power source antennas unreasonably close to the test item (sometimes within 2 m). Questions naturally arise concerning the efficacy of such testing with respect to both the manner of coupling of the fields to the helicopter systems as well as the levels required to achieve reasonable confidence in the coupling effects. This paper presents a comparison of the electric fields interior to an axially slotted circular cylinder and the fields in the slot aperture as a function of the distance from the source to the test item. Also, these measured interior and aperture fields are compared to two different mathematical/numerical models of the conducting cylinder with an axial slot running the length of the cylinder. Additional measurements are presented for the fields interior to a finite cylinder with conducting endcaps and a significantly reduced slot of finite length. Comparisons to one of the mathematical/numerical models for this finite length cylinder with finite length slot are presented also.

An efficient double superimposition model (DSM) is proposed to generate two-dimensional (2-D) ocean surface waves. On the basis of this efficient model, a modulated slope-deterministic facet model (MSDFM) is developed to compute the radar cross section (RCS) of synthetic aperture radar (SAR) for the generated ocean surface. Then, the properties of the SAR imaging mechanism for wind seas are discussed from a combination of SAR and ocean wave parameters. Furthermore, a hybrid facet scheme, which is the combination of physical theory of diffraction equivalent edge currents (PTDEEC) and physical optics (PO) method, is introduced to analyze the high frequency scattering characteristics of large ship target. Finally, this hybrid facet scheme combines with the four-path model and MSDFM to investigate SAR imaging for the composite model of ship on dynamic ocean scene. The resolution degradation of ship-ocean model arising from different facet velocities within a SAR resolution cell and the range migration caused by coupling scattering are investigated in this paper. SAR imagery simulations of marine scene are illustrated, proving the validity and practicability of the presented algorithms.

In this paper a square monopole antenna has been proposed which can be used for Ultra Wideband applications. Band-notch performance is introduced by an E-shaped slot on the patch. The dimensions are optimized to give not only the usual 3-10 GHz bandwidth with rejection in the 5-6 GHz band which is commonly used for WLAN, but also short received pulse duration when transmitted and received using a pair of these antennas. The demonstration of short received pulse-width is the primary novelty reported. The performance is verified by time domain measurements, in addition to the usual antenna characterization.

Research on digital modeling and realization of non-correlation measurement frame for compressive sensing (CS) is conducted aiming at applying CS to imaging radar. FPGA based Analogue-to-Information Converter (AIC) is proposed and implemented. Real measurement data from AIC hardware platform and simulation data from AIC software platform are compressed to get range profiles, and the results agree well with what expected. The results show that the noise and synchronization error in real system deteriorate the performance of AIC thus CS remarkably.

A new design of microwave band pass filter design is presented using metamaterial-inspired Epsilon Near Zero (ENZ) and Mu Near Zero (MNZ) behaviors. These filters are based on waveguide technology. The proposed structure allows us to reduce the number of tunnels normally used for passband filter design by reducing its size. It is also incorporated the half mode concept to the tunnels leading a greater miniaturization. Two Chebyshev filters with two and four-poles were designed, fabricated and measured showing good agreement between simulated and experimental results.

We investigate the localized surface plasmon resonances (LSPR) of a pair of dielectric-core/silver-shell nanospheres, with and without a silver nanobar connecting them, for different values of the permittivity of the dielectric core, using the finite element method. Results show that the structure of a pair of core shells with a nanobar possesses a distinct blue-shifted behavior that can be manipulated from near infrared to visible light. The near field intensity can be enhanced by several orders of magnitude and the working wavelengths depend on the shell thickness, dielectric medium in hollow metallic shell and the diameter of the nanobar. In addition, three or more pairs of nanospherical chain waveguides have also been investigated in our simulations.

To meet the requirements for broadband operation, high port-to-port isolation, and miniature chip area, a doubly balanced monolithic microwave ring mixer with an advanced IF extraction fabricated using 0.15 μm GaAs pHEMT process is presented. A miniature Marchand-like spiral balun with low-pass filter is used to extract IF signals and maintain balun performance simultaneously. The low-pass filter can filter out both the RF and LO signals. This miniaturized mixer design can mitigate layout complexity, improve port-to-port isolations suitable for ultra-broadband Ku-, K-, and Ka-band applications. Subsequently, the LO/RF-to-IF isolations are greater than 43.2 and 32 dB from 11 to 40 GHz, respectively. The LO-to-RF isolation is between 26.9 and 50.7 dB within the same swept range. The conversion loss is 7.2-12.4 dB within the operating bandwidth.

A planar array composed of 41 parasitic dipoles, above a ground plane, fed by an active dipole at 5 GHz, was designed to obtain a pencil beam pattern with a moderate gain and bandwidth. Experimental results are in good agreement with the theory and show a pattern with an 18.78 dB gain, a sidelobe level (SLL) of -15 dB, an impedance bandwidth of 16.53% (the frequency range over which the value of S11 is below -10 dB) and a 2.7% bandwidth that is achieved within 1 dB gain variations.

This paper presents a novel permanent-magnet (PM) machine for wind power generation. In order to achieve high power/torque density as well as get rid of the nuisances aroused by the mechanical gearbox, a coaxial magnetic gear (CMG) is engaged. Different from the existing integrated machine in which armature windings are deployed in the inner bore of the CMG as an individual part, stator windings are directly inserted among the slots between the ferromagnetic segments in this proposed machine. Thus, it can offer several merits, such as simpler mechanical structure, better utilization of PM materials and lower manufacturing cost. Moreover, by artfully designing the connection of the armature windings, the electromagnetic coupling between the windings and the outer rotor PMs can be dramatically decreased, and the electromechanical energy conversion can be achieved by the field interaction between the inner rotor PMs and the armature windings. This machine adopts an outer-rotor topology, for compact design, the wind blades are directly mounted on the outer rotor of the machine, while the fairing is equipped on the front end of the stator. The design details and operating principle are elaborated. By using the time-stepping finite element method (TSFEM), the electromagnetic characteristics of the proposed machine are analyzed. The results verify the validity of the proposed machine.

A novel kind of room temperature terahertz photodetector based on Electromagnetically Induced Transparency (EIT) is presented. The main idea for room temperature and THz range operation is reduction of dark current which is done by converting of the incoming terahertz signal (long-wavelength Infrared signal) to short-wavelength field through EIT phenomena. For realization of this idea, we examine EIT phenomena in multi levels atomic system and quantum wells cascade structures. In the proposed structure the quantum interference between long wavelength and short-wavelength radiation modifies the absorption characteristic of short-wavelength probe field. By this means, the terahertz signal does not interact directly with ground state electrons, but affects on the absorption characteristics of the short-wavelength or visible probe optical field which directly interact with ground state electrons. Therefore, the important thermionic dark current in terahertz detection, can be strongly reduced. So, the proposed idea is appropriate for terahertz and room temperature applications.

In this paper, for the very first time, a general algorithm for designing rectangular microstrip patch antenna, partially loaded with SNG (Single Negative) (MNG (µ Negative) and ENG (ε Negative)) metamaterial has been proposed to achieve better radiation performance. Then, applying our proposed algorithm, theoretically we have predicted novel dual band miniaturized rectangular patch antennas (loaded with MNG metamaterial) for two different bands using unconventional interface resonance mode under fundamental TM010 mode. Then we have proposed a complete design of magnetic inclusions, presenting full wave numerical simulations of the structure, which effectively supports the theoretical expected resonant modes as well as satisfactory radiation pattern performance. Prior to our current work, impossibility of sub-wavelength or electrically small rectangular patch antenna has been demonstrated using ENG metamaterial. However, in this paper, we have indicated a direction towards the real-life implementation of possible miniaturized rectangular patch antennas partially loaded with MNG metamaterial. The algorithm proposed in this paper is the key to choose the appropriate material parameter to design all such antennas.

This study investigates possible lightning threats to naval crafts, especially those sailing in the shallow waters of tropical oceans where thunderstorms prevail throughout the year and Far-East Asian region where dangerous positive lightning is a significant characteristic in winter thunderstorms. It is empathized that sea water acts as nearly a perfect conductor thus lightning electromagnetic transients propagate over the sea with almost zero attenuation of amplitude and high frequency components intact. The ratio between the peak electric fields at 5 km from the lightning channel, after fields propagate over dry soil and over sea water is 0.75. The ratio between the peak electric field derivatives under the same conditions is 0.1. Such small ratios are observed in the magnetic fields and their time derivatives as well. Apart from the conductivity, the topological irregularities of the plane over which propagation takes place also contribute to further attenuation of fields and their time derivatives. This makes marine naval systems more vulnerable to lightning induced effects than their ground-based counterparts. The paper discusses in detail the lapses of existing naval standards in the defense of electrical and electronic systems against both direct lightning currents and induced effects of nearby lightning. Consequently we propose the development of a dedicated standard for the lightning protection of naval systems, with the inclusion of several significant recommendations specified in this paper.

A multimode Brillouin Erbium Fiber Laser BEFL, at 1550 nm band, with in-cavity intensity modulation is demonstrated. The output of the laser is in the form of nanosecond pulses. The longitudinal mode separation is increased, which results in both reducing the number of oscillation modes and, at the same time, changing the output pulses repetition rate to be multiples of the round trip cavity frequency. It is also demonstrated that the number of modes is greatly reduced by the combination of active mode locking and the group velocity dispersion arising from the change in the refractive index at each mode due to the change in its gain within the Brillouin gain bandwidth. A case of a quasi single mode is reached where the output is nearly CW with very low sinusoidal modulation index.

This paper presents a high speed configurable FPGA-based wideband channel sounder with signal bandwidths up to 200 MHz and results of a study of dynamic urban picocell channel. The use of FPGA allows the sounder to be adaptable for measurements in different scenarios. Adaptable options include changes to the waveform, bandwidth, channel sampling rate and real-time averaging to improve signal-to-noise ratio in weak signal conditions. The implemented architecture has led to a 70% reduction in size and weight compared to sounders in use elsewhere making it ideal for mobile channel measurements. The study of an urban picocell channel has shown that dynamic variation due to automotive traffic introduces average signal strength fades of up to 5 dB but causes frequency selective fading with depths of up to 40 dB. Existing channel models assume antenna heights of more than 6 m and path lengths of more than 30 m. Therefore there is a need for shorter path models and this paper proposes a linear picocell channel model for static and dynamic urban environment.

Applying four-dimensional differential-form formalism, a novel class of electromagnetic media, labeled as that of P-media, is introduced in terms of a simple rule. It is shown that it is not possible to define the medium by expressing D and B in terms of E and H, whilst using 3D Gibbsian vectors and dyadics. Moreover, the basic properties of P-media are shown to be complementary to those of the previously known Q-media, which are defined in a somewhat similar manner. It is demonstrated that, for plane waves in a P-medium, there is no restriction to the wave one-form (corresponding to the k-vector). Importantly, the uniaxial P-medium half space also leads to another realization of the recently studied DB boundary conditions. Finally, a generalization of the class of P-media is brie y discussed. It is shown that the dispersion equation of a plane wave in the generalized Pmedium is decomposed into two conditions, each of which corresponds to a certain polarization condition. This occurrence resembles the behaviour of the generalized Q-medium.

We present an efficient way to generate the inverse synthetic aperture radar (ISAR) image of a target at an arbitrary aspect angle using the shooting and bouncing ray (SBR) method, which is much faster than the conventional approach by inverse Fourier transforming the computed scattered fields over frequency and aspect domain. We propose a general image-domain ray-tube integration formula, which contains aspect-dependent factors. The new formula can provide ISAR images of a target rapidly and conveniently in different image planes at different aspect angles in a world coordinate system. The ISAR images of a cube and an aircraft for several aspect angles and different image planes are presented to demonstrate the efficiency and accuracy of the general formula. The proposed method is more significant when large amount of ISAR images of a target are required to build the database for target recognition.

A novel compact square slot antenna design with coplanar waveguide (CPW)-fed for dual-band operation is presented. The proposed antenna is simply composed of a square slot resonator and a monopole radiator. By employing the special square slot structure, the antenna can achieve a new resonance while maintaining a small size. Based on this concept, a prototype of dual-band antenna is designed, fabricated and tested. The experimental results show the antenna has the impedance bandwidths of 400 MHz (2.33-2.73 GHz) and 1020 MHz (3.27-4.29 GHz), covering both WiMAX in the 2.5/3.5 GHz bands and WLAN in the 2.4 GHz band.

In this paper, a reflectarray antenna composed of a combination of double-petal loops of variable size is presented. To evaluate the performance of the designed element, a parametric study is carried out using Ansoft HFSS. For the optimal parametrics, the proposed structure shows an almost linear behavior, while the phase range is in excess of 500°. Then, a prime-focus 77-element reflectarray with this type of element has been designed and implemented. The measured results show that the obtained 1-dBi gain bandwidth of the reflectarray with double-petal loop elements can reach as large as 25% and the highest gain is about 19.3 dBi. Compared with the existing single layer elements (cross and rectangle loop, double rings, etc), microstrip reflectarray with this double-petal loop element can obtain a larger bandwidth.

The major objective of the study was to assess the safety of electric line workers exposed to of a double circuit 132 kV transmission line for different scenarios. The double circuit 132-kV, 60 Hz transmission line has a power rating of 293 MVA and a maximum recorded peak load current of 603 A. The charge simulation and the Biot Savart methods were used by EPRI workstation software to compute the external electric and magnetic fields around a 132 KV transmission line. We used the calculated external electric and magnetic field exposures to determine the induced electric field and induced current densities inside the human body. This was performed using the Finite Difference Time Difference computational algorithm in EMPIRE commercial software, with a 6 mm voxel resolution. We used the Visible Human (VH) to investigate the internal induced electric field and circulating current densities in more than 40 different tissues and organs of the VH. We found that the worker exposure levels to extremely low frequency electromagnetic fields are below the recommended IEEE international standards limits for the studied scenarios. In all scenarios the maximum induced current densities and electric fields were in the bone marrow of the feet.