Based on the altitude-dependent model of ITU-R slant atmospheric turbulence structure constant, the log-amplitude variance of laser beam propagation on the slant path through turbulent atmosphere is obtained with transmitter and receiver parameters and can be degenerated to the result of the horizontal path with atmospheric structure constant as a fixed value. These expressions are convenient tools for beam-wave analysis. Finally, we apply the ITU-R turbulence structure constant model to calculate collimated, divergent and convergent beam log-amplitude variance. The numerical conclusions indicate the log-amplitude variance of laser beam propagation on slant path is generally smaller than those on horizontal path.

This study investigates the effects of incorporating Doppler velocity measurements directly into track association and maintenance parts for single and multiple target tracking unit in a multi function phased array radar (MFPAR). Since Doppler velocity is the major discriminant of clutter from a desired target, the measurement set has been expanded from range, azimuth and elevation angles to include Doppler velocity measurements. We have developed data association and maintenance part of a well known tracking method, Interacting Multiple Model Probabilistic Data Association Filter (IMMPDAF), with the Doppler velocity measurements and demonstrated the performance improvement through simulations in terms of track update interval, track maintenance rate, RMS position estimation error, probability of detection and processing time. Since Doppler velocity measurements are employed in track maintenance, non-linear filters are used in the scheme leading to the use of Extended Kalman Filter (EKF) based PDAF. Comprehensive simulations have revealed that using Doppler velocity measurements along with 3D position measurements in heavy clutter conditions lead to an increase in track maintenance rate, track update interval; a decrease in position estimation error, processing time and no considerable effect on the probability of detection. This result is very significant for the efficient use of the limited resources of a multi function phased array radar.

A fast inhomogeneous plane wave algorithm is developed for the electromagnetic scattering problem from the composite bodies of revolution (BOR). Poggio-Miller-Chang Harrington-Wu (PMCHW) approach is used for the homogeneous dielectric objects, while the electric field integral equation (EFIE) is used for the perfect electric conducting objects. The aggregation and disaggregation factors can be expressed analytically by using the Weyl identity. Compared with the traditional method of moments (MoM), both the memory requirement and CPU time, are reduced for large-scale composite BOR problems. Numerical results are given to demonstrate the validity and the efficiency of the proposed method.

We propose single metal layer metamaterial bandpass filters based on compact complementary u-shaped resonators. Previously, metamaterial bandpass filters could only be achieved if a second conducting layer was utilized. Here, we propose a resonator concept that can directly be integrated with a single sided coplanar waveguide, enabling low fabrication costs and simple system integration. Furthermore, already a single unit cell yields a pronounced bandpass behavior without the need for cascading multiple resonators. Both, measurements and numerical simulations are presented. Using RO3003 as substrate, a low insertion loss of 1.71 dB and a corresponding 3-dB bandwidth ratio of 3.1% is achieved.

In this paper we study the optimization process of a novel hybrid antenna, formed by a Planar Inverted-F Antenna (PIFA) and a coplanar patch in the same structure, and intended to be used in mobile communications and WIFI applications simultaneously. This hybrid device has been recently proposed and characterized in the literature, and it has been shown that it allows a bandwidth of 850 MHz (49%) in the lower band and 630 MHz (11.25%) in the upper band. In spite of these good performance results, the fine tuning of the joint PIFA-patch parameters in the hybrid antenna is a hard task, not easy to automatize. In this paper we propose the use of an Evolutionary Programming (EP) approach, an algorithm of the Evolutionary Computation family, which has been shown to be very effective in continuous optimization problems. We use a real encoding of the antenna's parameters and the CST Microwave Studio simulator to obtain the performance of the antenna. The simulator is therefore incorporated to the EP algorithm as a part of the antenna's evaluation process. We will show that the EP is able to obtain very good sets of parameters in terms of the designer necessities, usually a larger bandwidth at the design frequencies. In this case, the bandwidth of the EP optimized antenna results in 980 MHz (55%) for the lower band and 870 MHz (17%) for the upper band.

Scanning a planar array in the x-z plane directs the beam peak to any direction off the broadside along the same plane. Reduction of sidelobe level in concentric ring array of isotropic antennas scanned in the x-z plane result in a wide first null beamwidth (FNBW). In this paper, the authors propose pattern synthesis methods to reduce the sidelobe levels with fixed FNBW by making the scanned array thinned based on two different global optimization algorithms, namely Gravitational Search Algorithm (GSA) and modified Particle Swarm Optimization (PSO) algorithm. The thinning percentage of the array is kept more than 45 percent and the first null beamwidth (FNBW) is kept equal to or less than that of a fully populated, uniformly excited and 0.5 λ spaced concentric circular ring array of same scanning angle and same number of elements and rings.

A fiber laser with 180 GHz ultrabroad linewidth is developed using a broadband light source and a bandpass filter. Active phase locking of two fiber amplifiers with 180 GHz linewidth is successfully realized using stochastic parallel gradient descent technique. The fringe contrast of the interference pattern is as high as 65% when active phase control is implemented. The reported results indicate a promising power scalability of fiber amplifier modules developed for phase locking.

We analyzed the microwave emission from a rough soil surface with exponential correlation by characterizing its dependences of polarization, look angle, and frequency. Using the same set of physical surface parameters of rms height and correlation lengths, results are obtained for a wide range of frequencies at 1.4 GHz, 5 GHz, 10 GHz, 18 GHz, and 36.5 GHz. Accurate simulations for the 2-D scattering problem are conducted by Galerkin's method with the rooftop basis function, followed by near-field integration, fine discretization, and cubic spline interpolation of surfaces. The multilevel UV method was employed to accelerate the solution. Accuracy is ensured by energy conservation check. Simulation results are compared with SPM, KA and AIEM. Results suggest that there exists distinct emission characteristic between the exponential and the Gaussian correlated surface. These charcateristics should be very useful in developing retrieval algorithm of the soil moisture from emissivity measurements.

The synthesis of optimal narrow beam low sidelobe linear array is addressed. Only the length of the array is constrained. The number, the positions and the weightings of the elements are left free. It is proven, that the optimal design is always an array with a small number of elements. One first demonstrates that among equally spaced linear arrays of given length, the sparsest Dolph-Chebyshev design, i.e., the one with the largest admissible inter-element distance, is the optimal one. Then, the restriction to equally spaced elements is removed, and the general problem is solved and discussed. It is shown that the sparsest Dolph-Chebyshev designs are optimal for array lengths in given specified intervals and close to optimal for all other lengths.

In this paper, a compact stepped-impedance hairpin resonator (SIHR) low-pass filter (LPF) with an improved split-ring resonator defected ground structure (ISRR DGS) and two elliptical DGSs is presented. The proposed LPF exhibits the advantages of low insertion loss, sharp cutoff characteristic, wide stopband over the ordinary LPFs. The introduced DGSs are presented to improve the in-band and out-band characteristic. An equivalent RLC circuit model of the two kinds of DGSs is presented and analyzed. Combining with these two structures, a new SIHR LPF having 3-dB cutoff frequency of 2.5 GHz is fabricated and measured. Measured results show that the selectivity of the proposed LPF is more than 100 dB/GHz and the insertion loss is less than 0.5 dB in the passband. A wide stop-band bandwidth with 20 dB attenuation from 2.58 up to 7.5 GHz is achieved. Moreover, the occupied area is only 20×25 mm².

In this paper, a novel compact wideband bandpass filter (BPF) is proposed using quadruple-mode resonator formed by attaching a short-circuited stub at the center plane and two identical impedance-stepped open stubs to high impedance microstrip line. The resonator can generate two even-modes f_m1, f_m3 and two odd-modes f_m2, f_m4 in the desired band. The even-mode resonant frequencies can be flexibly controlled by the short-circuited stub, whereas the odd-mode ones are fixed. When the open stubs are attached to the center plane nearby, they can be mainly applied to adjust f_m3, f_m4 into desired passband as the high odd-mode and even-mode resonant frequencies are vulnerable to their electronic lengths. Two transmission zeros near the lower and upper cut-off frequencies are separately created by the short-circuited stub and interdigital feeding lines, leading to a high rejection skirt. A wideband BPF with the fractional bandwidth 64% is simulated, fabricated and measured. The measured results agree well with the EM simulations.

A novel design of a compact dual inverted C-shaped slots antenna for dual-band (IEEE 802.11b/g, 2.4-2.484 GHz and IEEE 802.11a, 5.15-5.35/5.725-5.825 GHz) WLAN applications is proposed in this paper. The antenna is based on dual inverted C-shaped slots and a μ-shaped feeding structure. These fundamental configurations are applied to achieve two operating bands with resonating frequencies at about 2.45 GHz and 5.5 GHz to cover the dual WLAN bands. The proposed antenna is fabricated and tested. The simulated and measured results show that the slot antenna obtains two independent operation bands of 2.4-2.515 GHz and 5.14-5.85 GHz for S₁₁≤-10 dB, and also stable gain characteristic with peak gain variations less than 1 dBi for both the bands. Details of the analysis and research progresses are shown in the following sections to illustrate the design steps and the performance of the proposed antenna.

Packaging of planar MMICs poses a unique challenge at microwave frequencies as the dimensions of the encapsulating cavity are comparable to wavelength at the operational frequencies. In addition, the effect of ground loops (caused by bond wires exposed to ground over extended length due to gaps between interconnects) deteriorates the situation even further in circuits like MMIC switches requiring high isolation between ports. The ground loops cause reflections thereby deteriorating the insertion loss figure of merit. This paper presents optimization of design of a metal ceramic package used for packaging an SPDT MMIC switch working in the frequency range of 5-6 GHz. The microwave performance of the package was simulated using EM simulation with parameters including cavity dimensions, port placement, gaps between interconnect lines, package feed-thrus and MMIC chip pads. Detailed characterization of the bare package and packaged SPDT MMIC done later shows a good match between the simulated and measured performance. The SPDT MMIC performance degradation was arrested by improvement in the package structure and it showed insertion loss of -1.6dB and input/output (I/O) return losses of ~16dB in the new package as compared to the values of -2.1dB insertion loss and -12dB I/O return losses in the original package. The port-to-port isolation remained unchanged (~40 dB in both cases) as it is governed by the MMIC assembly inside the package rather than the conditions at the I/O interfaces in this kind of large sized packages.

This paper presents the design procedure and implementation of an innovative compact bandpass filter in UHF band by using Composite Right/Left Handed Transmission Line (CRLH-TL) by using parasitic effects of these structures. The CRLH-TL is utilized in order to minimize the overall size of component and reject higher ordered harmonics. The metamaterial transmission line is about one-eighth of a wavelength long and acts as both resonator and inverter which provide capacitive coupling between neighboring sections. To show the validity of design procedure, two prototype bandpass filters were fabricated and tested. We have shown that very good agreement exists between simulation results and those obtained by measurement.

A simple design of one dimensional gradual stacked photonic crystal (GSPC) structure has been proposed. The proposed structure consists of a periodic array of alternate layers of SiO2 and Si as the materials of low and high refractive indices respectively. The structure considered here has three stacks of periodic structures with five layers each. The lattice period of successive stack is increased by a certain multiple (say gradual constant, γ) of the lattice period of the just preceding stack. For numerical computation, the method of transfer matrix method (TMM) has been employed. It is found that such a structure has wider reflection bands in comparison to a conventional dielectric PC structure, and the width of the omni-directional reflection (ODR) bands can be enlarged by increasing the value of the gradual constant. Hence, a GSPC structure can be used as a broadband omnidirectional reflector, and the bandwidth of omni-directional gaps can be tuned to a desired wavelength region by choosing appropriate value of γ.

The objective of this paper is to analyze the behavior of specular scattering for different soil texture fields at various soil moisture (m_v) and analyze the data to retrieve the soil moisture with minimizing the effect of the soil texture. To study the soil texture effect on specular scattering 10 different soil fields were prepared on the basis of change in soil constituents (i.e, percentage of sand, silt and clay) and experiments were performed in both like polarizations (i.e., HH-polarization and VV-polarization) at various incidence angles (i.e., varying incidence angle from 25°to 70°in step of 5°). Angular response of specular scattering coefficients (σ°_hh in HH-polarization and σ°_vv VV-polarization) were analyzed for different soil texture fields with varying soil moisture content whereas the surface roughness condition for all the observations were kept constant. The changes in specular scattering coefficient values were observed with the change in soil texture fields with moisture for both like polarizations. Further, copolarization ratio (P=(σ°_hh/σ°_vv) study was performed and it was observed that the dependency of copolarization ratio for change in soil texture field at constant soil moisture is less prominent whereas the value of copolarization ratio is varying with variation of moisture content. This emphasizes that copolarization ratio may be minimizing the effect of soil texture while observing the soil moisture on specular direction. Regression analysis is carried out to select the best suitable incidence angle for observing the moisture and texture at C-band in specular direction and 60°incidence angle was found the best suitable incidence angle. An empirical relationship between P and m_v was developed for the retrieval of m_v and the obtained relationship gives a good agreement with observed m_v. In addition, m_v was also retrieved through the Kirchhoff Approximation (SA) and a comparison was made with the retrieved results of empirical relationship. The empirical relationship outperformed the SA.

This paper presents an exact analytical method for the computation of the magnetic field distribution in surface-mounted permanent-magnet (PM) motors for any pole and slot combinations including fractional slot machines. The proposed model takes into account the slotting effect and the armature reaction magnetic field. The analytical method is based on the resolution of the two-dimensional Laplace's and Poisson's equations in polar coordinates (by the separation of variables technique) for each subdomain, i.e., magnet, airgap and slots. Magnetic field distributions, back electromotive force and electromagnetic torque (cogging torque and load torque) computed with the proposed analytical method are verified with those obtained from finite element analyses.

In this paper, a planar monopole antenna for Ultra-Wideband (UWB) communications with a notched behavior in the two sub-bands UNII1 and UNII2 of the Wireless Local Area Network (WLAN) band is presented. The antenna geometry is described by means of a spline curve and a rectangular slot. Numerical and experimental results are reported to assess the effectiveness of the proposed design in terms of impedance matching and radiation characteristics.

A new reflectarray configuration is proposed for low-loss applications at millimeter waves. It is based on the use of dielectric resonator antennas (DRA) as radiating unit-cells. The phase response of the elementary cell is controlled by adjusting the length of a parasitic narrow metal strip printed on the top of each DRA. A 330° phase dynamic range is obtained for DRAs made in rigid thermosetting plastic (ε_r=10). As the antenna radiating aperture is non flat, an original low-cost fabrication process is also introduced in order to fabricate the parasitic strips on the DRA surface. A 24×24-element array radiating at broadside has been designed at 30 GHz and characterized between 29 and 31 GHz. The antenna gain reaches 28.3 dBi at 31 GHz, and the measured -1 dB-gain radiation bandwidth is 5.2%. The 3.2 dB loss observed between the measured gain and theoretical directivity is mainly due to the spillover loss (2.3 dB). The total dielectric and conductor loss is less than 0.9 dB.

In recent years, location determination systems have gained a high importance due to its rule in the context aware systems. In this paper, we will design a multi-floor indoor positioning system based on Bayesian Graphical Models (BGM). Graphical models have a great flexibility on visualizing the relationships between random variables. Rather of using one sampling technique, we are going to use multiple sets each set contains a collection of sampling techniques, the accuracy of each set will be compared with each other.