For maneuvering target tracking, we propose a novel grey prediction based particle filter (GP-PF), which incorporates the grey prediction algorithm into the standard particle filter (SPF). The basic idea of the GP-PF is that new particles are sampled by both the state transition prior and the grey prediction algorithm. Since the grey prediction algorithm is a kind of model-free method and is able to predict the system state based on historical measurements other than establishing a priori dynamic model, the GP-PF can significantly alleviate the sample degeneracy problem which is common in SPF, especially when it is used for maneuvering target tracking. Simulations are conducted in the context of two typical maneuvering motion scenarios and the results indicate that the overall performance of the proposed GP-PF is better than the SPF and the multiple model particle filter (MMPF) when the tracking accuracy, computational complexity and tracking lost probability are considered. The performance improvements can be attributed to that the GP-PF has both model-based and model-free features.

Present paper utilizes the time evolution for estimating the soil moisture and vegetation parameter with Radar remote sensing data. For this purpose, vegetation ladyfinger has been taken as a test field and experimental observations have been taken by bistatic scatterometer at X-band in the regular interval of 10 days for both like polarization (i.e., Horizontal-Horizontal, HH-; Vertical-Vertical, VV-) and at different incidence angles. At this interval, all the vegetation parameters and scattering coefficient have been recorded and computed. Three similar types of field of size 5 x 5 m have been especially prepared for this purpose. The observed data is critically analyzed to understand the effect of incidence angle and polarization effect on scattering coefficient of the ladyfinger. It is observed that VV-polarization gives better result than HH-polarization and incidence angle 55^ο is the best suited to observe composite effect of vegetation ladyfinger biomass (Bm) and vegetation covered soil moisture at X-band. This analysis is further used for retrieval of soil moisture and biomass of ladyfinger using Neural Network. The important aspect of the retrieval algorithm is that it includes the time evolution. The retrieval results for soil moisture and Bm are in good agreement with the actual values of the soil moisture and biomass.

Two new triple band small size composite-resonator microstrip antenna configurations for wireless communications are presented in this paper. The proposed antennas, each is built of three resonant elements. Two types of compact short-circuited resonators are used; stepped impedance and quarter-wave resonators. The design procedure based on composing the antenna resonators is straightforward and can be applied to design any triple band antenna at three pre-specified bands using simple relations and design curves. The resonator integration has been performed to maintain single feed, reduce the overall antenna size, and preserve the quality-performance at each band. The two designed antennas are simulated, optimized, and realized on RT-Duroid substrate to verify the concept. Simulation and experimental results are in good agreement and demonstrate the performance of both triple band compact antennas.

In this paper, a quasi-optical Bessel resonator (QOBR) for generating approximations to Bessel-type modes at millimeter wavelengths have been designed and analyzed. A design approach is based on the quasi-optical techniques. In order to analyze the designed QOBR rigorously, a new method based on iterative Stratton-Chu formula (ISCF) is developed from the classical Fox-Li algorithm. And its validity is demonstrated. Numerical results reveal that at the output plane the intensity distributions of the Bessel-type modes of the QOBR are modulated by a bell-shaped envelope, and their phase patterns have a block-shaped profile except slight distortion on the edges of the element due to aperture diffraction. The effect of varying the parameters of the designed QOBR on the relevant output characteristics is also examined in our study.

A microwave method has been proposed for accurate complex permittivity measurement of thin dielectric materials partially filling the waveguide. The method employs propagation constant measurements at two locations of the sample inside its holder. It increases the accuracy of permittivity measurements of similar methods in the literature since it utilizes the measurements of the distances between the inner waveguide walls and sample lateral surfaces instead of directly measuring the sample thickness. It has been validated by comparing the measured complex permittivity of a thin Plexiglas sample by the proposed method with that of the method in the literature.

This paper presents a new design of miniaturized wideband bandpass filter using microstrip hairpin in multilayer configuration for X-band application. The strong coupling required for wideband filter is realized by arranging five hairpin resonators in two layers on different dielectric substrates. Since adjacent resonator lines are placed at different levels, there are two possible ways to change coupling strength by varying the overlapping gap between two resonators; vertically and horizontally. In this paper, simulated and measured result for a wideband filter of 4.4 GHz bandwidth at 10.2 GHz center frequency with fifth order Chebyshev response is proposed. The filter is fabricated on 0.254 mm thickness R/T Duroid 6010 and R/T Duroid 5880 with dielectric constant 10.2 and 2.2 respectively using standard photolithography technique. Two filter configurations based on vertical (Type 1) and horizontal (Type 2) coupling variation to optimize the coupling strength are presented and compared. Both configurations produce very small and compact filter size, at 5.0 x 14.6 mm² and 3.2 x 16.1 mm² for the first and second proposed filter type respectively. The measured passband insertion losses for both filters are less than 2.3 dB and the passband return loss is better than -16 dB for filter Type 1 and -13 dB for filter Type 2. Very small and compact filter is achieved where measured results show good agreement with the simulated responses.

A new microwave method has been proposed for simultaneous broadband and stable complex permittivity and complex permeability determination of magnetic and nonmagnetic materials. The method utilizes complex transmission scattering measurements at different frequencies. For a change in constitutive parameters determination, we considered zero-order and higher-order approximations. We have verified the proposed method from measurements of two medium- and low-loss materials with another method and available reference data in the literature.

A modified particle swarm optimization (PSO) algorithm applied to planar array synthesis considering complex weights and directive element patterns is presented in this paper. The modern heuristic classical PSO scheme with asynchronous updates of the swarm and a global topology has been modified by introducing tournament selection, one of the most effective selection strategies performing in genetic algorithms the equivalent role to natural selection, and elitism. The modified PSO proposed combines the abilities of the classical PSO to explore the search space and the pressure exerted by the selection operator to speed up convergence. Regarding the optimization problem, the synthesis of the feeds for rectangular planar arrays consisting of microstrip patches or subarrays of microstrip patches is considered. Results comparing the performance and limitations of classical and modified PSO-based schemes are included considering both test functions and planar array complex synthesis to best meet certain far-field radiation pattern restrictions given in terms of 3D-masks. Finally, representative synthesis results for sector antennas for worldwide interoperability for microwave access (WiMAX) applications are also included and discussed.

Studies of dual channel, polarisation agile, quad-ridge and octo-ridge feeds suggest that mode degeneracy in multi-ridge structures severely constricts operational bandwidths, for a large range of ridge dimensions. Mode characteristics in dual-ridge, quad-ridge and octo-ridge waveguide are examined in this paper, with a view to identifying both the nature of the degeneracy, and its implications for bandwidth. The results presented have been generated using a full-wave finite element electromagnetic field simulator.

In this paper, a novel multi-band EBG structure is presented. By making slots on Sievenpiper High Impedance Surface(HIS) to increase the inductance and capacitance, the resonant frequency of the EBG structure can be significantly reduced.Transmission line method is used to determine the band-gap of the EBG structure.The simulated and experimental results show that the novel EBG structure can provide multiple band-gap. This proposed EBG can be usefully applied to multiple frequency antennas and low profile antennas.

A bandpass filter (BPF) using CPW combined with microstrip is proposed. The target BPF is composed of two element filters built from combined CPW and microstrip structure. The design of element filter is based on the lumped elements approach with each circuit component built from a CPW or microstrip. In the circuit model, transmission zeros are created by the passband edges to enhance the signal selectivity. The element filter's characteristics are analyzed by the lumped L-C circuit model. Experiment is conducted, and a good agreement is observed between the measurement and simulation.

Wet antenna attenuation during rain events is examined through carrying out simulated rain experiments. These were conducted on the receiving antenna located at Penang, Malaysia. The findings from these experiments are used to estimate rain attenuation data for that path by adjusting the collected data for wet antenna attenuation. This was done for the 1-year period of March 2007 to February 2008 and includes average and worst month cumulative distribution functions. The results of the measurement indicated that the wet antenna effect is a significant attenuator, and should be included in a link budget. The measured attenuation values were 4 dB for the wet feed window and total reflector plus feed window attenuation value of 6.3 dB at 20.2 GHz, at a rain rate of 100 mm/h.

The paper presents the ionospheric effect on the power transmitted by satellite solar power station. Consequently, the Faraday rotation and losses due to ionospheric layer are calculated at 2.45 GHz frequency. It is observed that the fluctuation in the Faraday rotation in day time is found to be the maximum as compared to the night hours and. Loss due to depolarization is found to have the maximum value at noon hours for all the seasons (summer, winter and spring) however, the loss is the highest for summer season as compared to winter and spring season. This is logically correct because the ionization is the highest in summer in comparison to winter which gives rise to maximum electron content and maximum depolarization.

Ultra Wideband (UWB), an impulse carrier waveform, was applied at HF-VHF frequencies to utilize surface wave propagation. Due to the low duty cycle of the pulse, the energy requirements are significantly reduced. UWB involves the propagation of transient pulses rather than continuous waves which makes the system easier to implement, inexpensive and small. The use of surface wave propagation (instead of commercial SHF UWB) extends the communication range. The waveform, transmitter, receiver, modulation and channel characteristics of the novel system design will be presented.

The scattering of electromagnetic plane wave from an artificial object containing thin long perfectly conducting needles embedded in a homogeneous background material is characterized by parameters like positioning, orientations and lengths of needles. Firstly, models of random errors in positioning and orientation of perfectly conducting needles are proposed. Secondly, their effects upon ensemble averaged RCS is analyzed. It is investigated theoretically that increasing error in positioning and orientation of conducting needles reduces ensemble averaged RCS.

Inaccurate range estimates often restrict indoor positioning systems, resulting in a more remarkable drawback when using an already-deployed IEEE 802.11 network. This is the case of the time delay based location system that this paper deals with. The main causes of these inaccuracies are multipath and non-line-of-sight (NLOS) effects. These effects can be solved to a large degree by characterizing arrival times and range estimation errors. For this reason, this paper analyzes multipath and NLOS effects involved in the round-trip time (RTT) discrete measuring process, which is conducted before each range estimate. RTT observations obtained in this process for different real indoor environments provide useful statistical information that allows making the work extendable to other similar scenarios. Moreover, from this statistical information, the nodes in the network can estimate several parameters of the range estimates distribution while performing the location process. These are used to reduce the error caused by multipath components and to predict and correct the NLOS biases produced. In this way, the NLOS error is dynamically estimated and corrected, achieving better results than classical approaches based on static parameters.

Composites containing conducting inclusions are required in many engineering applications, especially, for the design of microwave shielding enclosures to ensure electromagnetic compatibility and electromagnetic immunity. Herein, multilayer shielding structures are studied, with both absorbing and reflecting composite layers. In this paper, fiber-filled composites are considered. For modeling absorbing composites with low concentration of conducting cylindrical inclusions (below the percolation threshold), the Maxwell Garnett theory is used. For reflecting layers, when concentration of inclusions is close to or above the percolation threshold, the McLachlan formulation is used. Frequency dependencies for an effective permittivity are approximated by the Debye curves using a curve-fitting procedure, in particular, a genetic algorithm.

A gas will breakdown in a high electric field and the mechanisms of this breakdown at DC and high frequency fields have been an object of study for the past century. This paper describes a method to induce breakdown in a uniform microwave field using a reentrant sub-quarter wave resonator. Slater's theorem is used to determine the magnitude of the threshold electric field at which breakdown occurs. The breakdown threshold is modeled using the effective electric field concept, showing that breakdown varies with pressure as E_bd=CP^m (1+(ω/ B·P)²)^1/2 where P is the pressure, B and C are fit parameters, and m was found experimentally to equal 1/2. This function exhibits a minimum at P_min=ω/B. Breakdown data from the literature for nitrogen at various microwave frequencies were found to exhibit breakdown minima at the pressure predicted by our own determination of B, further validating the model.

The excitation of metamaterial and non metamaterial, Electromagnetic (EM) modes and fields in an anisotropic, parallel plate waveguide (meeting Dirichlet and Neumann boundary conditions), is studied, using a modified coordinate transformation [3, 4] which reduces Maxwell's equations to the form of a Helmholtz wave equation satisfying Dirichlet and mixed-partial derivative boundary conditions. The EM modes and fields of the system are excited by a novel, slanted electric surface current excitation (Figs. 1 and 2) whose slant angle has been chosen to coincide with the surfaces of constant phase of the anisotropic modes which may propagate in the waveguide. Also presented, for comparison purposes, is the EM field excitation analysis of an isotropic parallel plate waveguide whose dimension, operating frequency, and source is identical to the anisotropic waveguide and whose material parameters are very close to those of the anisotropic waveguide. The analysis consists of several parts. Sections 1 and 2 of the paper describe the Helmholtz wave equation and boundary conditions that arise from use of the modified, coordinate transformation. In Section 3 the modal characteristic equation of the system is derived and in Section 4 this equation is solved to determine the propagating and complex (or non propagating) modes that may exist in the waveguide. For the anisotropic material parameters chosen in the paper, in Section 4, one of the propagating modes of the system was shown to be a metamaterial mode (also called a backward traveling wave, phase velocity and direction of real, positive power flow in opposite directions). An analysis in Section 4 was also presented from which the cutoff frequency of the waveguide could be determined. Sections 5-8 of the paper were concerned with using the complex Poynting theorem and an EM complex power reaction equation to study complex power and energy in the waveguide. The complex Poynting theorem and the reaction equation were also used to derive several power and reaction orthogonality relations that exist between the propagating (including non metamaterial and metamaterial modes) and complex modes of the systems. Using the orthogonality relations derived in Sections 5-8, in Section 9, an efficient matrix analysis based on the reaction equation of Section 8 from which the EM modes excited by a given slanted electric surface current (Section 5) could be determined is presented. The reaction-matrix analysis and the matching of EM boundary conditions near an electric surface current source were shown to be directly related. In Section 10, for comparison to the anisotropic waveguide study under consideration, a Green's function analysis was used to determine the EM fields that would be excited in an isotropic waveguide having EM characteristics similar to that of the anisotropic waveguide. In Section 11 wavenumber and modal orthogonality results were presented and in Section 12 the EM fields corresponding to a specific electric surface current example were calculated for both the anisotropic and isotropic waveguides. In Section 11, six tables of data for the anisotropic and isotropic cases giving numerical examples of the modal wavenumbers that were calculated for the propagating and complex modes of the system (Tables 1 and 2), numerical examples of the modal orthogonality relations that the waveguide modes satisfied (Tables 3 and 4), and numerical examples of the modal power that was transmitted by different propagating modes for anisotropic waveguide case (Table 5) and isotropic waveguide case (Table 6) were presented. In Section 12 for both the anisotropic and isotropic waveguides cases studied, plots of the EM fields near the surface current were shown to meet EM boundary conditions near the electric surface current and near the waveguide walls to a high degree of accuracy. The conservation of complex and reaction power as delivered by and radiated from the electric current source was observed to hold for both the anisotropic and isotropic waveguides studied to a high degree of accuracy.

The characteristics of a slot antenna on a perfectly conducting elliptic cylinder coated by nonconfocal chiral media are investigated. The structure is fed with a line source or plane wave. The analysis is carried out by expressing the fields in and around the cylinder in terms of Mathieu and modified Mathieu functions using the separation of variable and exact boundary value technique. The unknown aperture field is expressed in terms of Fourier series with unknown expansion coefficients. The expansion coefficients are found by applying the boundary conditions on different surfaces and employing the addition theorem and orthogonality properties of the Mathieu functions. For TM and TE cases some numerical results of the antenna gain for co- and cross-polarized waves are presented and discussed.