This paper presents a comparative study on practical evaluation of measurement uncertainty for complex-valued RF and microwave quantities in polar coordinate. The measurement uncertainty is first evaluated in rectangular coordinate to avoid the biased effect, and then transformed into the desired polar coordinate. In this work, uncertainty coordinate transformation from rectangular coordinate to polar coordinate is focused and performed in two ways; the law of propagation of uncertainty and the coordinate rotation. Their performances are compared through practical evaluations and simulations, and found to be highly consistent when the uncertainty region is distant from the origin of a complex plane.

An integrated compact circular-polarized annular ring slot antenna is proposed in this paper. It consists of an annular ring slot radiator and a hybrid patch coupler. The hybrid patch coupler is integrated with the annular ring slot antenna to radiate the circular-polarized wave, while size of the antenna remains the same. Both the impedance bandwidth and axial ratio bandwidth of the proposed design almost cover the entire UHF band of RFID system and it has the features of easy fabrication and low cost. To verify the proposed design, a prototype is fabricated. Measured results agree well with the simulated results.

A compact multiple band-notch ultra-wide band (UWB) band-pass filter (BPF) with surface area of 18 x 12 mm² is introduced in this article. The proposed filter is a combination of novel symmetrically tapered elliptic rings (STER) and contiguous split ring resonators (SRR), with stepped impedance resonator (SIR) structure to realize the multi-band notch UWB pass band characteristics. In the proposed structure, band-notches are generated for interfering microwave bands such as, WiMAX, WLAN and X-band applications. These notches are achieved by optimizing structural parameters of SRR sections. The proposed filter is fabricated on RT/Duroid 5880 substrate with ε_r = 2.2 and thickness of 0.787 mm. The fabricated prototype is measured and a good agreement between simulated and measured results ensures suitability of the proposed filter for UWB applications.

Spacial coaxial resonator plays an important role in spacial system. However, its multipactor effect has not been reported so far. This paper presents a novel type of coaxial resonator structure with low multipactor risk. Compared with conventional coaxial resonator structures, the proposed structure improves the multipactor threshold of filters nearly 3 dB. Experimental results and 3D full-wave analysis show good accordance with the predicted characteristics.

Evaporation duct is a manifest phenomenon that can affect microwave propagation seriously with low elevation angles near the sea surface. As an important parameter to describe the characteristic of the evaporation duct, duct height can be estimated from radar sea echo using a technique called as "refractivity from clutter". In this study, we proposed a novel approach to estimating the evaporation duct height. The signal power received by a ground-based GPS receiver is used when the GPS satellites rise or set at the local horizon over the sea. A forward propagation model and genetic algorithm are adopted to implement this method. The performance is evaluated via numerical simulation for inferring evaporation duct with different height. The results showed that the proposed method is well effective, especially for the conditions with higher evaporation duct height.

This paper presents an analytical formula to evaluate even- and odd-mode characteristics of infinitely parallel coplanar waveguides (CPW) with the same dimensions in each CPW, given name as periodic coplanar waveguides (PCPW). The analysis yields a closed-form expression based on the quasi-TEM assumption and conformal mapping transformation. Calculated results show that both the even- and odd-mode characteristic impedances are in good agreements with the results generated by numerical solvers and available experimental data. The results are important especially for highly demand on miniaturization of circuit design to place multiple CPWs in parallel.

Based on the altitude-dependent model of the ITU-R slant atmospheric turbulence structure constant model, we present scintillation index calculations for a partially coherent Gaussian Schell-model (GSM) beam under all irradiance fluctuation conditions. The longitudinal and radial components of the scintillation index are treated separately. Our results correctly reduce to the result of the horizontal path with atmospheric structure constant fixed; and simplify to a fully coherent Gaussian beam with source coherence parameter ζ representing unit. The numerical conclusions indicate that within specific source and parameter ranges, a partially coherent GSM beam is capable of offering less scintillation in comparison with the full coherent Gaussian beam. Before the maximum value of the scintillation, the scintillation index of the partially coherent GSM beam will decrease with the increased altitude. However the off axis radial scintillation index will vanish when the Rytov variance is infinity.

According to literature, a significant and up to date research direction to increase the performance level of automatic target recognition (ATR) systems is focused on the use of information coming from an appropriate set of EM sensors and high-quality decision fusion techniques, respectively. Consequently, in this paper a genetic optimized version of Sugeno's fuzzy integral is discussed. In addition, using a real database belonging to the high-resolution radar (HRR) imagery, the superiority of the proposed decision fusion technique related to its standard version and other well-known decision fusion methods is also demonstrated.

A new type of cascaded series feed beamforming networks (BFNs) is introduced. The network architecture is based on a dual-series Nolen matrix topology. It is able to produce tapered output amplitude distributions from NxN configurations. The general concept, analysis and systematic design of the BFNs are given. The networks are designed and intended to be used mainly for low Sidelobe Level (SLL) linear Multibeam Antennas (MBAs). Several design examples are presented, along with fabrication and measurements of an S-band prototype.

In this paper we present seasonal results of the effective earth radius factor distribution in South Africa using recently (2007-2009) acquired radiosonde data from the South African Weather Service (SAWS) for seven locations in South Africa. Two data modeling methods are used to formulate the solution for the distribution of the effective earth radius factor. The seasonal effective earth radius factor statistics obtained from the radiosonde measurements are then interpolated, gridded and presented in contour maps to cover the rest of the country for the four seasons defined by ITU-R recommendation P.453-12. The Integral of Square Error is used to check the performance of the data modeling techniques while the Root Mean Square Error is used to compare the performance of the different interpolation methods used.

In this paper, a novel algorithm named multi-scan mixture particle filter is proposed for joint detection and tracking for a varying number of targets. The posterior distribution of multiple target state in a single-target state space is a multi-mode distribution with each mode corresponding to either a target or clutter. A general global posterior distribution is adopted in this work, which consists of existing components and new components. The new components are generated at each time step to capture the new modes due to newly appeared targets or clutter. In order to distinguish targets from clutter, multiple scan information is incorporated. The history of each component's associate weights is stored in a multi-scan sliding window, which is used to judge whether the component is from a target or clutter. Moreover, a novel sampling method which combines the likelihood sampling and prior sampling is proposed to draw particles from the desired parts of the state space at each time step. From the simulation results, it could be seen that the proposed algorithm can effectively detect the appearance/disappearance of the targets as well as track the existing target.

In this paper, design and analysis of omnidirectional single feed circularly polarized, wide axial ratio beamwidth resonant sidefed bifilar helix antennas that do not require a ground plane is presented. The simulation and measurement results show that side-fed helix antennas of various radii gives near perfect circular polarization (CP) almost over the whole sphere except at and around nulls, at a certain turn angle by properly proportioning the area of loop (A) with the product of pitch (p) and radianlength (l) of helix. Helix antennas with smaller radii give axial ratio (AR) close to one at higher values of turn angle with lower value of resonant input impedances but CP is less sensitive to inaccuracy in turn angle. However helix antennas with larger radii results in AR close to one at lower values of turn angle and provides better values of input resistance but its AR is more sensitive to variations in turn angle. The simulated results show that the polarization solid angle beamwidth (for AR ≤ -3 dB) varies from 3.96π to 4π steradian. The gain and 3dB beamwidth of the antennas are 2dBi and 90° respectively. The polarization bandwidth varies from 34% to 65%. The simulated results are verified by experimental measurements.

New multiband integrated slot antennas for mobile handsets are presented for GSM, DCS, PCS and WCDMA, GPS and WIFI 2.4 GHz. Prototypes, both simulated and measured, are realised in the metal back cover away from the hand. Perturbations due to tissue proximity are simulated using a CTIA compliant hand phantom.

A novel compact coplanar waveguide (CPW)-fed printed antenna with triple bands for WLAN and WiMAX applications is presented. By using a parasitic circular patch, a pair of symmetrical inverted-L strips and a 50-Ω transformer, the antenna can effectively provide a good input impedance matching. The tuning effects of the ground size, the parasitic circular patch and the symmetrical inverted-L strips to the resonance and matching condition are then examined, and the prototype of the proposed antenna is further fabricated and measured. The experimental and numerical results exhibit that the antenna has impedance bandwidth for S₁₁≤-10 dB of 2.32-2.80 GHz, 3.06-4.13 GHz and 5.03-6.04 GHz, which can cover both the WLAN 2.4/5.2/5.8 GHz bands and the WiMAX 2.5/3.5/5.5 GHz bands. Also, a stable monopole-like radiation pattern and an average antenna gain of 3.06 dBi across the operating bands have been obtained.

This letter demonstrates a technique for a folded slot antenna fabricated on low resistive silicon wafer, using pre-etched cavity and Benzocyclobutene (BCB) support membrane. The most distinctive feature of this method is that a cavity is pre-etched before the antenna fabrication process using low-cost potassium hydroxide (KOH) wet etching. BCB membrane is employed to support the antenna above the cavity for its low permittivity as well as excellent thermal and mechanical stability. The fabrication process discussed in detail and the fabricated antenna was characterized. Experimental results show that the antenna resonates at 15.4 GHz with a very wide impedance bandwidth, up to 14.6%.

In this article, artificial aerosol metaparticles are investigated. These particles are based on interacting single split rectangular resonators (SRRs) imprinted on a one-sided thin dielectric substrate. These particles produce sharper transmission bandstops with adjustable bandwidths compared to conventional artificial aerosol obscurants like fibers, spheres, discs. The particle design is performed in the microwave region with the intention to be scalable to the infrared. Particles with couplings between two, three, and four SRRs are introduced. Numerical simulations and experimental measurements of the transmission parameter of the particles are introduced and compared with fibrous aerosols. These particles may be used as good electromagnetic obscurants in the atmosphere.

A spacecraft will experience the well-known ``blackout'' problem in the re-entry into the Earth's atmosphere, which results in communication failures between the spacecraft and ground control center. It is important to study the blackout mitigation method. The effects of external magnetic field on electromagnetic wave propagation in plasma are studied by theoretical and experimental methods in this paper. The numerical results show that the attenuation of electromagnetic wave in plasma is reduced by the presence of a magnetized field. The propagation properties of electromagnetic wave in unmagnetized and magnetized plasma have been studied experimentally with plasma torch, and the experimental results are in good agreement with the theory. Both the theoretical and experimental results indicate that magnetic window is an alternative and promising way to improve the radio blackout issue.

Broadband beamforming has been an important issue on antenna array processing due to many practical demands on communication, radar, or sonar applications. Although several effects deteriorating array performance have been addressed for narrowband beamforming, few of them are considered for the broadband scenario. Besides, the definition of output signal-to-interference plus noise ratio (SINR) and the way to simulate broadband signal sources are usually vague, which further obstructs the development of broadband beamforming. In this paper, the performance of discrete Fourier transform (DFT) beamformers operating in block processing and sliding window modes are investigated when the correlation matrices are known or estimated by finite data samples. The output SINR of DFT beamformers is well-defined, and the generation of broadband signals is clearly introduced. Simulation results with respect to the signal bandwidth, the number of frequency bins, and the number of data samples are presented for illustration and comparison.

There is an impetuous need for easy-to-build electrical machines with high specific thrust for various applications. The paper deals with a new modular variable reluctance tubular machine. It is a transverse flux machine without permanent magnets. Its construction is detailed and the novelty of the proposed structure is emphasized. A sample machine is analyzed by analytical and numerical means. The results of the analyses are validated by testing a laboratory model of the motor.

In this paper, a dual-fed circularly polarized antenna design with high isolation is presented for radio frequency identification(RFID) reader. The proposed antenna is excited by two fed ports connected with a circular split-ring microstrip line underneath the ground plane. A radial aperture in the ground plane provides coupling between the split-ring microstrip and radiating patch. For multiple RFID band requirements, the dimension of the aperture can be modified to obtain high isolation on different RFID Band. Finally, an antenna prototype for China RFID Band(920-925 MHz) is fabricated. The measured results agree well wit13h simulation, and show 10-dB matching bandwidth of 18%(820-1000 MHz), 3-dB axial ratio(AR) bandwidth of 11%(854-960 MHz), and 25-dB isolation bandwidth of 11 MHz(917-928 MHz).