In this paper, we present improved Lumped-Parameter Models for simulation of a Interior Permanent Magnet Synchronous (IPMS) machine to calculate PM flux linkage, and Q and D-axis inductances which can be used for torque calculation. These improved models include all details of flux barriers and air bridges of rotor and also the eect of saturation in central posts and stator core. To validate the accuracy of these models, results are compared with the Finite Element Method results for a candidate three-layer IPMS machine.

A novel dual-band circularly polarized monopole antenna fed by coplanar waveguide (CPW) is proposed. Deformed monopole and asymmetrical ground are utilized to achieve dual-band characteristic, by adjusting the tuning stub close to the deformed monopole, the antenna can be further improved to a good performance. Measured results show that the proposed antenna impedance bandwidth is 1.44 GHz centered at 3.42 GHz for the lower band and 400 MHz centered at 5.2 GHz for the upper band, the 3-dB axial ratio bandwidth is 900 MHz centered at 3.25 GHz and 400 MHz centered at 5.1 GHz respectively. The measured results agree well with the simulated results.

A compact dumbbell-shaped split-ring DGS is introduced between array elements of a sixteen-element microstrip array in order to reduce the mutual coupling between antenna elements and eliminate the scan blindness. The proposed DGS is inserted between the adjacent rectangle-shaped slotted microstrip antenna elements separated by 0.35λ, as a technique to suppress the radiation in the horizontal direction. Simulated results show that a reduction in mutual coupling of 36 dB is obtained between elements at the operation frequency of 2.45 GHz (WLAN band). The scan properties of microstrip array with and without DGS have been studied, and the result indicates that the scan blindness of the array has been well eliminated because of the effect of the DGS. We have developed experimental models that have proved the concept of scan blindness elimination. Finally, the influence of other antenna parameters at the presence of DGS in the array system has been studied. Prototype antennas of sixteen-element array with and without resonator have been fabricated, measured, and the idea has been verified. A good agreement is observed between measured and simulated results.

According to a recent European Union report, lighting represents a significant share of electricity costs and the goal of reducing lighting power consumption by 20% demands the coupling of light-emitting diode (LED) lights with smart sensors and communication networks. This paper proposes the integration of these three elements into a smart streetlight, which is based on LEDs and a 24 GHz phased-array (Ph-A) front-end (FE) designed in low-cost 90nm complementary metal-oxide-semiconductor (CMOS) technology. The selected FE's architecture allows the implementation of transceivers as well as Doppler radar sensors. Furthermore the Ph-A technology is applied to the Doppler radar sensor in order to realize multi-lane road scanning and pedestrian detection. The radar sensor is used to make the streetlight eco-friendly by turning on the lamp only when necessary and to measure traffic parameters such as vehicle speed, type and direction. Intercommunication between the streetlights is based on a time-sharing mechanism and uses the same FE reconfigured as transceiver. Thanks to this functionality, the recorded traffic information is relayed through adjacent streetlights to a control center, and control commands and warnings can be spread through the network. The system requirements are derived assuming a simplified model of the operating scenario with a typical inter-light distance of 50 m and line-of-sight between lights. The radar range is around 60 m, which allows for continuous coverage from one streetlight to the adjacent one. Meanwhile, a communication range of 140 m is derived as a fundamental requirement for reliable communication between streetlight sensors because it allows bypassing of one node in case of failure. For the developed building blocks --- a low-noise amplifier, a variable-gain amplifier, a voltage-controlled oscillator and a vector modulation phase shifter --- the design methodology is presented together with measurement results. The system feasibility is proved by means of a system analysis based on the measured data from the implemented blocks and the state of the art performances for the missing parts. The requirements are fulfilled with a total power consumption of around 375 mW in Doppler radar sensor mode and around 190 mW in transceiver mode. To the authors' knowledge, this kind of integration is new and overcomes some limitations of the currently used solutions based on infrared sensors and low-throughput communications.

Rain attenuation is a major source of impairment to signal propagation at microwave and millimeter wave bands. The procedures for the estimation of rain attenuation value regard to microwave signals however rely mainly on 1-minute rain rate statistics, particularly those obtained locally from experimental measurement campaigns over a given location. In this paper, we present recent results on 1-minute rain rate statistics required for satellite and terrestrial link designs, as obtained from a 2-year measurement over Akure, Nigeria. The performance of the existing rain rate models: Rice-Holmberg (RH) model, the Kitami model, Moupfouma model and the global ITU rain rate model were tested based on four metrics namely: Prediction error, Root Mean Square Error (RMSE), Spread-Corrected Root Mean Square Error (SC-RMSE) and the Spearman's rank correlation. Result indicates that no single model completely outperforms all others. Interestingly, the RH model is particularly best behaved over the distribution, while the Moupfouma model performs suitably well. Others seem to vary largely from the measured rain rate distribution. Results for the rain rate exceeded for 0.01% of the time agrees with earlier estimates for the cumulative rain rate distribution derived from higher integration-time statistics over this tropical site.

In this paper, two miniaturized (20 x 20 mm²) coplanar waveguide fed slot antennas are proposed. Both the antennas are characterized by ultra wide impedance bandwidth while one of them has an additional narrow band near 2.5 GHz. The radiating element of the proposed antennas is a modified rectangular geometry which is excited by a 50 ohm line. The radiating element of the proposed antennas is a modified rectangular geometry which is excited by a 50 ohm line. The slot in the ground plane is stair case shape for UWB antenna and octagonal shape for the dual-band antenna. By modifying the slot and adding a λ/4 length metallic stub, an extra resonance is created for the dual-band antenna. The measured impedance bandwidth of the UWB antenna is 7.8 GHz (3.4-11.2 GHz). The impedance bandwidths of the dual-band antenna are 150 MHz (2.45-2.6 GHz) and 8.4 GHz (3.2-11.6 GHz). The radiation patterns of the proposed antenna are found to be bi-directional in E-plane and omnidirectional in H-plane. All the measured and simulated results are in good agreement.

First, we report on the design, simulation and measurement of a 2-4 GHz conformable antenna optimized for skin contact and implemented on a flexible printed circuit for integration into a wearable device. Second, we experimentally verify the suitability of appropriately long (~10 cm) microstrip traces for the wearable system signal distribution network, which features varying radii of curvature. Consequently, the contribution of the here reported work is two-fold. First, the experimental results obtained both with breast phantoms and on-body measurements, demonstrate a return loss below -10 dB in the desired frequency band. Phantom results also show a through-breast transmission coefficient of above -40 dB at the centre frequency of 3 GHz. Second, and essential for signal integrity in our target application, the results show that the longitudinal curvature of such a microstrip does not increase transmission line losses.

A high gain wideband antenna array with an omnidirectional radiation pattern is presented for base station. The antenna array is composed of four elements and a circular four-way power divider. The proposed planar antenna element consists of four pairs of arc dipoles and a balun, which can achieve a better impedance match and a wider frequency range. Furthermore, the conductor ground of the power divider with a larger size than the element is placed under the four antennas, which can also enhance the peak gain. The antenna array is simulated, fabricated and measured. The measurement results show that the proposed antenna array can achieve a bandwidth from 1.62 GHz to 2.43 GHz or a relative bandwidth of 39.4%. The antenna array has a peak gain of 6.4-7.2 dBi in the work band and obtains a radiation efficiency of 88%. The simulated and measured results show that the proposed antenna array is a good candidate as a base station antenna for GSM, PCS, and UMTS applications.

In this paper, a three-band antenna with small size 50×15×0.8 mm³ is developed. The multi-broadband antenna consists of strip-1, tstrip-2, Br-1, Br-2 and S-strip. The lengths of strip-1, strip-2 are close to λ/4 at 680 MHz, 850 MHz and λ3/4 at 2.04 GHz, 2.55 GHz, respectively. S-strip is close to λ at 5.2 GHz and λ3/4 at 3.7 GHz. In addition, two tuning stubs Br-1 and Br-2 connected to strip-2 can further improve the impedance matching. Then six key resonances are excited: 680 MHz, 850 MHz, 2.04 GHz, 2.55 GHz, 3.7 GHz and 5.2 GHz. There exists electromagnetic coupling (EMC) among them, and as a result of the comprehensive effect of the structure, three wide-bands are produced: 660-1050 MHz, 1.60-3.75 GHz, 5.25-6.50 GHz. That is, the operation band covers full LTE700/2300/2500 (1710-2690 MHz)/GSM850/900/ (680 M-960 M)GSM1800/1900/WiMAX3.5G (3400~3650 MHz)/5.4-GHz (5250~5850 MHz)/ UMTS (1710-2170 MHz). The return loss is better than -6 dB. The peak gains also satisfy the requirement for practical application.

Fresnel Zone Plate Lenses (FZPLs) are transparent-opaque lenses that filter the desirable phase. The centred Fresnel lenses have a strong back radiation towards the feed. In order to solve this drawback, offset feeding or offset pointing lenses are used. In this work, both offset FZPLs are studied using an optical physics method and experimentally characterized in the millimeter band. Two prototypes have been manufactured and measured, presenting a narrow beamwidth. The characteristics of pointing of this beam are studied depending on the feed gain. This work shows the pointing characteristics of the lenses, simply moving the lens in a plane.

A coupled oscillator array using push-push oscillators and resonator type coupling circuits is presented. In the proposed oscillator array, the coupling circuit operates at the fundamental frequency and the output signal is the 2nd harmonics. The adjacent oscillators are connected via the coupling circuits. The coupling circuit is used to synchronize the oscillators and control the phase difference of the output signals. In this study, a three elements push-push oscillator array has been designed in Ku band. The measured phase shift between the output signals of the adjacent oscillators is 511 degrees at the maximum.

This paper presents a compact tunable bandpass filter that is based on open split ring resonator to achieve high out-of-band rejection. Exact equations and design procedures are given based on strict theoretical analysis. By loading the varactor diodes, the center frequency and bandwidth of the bandpass filter could realize reconfigurable. Then defected ground structure was adopted in the input and output ports for the sake of high out-of-band rejection. In order to verify the result of theoretical analysis, a compact tunable bandpass filter with defected ground structure, whose range of frequency was 1.61 GHz~1.82 GHz and range of relative bandwidth was 8.3%~24.8%, had been simulated and fabricated. Good agreement between the measured data and the anticipated results is achieved.

In this work, new ``extended gauge transformations'' involving current and fields are presented. The transformation of Maxwell's equations under these gauges leads to a massive boson field (photon) that is equivalent to Proca field. The charge conservation equation and Proca equations are invariant under the new extended gauge transformations. Maxwell's equations formulated with Lorenz gauge condition violated give rise to massive vector boson. The inclusion of London supercurrent in Maxwell's equations yields a massive scalar boson satisfying Klein-Gordon equation. It is found that in superconductivity Lorenz gauge condition is violated, and consequently massive spin-0 bosons are created. However, the charge conservation is restored when the total current and charge densities are considered.

Novel 2-D Time Domain Electric Field Integral Equations (TD-EFIE) are established in order to predict transient response of a wire enclosed within a rectangular cavity. The wire and cavity are excited by an external incident transient electromagnetic wave through a slot in the cavity wall. The formulation of the TD-EFIE is based on equivalence principle and boundary conditions taking account the effect of reflection from cavity walls. The equations are efficiently solved by Method of Moments. The transient unknown coefficients of the electric current at the wire and magnetic current at the slot are approximated using a set of orthonormal temporal basis functions derived from Laguerre Polynomials. The analysis demonstration is presented to prove that the novel TD-EFIE combined to MoM is able to solve this critical problem. No late-time instability is encountered.

This paper reports design of a new dual-band T-type impedance transformer also exhibiting DC-blocking feature. The design aims at achieving matching for frequency-dependent complex loads having distinct values at two arbitrary frequencies to Z_s (here, 50 Ω). A step-wise analysis on the developed dual-band impedance transformer provides simple closed-form design equations. The design is verified by extensive simulation in Agilent ADS. For experimental verification a PCB prototype is fabricated using FR-4 material, operating at 1.45 GHz and 2.61 GHz. A good result is obtained confirming the theory and simulation.

In this paper, a co-prime symmetric sparse cross array is employed to estimate two-dimensional (2-D) direction-of-arrival (DOA). Some special forth-order-cumulants (FOCs) of array received data are used to construct a high-order matrix that is equivalent to a cross-covariance matrix based on two uniform linear arrays. After some modifications, an existing 2-D DOA estimation algorithm becomes more effective, and it shows further improved performance when the co-prime symmetric cross array is utilized. Numerical simulations demonstrate the effectiveness of our methods.

The static circuit parameters extracted from the field results of non-uniform microstrip line provides an efficient way to predict dynamic effect of non-uniform structure. The predictable frequency range of the static circuit parameters on prediction of the transmission characteristics of step microstrip line is researched in this paper. The circuit parameters are extracted from the full wave results of step line, respectively, at three frequencies (9 GHz, 15 GHz and 20 GHz). On one hand, the time domain transmission characteristics of step line can be solved from the equivalent circuit constructed by these extracted circuit parameters. On the other hand, the frequency domain S-parameter can be derived by the static distributed characteristic impedance. By comparing these time and frequency domain results obtained from the static circuit parameters with those obtained directly from the full wave method, the available condition of the static circuit parameters of the step microstrip line can be analyzed. This comparison shows that the static circuit parameters can be used in frequency bands from DC up to 20 GHz. To verify the accuracy of the static parameters used to predict the transmission characteristics of step line, the measured S₁₁ is also given for comparison with static circuit parameters measurements.

Based on a space folding transformation, we propose a new way to hide an object in full space,namely, to cover-up the scattering of the hidden object with the scattering of a background object so that only the scattering of the background object can be detected by an outside observer and the hidden object disappears electromagnetically (a very weak ``ghost image'' or perturbation may appear inside the strong background object image in an experiment). The present method is essentially different from previous methods of cloaking an object. This work furthers efforts to achieve invisibility and conceal an object in a real environment in full space.

Microwave tomography (MWT) and a radar-based region estimation technique are combined to create a novel algorithm for biomedical imaging with a focus on breast cancer detection and monitoring. The region estimation approach is used to generate a patient-specific spatial map of the breast anatomy that includes skin, adipose and fibroglandular regions, as well as their average dielectric properties. This map is incorporated as a numerical inhomogeneous background into an MWT algorithm based on the finite element contrast source inversion (FEM-CSI) method. The combined approach reconstructs finer structural details of the breast and better estimates the dielectric properties than either technique used separately. Numerical results obtained with the novel combined algorithmic approach, based on synthetically generated breast phantoms, show significant improvement in image quality.

A novel multiband, dual-polarization, beam-switched dual-antenna design, covering some LTE and WLAN bands, has been proposed for indoor base stations. The proposed design consists mainly of dual modified monopole antennas. The horizontal antenna consists of four printed monopole elements, and the control circuit using p-i-n diodes has been implemented for feeding to each monopole element. The vertical monopole antenna beam patterns are controlled by reconfigurable frequency selective reflectors (RFSR) technique. The p-i-n diodes have been utilized for switching mechanism to feed the four RFSR. The measured and simulated results indicate that the antenna system possesses multiband and dual polarization. It has been observed from the simulated and measured reflection coefficients |S₁₁| that the presented dual antenna system supports both LTE (1.7-2.1 GHz) and WLAN (2.5 GHz and 5.8 GHz) band frequencies. Moreover, the radiation characteristics show dual-polarization behaviors of the presented antenna system and beam switching states suitable for small cell indoor-base stations.