Ultra Wideband (UWB) has been deliberated as a promising technology for short-range wireless communication with large unlicensed frequency band for commercial, enterprise private and public uses. Designing an antenna of compact size for portable wireless devices is one of the challenges especially for UWB based wireless communication technologies. In this paper, a novel smiley fractal antenna, employed with N-notch feed and modified ground plane, is designed and developed to achieve the desired characteristics. The proposed antenna is of compact size with dimensions of 34×32×1.6 mm³, fabricated on an FR-4 substrate with ε_r=4.4. The radiation pattern of the proposed antenna is omni-directional with a maximum gain of 4.83 dB and efficiency of 93.55% obtained through 3D electromagnetic simulation software tools. The simulated results are compared with measured ones using RF equipment. The results obtained show that the proposed Smiley Fractal Antenna (SFA) is a suitable candidate for UWB wireless communication application.

A new planar engineered material structure, which has multiple Fano resonances at the terahertz range of frequency, is presented. Starting with a double Fano resonance structure, it is shown that by considering several unit cells as a larger unit cell and creating new asymmetries in the super-cell, we can have five Fano resonances in one structure. Analysis of current distributions at resonance frequencies clarifies the origin of different resonances. We show that all of these resonances come from different arrangement of magnetic dipoles.

A novel design of multiband probe-fed stacked patch antenna for Beidou Satellite Navigation System (BDS) and Global Position System (GPS) applications is proposed. The presented antenna covers BDS-1 L (1616±5 MHz), BDS-1 S (2492±5 MHz), BDS-2 B₁ (1561±5 MHz), and GPS L₁ (1575±5 MHz) frequency bands. Excellent high port isolation and Circular Polarized (CP) performance are achieved by introducing four metallized holes which are strictly symmetrical about the centre of the patch antenna. The proposed antenna is fabricated, and its performance is verified in measurement.

We propose a method to recognize targets by using the signature of jet engine modulation (JEM) generated by the rotating blades in jet engines. The method combines time-frequency transform, 2-dimensional (2D) principal component analysis, and a nearest-neighbor classifier. In simulationsusing five propellers composed of isotropic point scatterers,the proposed method was insensitive to signal-to-noise SNR variation; this insensitivity wasa result of the effective 2D time-frequency feature and the noise suppression by the matchedfilter. In simulations using a reduced training database, the result was most sensitive to variation in the rotation velocity of the blades.

This paper describes the working principle of a three-dimensional (3-D) holographic microwave imaging (HMI) method for imaging small inclusion embedded in a dielectric object. Using published dielectric properties of various materials, a 3-D mathematical model is developed under the MATLAB environment to validate the HMI on various dielectric objects. Results indicate that the 3-D HMI has an ability to produce a 3-D image and detect small inclusions embedded within a dielectric object. Several potential applications of the 3-D HMI method includes biological tissues imaging, security screening and packaged food evaluation.

The method of auxiliary sources MAS, presents a promising alternative to methods based on discretization, currently used for solving scattering problems. The optimal choice of the auxiliary surface and the proper allocation of radiation centers play a crucial role in ensuring accuracy and stability of the MAS. This approach is considered an open issue and can be investigated numerically. In this paper, we propose a systematic and fully automated technique leading to determine the optimal parameters of the MAS for arbitrary shaped obstacles (partially or fully penetrable) for scattering problems.

A near-field resonant parasitic (NFRP) antenna is presented. Unlike the conventional NFRP antenna, which is fed by coaxial cables, the topology is driven by a planar ``monopole''. In this way, the antenna and the front end circuit can be designed in a single plane, which is crucial for system integration. The radiator is electrically small (λ₀/19.3 × λ₀/10.47 × λ₀/76.4) while reaching a high efficiency (94%) and a good bandwidth (85 MHz). The operating frequency and input impedance are easily tailored. Measured results verify the working mechanism.

A novel multi-layer third-order substrate integrated waveguide (SIW) bandpass filter with improved lower stopband performance is proposed. TE₂₀₁-mode in folded-SIW cavity is utilized to implement negative cross coupling, and the TE₁₀₁-mode is taken as a non-resonating node (NRN) for implementing bypass coupling. A circular aperture etched on the middle metal layer is used to realize coupling between source and the second SIW cavity. Then, three transmission zeros located below the passband can be obtained to improve stopband attenuation. Meanwhile, better spurious suppression performance above passband is achieved. A filter sample is designed and fabricated with multi-layer low-temperature co-fired ceramic (LTCC) technology. The measured S-parameters agree well with the simulated ones, with its predicted good performance.

To remotely detect corona discharge from High-Voltage Direct Current (HVDC) transmission lines, a detecting system combining detecting platform and data progressing system is designed. Detecting platform is developed resorting to the principle of differential noise reduction, which can fulfill narrow-band detection breaking away interference from broadcasting and easily catch the electrostatic discharge signal. To get rid of interference from spark discharge, a data progressing system containing feature extractions, clustering and recognition technologies is developed. Clustering is realized by extracting five discharge features, including peak factor, form factor, skewness, kurtosis and mean square error. The unsupervised clustering Fuzzy C-Means (FCM) method is used to achieve fast separation for electrostatic discharges and provide training set for pattern recognition. Pattern recognition resorts to Support Vector Machine (SVM) method. For comparison, Back Propagation (BP) and Learning Vector Quantization (LVQ) approaches are taken to test the recognition ability. The results show that SVM recognizer with a recognition rate of 97.5% achieves higher performance than BP and LVQ methods. It can be concluded that the detecting system can be an interesting alternative for electrostatic discharge detection.

Two exact approaches to synthesize metasurfaces for time-harmonic waves are discussed. The first approach is a spectral approach based on wave momentum conservation. Here, the spectral approach is applied to scalar and paraxial wave transformations. This approach effectively allows the arbitrary translation of the transformation plane parallel to the metasurface. The second approach is a direct-space approach based on the extraction of the susceptibility tensors of the metasurface elements. This approach is applied to vectorial field transformation and can be used for single or multiple transformations. An example of wave transformation by a metasurface is illustrated for each of the two approaches.

In this paper, an efficient spectral signature based chipless RFID tag is presented, where 4^N number of words can be coded using only N number of resonators. As data bit encoding element, the proposed tag utilizes a number of modified complementary split ring resonators (MCSRR). A novel resonance detuning mechanism proposed here allows the use of an MCSRR to independently encode two data bits instead of one bit. Compared with two separate rings based CSRR, the proposed MCSRR occupies 56% less area and also reduces the resonance bandwidth requirement by more than 60%. The multiresonator circuit and the UWB antennas are implemented on a thin (0.127 mm) substrate with only single sided metallization. The proposed tag has great prospect to yield an ultra-low cost chipless RFID tag that may replace barcode in the long run.

A dual-polarized L-probe fed microstrip patch antenna with high isolation and low cross-polarization levels is proposed. The proposed antenna has been designed and analyzed by using commercially available software --- High Frequency Structure Simulator (HFSS) based on the finite element method algorithm and a simple resonant equation and Computer Simulation Technology Microwave Studio (CST MWS) based on the finite-difference-time-domain algorithm. A prototype antenna is built and tested. The return loss has been compared between measured and simulated data under the criterion of VSWR less than 2 through out the designed 4.95 to 5.05 GHz frequency range. The measured isolation between two ports is higher than 22 dB and the gain is larger than 3 dBi. The cross-polarization levels in both E and H planes are better than -21 dB, along with fair regular radiation patterns.

Metamaterials provide the opportunity for designers to create customisable artificial materials by independently tailoring the electric and magnetic response of sub-wavelength geometric structures to electromagnetic energy. Due to the increased complexity of these geometric structures, exacerbated by the increased interest in generating inhomogeneous and anisotropic metamaterials, direct optimisation of these designs using conventional approaches often becomes impractical and limited. In order to alleviate this issue, we propose an alternative optimisation approach which exploits the Kriging methodology in conjunction with an adaptive sampling plan to simultaneously optimise multiple conflicting objectives. Results show the effectiveness of the outlined algorithm in calculating a uniform spread of optimal trade-off designs, balancing the real and imaginary components of the refractive index over a wide range of values.

We propose to analyze the aperture and ITO layer presence of a modified transverse electromagnetic (TEM) cell. This TEM cell can be used to study the potential effects of microwave electromagnetic fields on biological cells. This modified delivery device allows realtime observation of biological cells during exposure. Microscopic observation is achieved through an aperture in the lower wall of the TEM cell that is sealed with a 700-nm film of the transparent conducting material Indium tin oxide (ITO). To determine the device efficiency, numerical and experimental electromagnetic dosimetry was conducted. For assessing the effect of the aperture on the specific absorption rate (SAR) in the exposed sample, a plastic Petri dish containing cell culture medium, full-wave 3-D electromagnetic simulations and temperature measurements were performed. For 1-W input power, the SAR values obtained at 1.8 GHz in the sample exposed in the TEM cell with the sealed or non-sealed aperture of 20-mm diameter were 1.1 W/kg and 23.6 W/kg, respectively. An excellent homogeneity of the SAR distribution was achieved when the aperture was sealed with the ITO layer. The performance of the delivery system was confirmed by microwave exposure and simultaneous observation of living cells.

In this paper, suppression of mutual coupling is achieved using compact waveguided metamaterials in between elements of a densely packed microstrip array. Both the E-plane internally folded complementary split ring resonator and the H-plane internally folded complementary split ring resonator are employed to reduce the mutual coupling between adjacent elements. Coupling suppression of 18 dB and 9 dB, for elements in the E-plane and H-plane, respectively, is demonstrated. Due to the compact size of the waveguided metamaterials, the edge-to-edge separation between elements is kept at only 0.093λ₀. With the same elements spacing, a 2×2 array is also simulated with compact WG-MTMs. The proposed structure reduces the array size and enables the implementation of compact Multiple-Input-Multiple-Output systems.

In this paper, we present a tri-band electromagnetic absorber with insensitive properties. A rotational symmetry structure with a metallic ground is proposed for the design of the metamaterial absorber. Calculation results show that the absorber has three perfect absorption points at 4.76 GHz, 7.61 GHz and 10.84 GHz with the corresponding absorption rates of 96.7%, 97.8%, and 99.3%. An experiment is given, and the results verify our design. Such a tri-band absorber has the merits of high absorption rate, stable performance with various incident angles and different polarizations.

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.