A planar bandpass filter is proposed in this paper. Its stopband is realized by using the concept of bandstop filter. A key merit of the filter configuration is that the position of the transmission zeros can be conveniently controlled whereas the bandwidth is fixed. The bandpass filter is realized using open circuited uniform impedance resonator and stepped impedance resonators. With five reflection zeros generated in the passband, ten controllable transmission zeros are introduced to sharpen the passband skirts. Skirt selectivity can be freely controlled by tuning the impedance ratio of the stepped impedance resonators. Without coupling gaps between resonators, the structure of the filter is simple and easy to fabricate. To illustrate the concept, a bandpass filter with ten transmission zeros is designed, fabricated and measured. Simulated and measured results are found to be in good agreement with each other, with insertion loss in the passbands less than 1 dB.

An anisotropic dielectric resonator antenna (ADRA) with uniaxial and biaxial permittivity tensors is characterized by using the dielectric waveguide model. An approximate formula for the Q factor of ADRA is derived. Then, it is shown that by certain conditions a wideband ADRA can be designed. Samples of simulation results are shown to demonstrate the capabilities of the proposed anisotropic technique for enhancing the bandwidth of ADRA. The proposed antenna is simulated by two full wave packages, Ansoft HFSS and CST Microwave Studio, and a good agreement is observed among the results.

Tracking multiple maneuvering targets for automotive radar is a vital issue. To this end, a novel DS-UKGMPHD algorithm which combines diagraph switching (DS), unscented Kalman (UK) filter and Gaussian mixture probability hypothesis density (GMPHD) filter is proposed in this paper. The algorithm is capable of tracking a varying number of target cars detected by automotive radar with nonlinear measurement models in a cluttered environment. In addition, variable structure is used to accommodate various target motions in real world. Simulation results demonstrate the superiority of the presented algorithm to IMM-UKGMPHD filter in terms of estimation accuracy of both number and states.

Investigation of a unit cell in terms of reflected wave amplitude and phase, for designing linearly polarized single layer Textile-Reflectarray (TRA) at C-band, is presented. The relative dielectric constant of the material is extracted using resonance method, and a WLAN antenna is designed to verify the accuracy of extracted material parameter. An error of 5% is observed in the extracted dielectric constant, when performance of WLAN antenna is measured at WI-FI Band (2.4 GHz). The extracted dielectric constant is used in the unit cell designing for TRA at the C-Band (5.8 GHz). The radiating element is made using laying technique with conductive thread. A square patch with a ring is selected after analyzing multiple geometries of the patch providing the required reflected phase range and low losses. By varying size of patch and ring of single layer unit cell in CST periodic environment, reflected phase range of 360 degree is achieved, which is required for RA designing. The solid copper ground plane at the bottom of unit cell is replaced with conductive shielded fabric with high level signal attenuation. Four different sizes of textile unit cells are fabricated using conductive thread, and the reflected phase and amplitude are measured using waveguide method. The simulated and measured results are compared when solid copper ground plane at the bottom of unit cell has been replaced with shielded fabric. The proposed method provides the first step towards designing flexible high gain textile reflectarrays.

Filtered backpropagation (FBPP) is a well-known technique used in Diffraction Tomography (DT). For accurate reconstruction of a complex-valued image using FBPP, full 360˚ angular coverage is necessary. However, it has been shown that by exploiting inherent redundancies in the projection data, accurate reconstruction is possible with 270˚ coverage. This is called the minimal-scan angle range. This is done by applying weighting functions (or filters) on projection data of the object to eliminate the redundancies. There could be many general weight functions. These are all equivalent at 270˚ coverage but would perform differently at lower angular coverages and in presence of noise. This paper presents a generalized mathematical framework to generate weight functions for exploiting data redundancy. Further, a comparative analysis of different filters when angular coverage is lower than minimal-scan angle of 270˚ is presented. Simulation studies have been done to find optimum weight filters for sub-minimal angular coverage. The optimum weights generate images comparable to a full 360˚ coverage FBPP reconstruction. Performance of the filters in the presence of noise is also analyzed. These fast and deterministic algorithms are capable of correctly reconstructing complex valued images even at angular coverage of 200˚ while still under the FBPP regime.

Frequency diverse array (FDA) uses a small frequency increment at each antenna element to get a range, angle and time dependent beam pattern. Although linear frequency offset is used in most radar systems, nonlinear frequency offset is also very useful for analyzing FDA radar. A logarithmic frequency offsets based FDA (log-FDA) removes the inherent periodicity of FDA beam pattern to get a single maxima in area of interest. Multiple input multiple output frequency diverse array (MIMO-FDA) radar is also presented recently to provide some improvements compared to FDA radar. In this paper, a new hybrid scheme is proposed in which each subarray of MIMO-FDA uses a variable logarithmic offset. The resultant system, called MIMO-log-FDA, uses not only a different logarithmic offset, but also unique waveform in each subarray. Different logarithmic offsets contributed in terms of getting more control on width of beampattern, while the different waveforms provide diversity, which can be exploited at the receiver of the proposed system. Some improvements in transmit beam patterns have been shown for MIMO-log-FDA, followed by detailed signal model for better estimation of target at the receiving side. Performance analysis is also done in terms of signal to interference plus noise ratio (SINR) and Cramer-Rao lower bound (CRLB). Simulation and results verify the effectiveness of proposed scheme by comparing it with Log-FDA and MIMO-FDA radar.

A new microwave lens antenna suitable for ultra-high frequency (UHF: 300 MHz-3 GHz) band applications is proposed. An improved bow-tie antenna and a planar metamaterial lens design is presented. 5 dB improvement in boresight gain and a directive radiation pattern is achieved with the lens. The application of the designed antenna is demonstrated in a ground penetrating radar (GPR) experiment. The size of the antenna is very compact compared to other antennas found in the literature used for similar applications.

In this paper, two compact multi-layer four-way substrate integrated waveguide (SIW) power combiners/dividers operating at W-band are analyzed and demonstrated experimentally/numerically. Based on the double-layer SIW broadside slot directional coupler, a four-way power combiner/divider is proposed for the first time. And a four-layer four-way SIW power combiner/divider is demonstrated experimentally, by using the transition structure between high-performance multi-layer SIWs and rectangular waveguide. Both SIW power combiners/dividers show the high port-isolation, low loss, high efficiency, wide-band, and small lateral size.

A new improved Least Trimmed Squares (LTS) based algorithm for Non-line-of sight (NLOS) error mitigation is proposed for indoor localisation systems. The conventional LTS algorithm has hard threshold to decide the final set of base stations (BSs) to be used in position calculations. When the number of Line of Sight (LOS) base stations is more than the number of NLOS BSs the conventional LTS algorithm does not include some of them in position estimation due to principle of LTS algorithm or under heavy NLOS environments it cannot separate least biased BSs to use. To improve the performance of the conventional LTS algorithm in dynamic environments we have proposed a method that selects BSs for position calculation based on ordered residuals without discarding half of the BSs. By choosing a set of BSs which have least residual errors among all combinations as a final set for position calculation, we were able to decrease the localisation error of the system in dynamic environments. We demonstrate the robustness of the new improved method based on computer simulations under realistic channel environments.

High reliability and low electromagnetic interference (EMI) are two important factors for many industrial applications such as air based electric transport system charger (AETSC). Therefore, it is essential to introduce high reliability and low EMI power converters. This paper presents a new high reliability and low current ripple DC-DC converter. For the proposed converter, a spectrum analysis approach for suppressing the EMI using chaotic sinusoidal pulse width modulation is provided. In addition, the proposed converter has radio frequency (RF) EMI lower than 100 kHz. However, for higher than 100 kHz, EMI issue of the proposed converter has unsuitable situation.

A lossy filter with resistive coupling is proposed based on substrate integrated waveguide (SIW) resonators, where nonresonating nodes are not required to simplify the realization. The sensitivity analysis of S-parameter to the resistive coupling coefficient is carried out to determine the parameters of coupling structure and mounted resistors. When resistive couplings are added to the structure, the measured 0.2-dB passband bandwidth increases from 198 to 256 MHz, compared with the case without resistive couplings. At a sacrifice on the additional insertion loss of 1.1 dB, the passband flatness and selectivity are improved significantly. The lossy SIW filter can provide a smaller in-band insertion loss than the microstrip counterparts, because the unloaded Q-factor of SIW resonators is higher than that of microstrip resonators. Moreover, a simpler topology and a less insertion loss are obtained in the proposed resistively coupled SIW filter than those of the lossy filter synthesized with lossy coupling matrix. Excellent agreement between the simulated and measured results is achieved to demonstrate our idea.

A new method for reducing the in-band radar cross-section (RCS) of a patch antenna within its operating frequency is presented. This method is based on the utilization of band-pass frequency selective surface (FSS) consisting of non-resonant constituting elements. The main novelty of this method is that it allows for the use of an FSS structure to reducing the in-band RCS of antennas. To validate the proposed method, a low RCS patch antenna resonating at 5 GHz is designed using this method. The simulated results show that the largest RCS reduction is about 15 dB at 5 GHz. A prototype of the proposed antenna is fabricated and tested in an anechoic chamber, and good agreements between the measured and simulated results are demonstrated.

In this paper, an optically transparent (OT) compact 4×4 Butler matrix (BM) operating at 2.4 GHz for Wi-Fi applications is proposed. The device has structured grids refined in quadrilateral cell shapes. The dimensions of cells are chosen based on a simple formulawhich guarantees a minimum required transparency levelin conjunction with a limited rounds of optimizations. A theoretical optical transparency value of 76.2% has been obtained without affecting the excellent electrical performance of the BM. Moreover, complimentary square split ring resonators (CS-SRRs) are patterned in the ground plane of each transparent transmission line in the BM. This loading technique provides a relative size reduction of 16.6% compared to a conventional structure. Simulated and measured results of the proposed design agree well with conventional BM's results. The proposed technique and its related features can be expanded to other microwave devices.

In this paper, two new hybrid excited vernier machines with surface and interior V-shaped PM arrays are proposed. By integrating the vernier structure and field excitation windings together, the proposed machines not only retain the merit of high torque of permanent magnet vernier, but also offer flexible flux adjustment to enable a wide speed range with the introduction of field windings. Different from existing hybrid excited vernier machines having magnets on the rotor, the proposed machines is designed with all excitation sources on the stator. Therefore, temperature rise of magnets of the proposed machines is much easier to control, which in turn reduce the risk of irreversible demagnetization of magnets and enhance the reliability. The electromagnetic performances of the two proposed machines are comprehensively analyzed and quantitatively compared by using the time-stepping finite-element method, verifying the theoretical analysis.

In this paper, a filtering antenna using a dual-mode resonator is presented. The rectangular patch performs not only as a radiator, but also as the last resonator of the bandpass filter. The dual-mode resonator works together with the patch antenna to form a third order bandpass filter with Chebyshev responses. The filtering antenna exhibits good performance, such as skirt selectivity, flat gain within the passband, and high out-of-band suppression.

In low grazing angle scenario, target detection performance is seriously deteriorated due to multipath effect. This paper deals with moving target detection in low grazing angle with orthogonal frequency division multiplexing (OFDM) multi-input multi-output (MIMO) radar. We show that the detection performance can be improved through utilizing the multipath effect. Realistic physical and statistical effects such as refraction of the lower atmosphere and the Earth's curvature are incorporated into the multipath propagation model. Then, we derive a generalized likelihood ratio test (GLRT) detector by taking advantage of the frequency diversity of OFDM and MIMO configuration. Based on the fact that the target responses resonate at different frequencies and statistical characteristics of the test, we propose an algorithm which adaptively allocates the transmitted energy to improve the detection performance. The effectiveness of the GLRT detector as well as the adaptive design method is demonstrated via numerical examples.

In this paper, we report the design and evaluation of a compact 108-element base station antenna array for massive multi-input multi-output (MIMO) system using a 3-port multimode antenna as a unit element. Of these three ports, port 1 and port 2 have orthogonally polarized broadside radiation pattern with measured peak gain of 6.5 dBi and impedance bandwidth of 254 MHz (2.268 GHz-2.522 GHz) and 238 MHz (2.248 GHz-2.486 GHz), respectively, while port 3 has monopole-like radiation pattern having measured peak gain of 1.21 dBi and impedance bandwidth of 102 MHz (2.376 GHz-2.478 GHz). Mutual coupling among all the ports is kept as less than -14 dB. Design of 108 elements massive MIMO antenna array is evaluated as a base station antenna for multiuser urban street grid scenario in MIMO-OFDM downlink system, which is further modeled using Wireless World Initiative New Radio II (WINNER II) Channel models in MATLAB. Parameters like Singular value spread and Dirty Paper Coding (DPC) sum capacity was calculated and compared with i.i.d channel model. For 4 users case using same frequency and time resource, singular value spread and DPC sum capacity for presented antenna array converges to 7 dB and 11.6 bps/Hz at 10 dB SNR, respectively.

A low cost and easy fabrication multilayer antenna for wireless applications was presented to cover the industrial, scientific, and medical ISM band of (5.725-5.875) GHz with a gain of 11.7 dB. The antenna was composed of a feeding patch fabricated on a Rogers RT/Duroid 5880 substrate, and three superstrate layers of Rogers RO3006 were located above the feeding patch at a specific height for each layer. The superstrate layers were added to enhance the bandwidth and gain of the antenna and reduce its side-lobe level and return loss. The simulated and measured results of the operating frequency, return loss, bandwidth, and gain for the antenna were presented. CST Microwave Studio was used in this design's simulation.

As for the lack of the contribution by decision fusion in pose estimation and the demand for the combination of the feature fusion and the decision fusion in SAR ATR, in this paper, with the help of pose estimation, a new multi-look SAR ATR method is proposed in order to improve the performance, which is based on two-level decision fusion of neural network and sparse representation. The first-level decision fusion is acted for the combination of the pose estimation result by neural network and sparse representation. Based on the constraint of pose, these two models are exerted for the multi-look SAR ATR, and the second-level decision fusion is used to achieve the final recognition result. Several experiments based on MSTAR are conducted, and experimental results show that our method can achieve an acceptable result.

Within the framework of the finite-difference time-domain (FDTD) and the weighted Laguerre polynomials (WLPs), we derive an effective update equation of the electromagnetic in the dispersive media by introducing the factorization-splitting (FS) schemes and auxiliary differential equation (ADE). As two examples, we employ a 2-D parallel plate waveguide loaded with two dispersive medium columns and a thin grapheme sheet to calculate the plane wave propagation by using the FS-ADE-WLP-FDTD method. Compared with the ADE-FDTD and the ADE-WLP-FDTD methods, the results from our proposed method show its accuracy and efficiency for dispersive media simulation.