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.

In this paper, an efficient lightweight double-layer absorber with impedance-matching structure at X-Ku bands was designed, optimized and implemented. First, genetic algorithm (GA) was considered to optimize the thicknesses and material properties for better absorption of the incident electromagnetic wave and reduction of radar cross section (RCS). Next, with the aid of the obtained dielectric and magnetic properties, the microwave absorber was fabricated from magnetodielectric composite materials besides a natural rubber. Finally, the analytical and numerical results were compared with the measurements to check the validity of the design. Experiments showed that the reflection coefficient for each layer backed with a metallic sheet was insufficient; however, for the double layer absorber, the reflectivity measurement values reached up to -28 dB in the case of normal incidence and -17 dB for oblique incidence.

Design and development of a novel dual-band microstrip patch array antenna suitable for WLAN and WiMAX applications are presented. The proposed array configuration is obtained by employing two parasitic patches gap coupled to the driven elements of a single layer proximity fed 2x1 microstrip patch array configuration. The proposed dual-band array has the advantages of enhanced bandwidth and gain. The feed patches are excited by proximity feeding method and the parasitic patches are excited by gap-coupling. This microstrip patch array provides resonances at two frequencies of 2.584 GHz (2.412-2.629 GHz) and 3.508 GHz (3.469-3.541 GHz). This novel configuration has a measured gain of 8.51 dBi and 5.8 dBi in lower and upper bands with an impedance bandwidth of 8.16% and 2.05% respectively. Additionally, to enhance the front to back ratio at the upper resonant frequency, a metal plate is placed at the back side of the array antenna. This modified proximity fed gap coupled array provides directional radiation patterns with improved gains. Re-configurability in the form of beam steering is obtained in the modified array configuration by varying the air gap between the ground plane and metal plate. The simulated results are in good agreement with the experimental ones.

A high-performance microstrip low-pass filter (LPF) with low cutoff frequency, negligible passband insertion loss, very sharp transition band, and deep ultra-wide stopband is designed, fabricated and measured. The presented filter is realized using three types of resonators which are coupled C-shape defected ground structure (C-CDGS), mirrored series-resonant branch loaded by radial stub, and high impedance line loaded by radial stub. A novel equivalent circuit model of the C-CDGS resonator is created, and its corresponding parameters are also extracted. The proposed filter is experimentally verified through the measured results which show good agreement with electromagnetic simulations.

In this paper, a novel broadband equalizer optimization technique is introduced for high-speed digital system designs. Through effectively compensating both conductor loss and dielectric loss, this technique provides a new solution to find optimal equalizer for high-speed signaling over printed circuit board (PCB) with continuous time linear equalizer (CTLE) as an application. The coefficients of CTLE are quickly identified through searching the minimum of the variation of total transfer functions over the low-mid frequency range. Channel simulations with different server interfaces of 12 Gbps and 25 Gbps are performed, respectively. Simulation results are presented to validate the technique.

In this paper, a miniaturized dipole antenna operating at 100 MHz frequency for Ground Penetrating Radar (GPR) application is presented. A conventional dipole antenna length is half of its lowest operating frequency wavelength. As low frequency GPR system is vital for high depth penetration, the size of the antenna used reduces its handling and portability. Therefore, the technique of miniaturizing a dipole antenna by adding extra radiating arms is presented here. The antenna design and analysis is carried out using Advanced Digital System (ADS) software, and a network analyser is used to validate antenna performance. The antenna of 66.5 cm × 22 cm dimension, fabricated on an FR4 substrate exhibits a frequency resonance at 104 MHz with 8 MHz -10 dB bandwidth. The proposed antenna radiates in omnidirectional pattern and features 55 % reduction in length compared to a conventional dipole antenna of same frequency operation.

This paper presents a compact tri-band dual-polarized planar monopole antenna, which is linearly polarized in the lower and middle bands and circularly polarized in the higher band. The antenna is printed on a substrate with an asymmetrical ground plane and a loaded vertical stub. The vertical stub and asymmetrical ground plane are mainly used to make the antenna obtain circular polarization performance in the higher band. The antenna has been built and tested. Its measured 10-dB impedance bandwidths are 2.39-2.54 GHz, 3.38-4.12 GHz, and 4.57-6.04 GHz, which can fully cover all the 2.4/5.2/5.8 GHz WLAN bands, all the 2.4/5.5 GHz Wi-Fi bands, and 3.5/5.5 GHz WiMAX bands. In the higher band, the measured 3-dB axial-ratio bandwidth is 5.4-5.83 GHz.