The block diagram of a TR (Transmit Receive) module that consists of four channels using a silicon substrate is presented in this paper. The silicon substrate fabricated by microelectronic process has been adopted to increase the interconnect density of module. Several broadband vertical transitions are simulated and optimized by EM simulator. The vertical transition works well from DC to 40 GHz. The insertion loss is less than 1 dB, and the return loss is better than -15 dB in back-to-back configuration. A novel TR module based on the silicon substrate is proposed for its miniaturization and high integration advantages. The module occupies a compact area of 30 mm×20 mm×1.8 mm, and the weight is 1.77 g.

This paper reviews the motion of a charged particle in the electrostatic field of two coaxial likely charged rings located at some distance from one another. The charges of rings and that of the particle are of the same sign. Initial conditions of motion of the particle relatively to the rings under which the particle overcomes the electrostatic repulsion of rings and localises along a particular circular trajectory laying in the internal space between the rings were determined.

In this paper, a channel characterization of an RF link using circularly polarized antennas inside a mine is performed. The association of circular polarization with multiple-input-multiple-output (MIMO) radio technologies represents a powerful tool to improve the performance of an underground RF channel. The statistical parameters of the channel are derived from in-mine measurements at the 2.4 GHz band for both co-polarization (CP) and cross-polarization (XP) scenarios. Results show a remarkable improvement through the use of MIMO combined with circular polarization compared to the regular patch MIMO antenna system, in terms of channel capacity and path loss. This improvement increases significantly at the XP scenarios, reaching up to 18 bps/Hz for channel capacity and up to 21 dB for path loss. The RMS delay spread for a circularly polarized setup is generally higher than the linearly polarized MIMO patch setup due to surface roughness of the gallery. In the linear polarization case, a signal degradation of more than 15 dB at the XP case is observed compared to the CP scenario. This signal loss that is due to depolarization is somewhat mitigated by the surface roughness.Due to its superior and stable performance, MIMO combined with circular polarization is better suited than a regular MIMO patch system for in-mine uses, especially in the applications where the transmitter may change direction with respect to the receiver.

Carbon fiber reinforced polymer (CFRP) is measured as reflector material for millimeter waves at 60 GHz. Reflectivity is measured to characterize material anisotropy in a mono-static setup. Disc shaped material samples are rotated in steps of one degree. Four commonly employed CFRP are investigated: unidirectional fibers, plain-weave, twill-weave and fiber shreds. Results show that the unidirectional CFRP and twill-weave CFRP are anisotropic, while the remaining materials are isotropic within measurement accuracy.

In this paper, a beam switchable antenna solution for vehicular use is presented. Main objective is to improve the cellular connectivity of vehicles operating in poor coverage region. An adaptive antenna system operating in the frequency band 824-960 MHz having high gain, and full azimuth plane coverage, and main beam in elevation plane pointing towards 90˚, was developed. Beam switchable antenna provides beam-steering in azimuth plane, by switching one antenna element active at a time. The concept of stacked patch antenna with L probe feed was used for a single element. This arrangement gives gain of 7.4-8.2 dBi, and total radiation eciency of 0.11 dB, over the band, with broadside radiation pattern, and half power beam width of single element up to 80˚. The field measurements for the designed antenna system were performed in poor coverage regions using commercial cellular network. Results were compared to corresponding results of conventional vehicular antenna, having omnidirectional radiation pattern and the gain of 3 dBi. The developed antenna system results in 3.5...12.7 dB higher RX level than reference antenna and increase communication range from 71 km to 109 km in open area. Similarly, in suburban area the communication range is increased from 20 km to 30.8 km. Also, the narrower beam acts as spatial filter and results in reduced fading.

This paper presents the applicability of cavity modeling technique to analyze field propagation inside a multiport waveguide network. For a better understanding of the subject, we have considered a five-port quadraplexer as our target network. Field propagations within the network at different passband and stopband frequencies have been presented. The analysis has been verified by comparing the overall frequency response of the network with the available data in literature. The analysis demonstrates the field division at different junctions as well as field attenuation/propagation at different points of the network, which will be helpful for designing more complex and/or advanced multiport waveguide networks. It also demonstrates the presence of higher order modes at different discontinuities of the network and their effectson the respective field distributions.

A three-section branch-line coupler is miniaturized using diamond-series stubs microstrip lines. The modified coupler is capable of operating from 1.6 GHz to 3 GHz with a return loss of less than -20 dB, phase imbalance of less than 2.5°, insertion loss and coupling of 4.5 dB and 3.02 dB, respectively. The bandwidth of the coupler has been extended up to 1.4 GHz. In addition, it achieves up to 84% size reduction as compared to a conventional three-section coupler. Furthermore, its performance and circuit size were compared with another modified coupler with normal open-stubs microstrip lines. Effects of the diamond structure and number of stubs were analyzed and discussed in detail, Furthermore, the results achieved by this study are superior to the previous studies.

A new single-layer element structure for broadband operation is presented. The element is composed of a circular ring attached two sets of phase-delay lines with the opposite direction of rotation. The demission of circular ring is fixed, and about 460° reflection phase range is achieved by varying the length of the phase-delay lines. Using the proposed element, a 381-element single-layer linearly polarized reflectarray is designed, fabricated and measured. A gain of 27.5 dB is measured at 13.58 GHz with 3-dB beamwidth of about 6.8°, and the corresponding aperture efficiency is 57.3%. Good radiation performances are also achieved at other frequencies. Measured results show 1.5-dB and 3-dB gain bandwidth of 47.8% (13.58-20.08 GHz) and 64% (12.08-20.78 GHz) with the center frequency of 13.58 GHz respectively, which demonstrates excellent broadband performance. Besides, high aperture efficiencies (more than 50%) are achieved in a wide frequency range (12.08-17.08 GHz). Low cross polarization and sidelobe levels are also achieved in the frequency band.

A process is introduced to design and validate insertable rectangular-waveguide verification standards for the electromagnetic characterization of materials using the Nicolson-Ross-Weir method. Each insertable structure consists of a series of metal steps that acts as a surrogate material exhibiting smooth and predictable permittivity and permeability characteristics across the waveguide band. These known material properties can be used to assess the performance of material characterization systems. Since the verification standards are inserted into the waveguide in the same manner as samples under test, each step in the normal measurement procedure is duplicated. A specific example of an S-band verification standard is presented, with the standard fabricated using two different methods. The first standard is machined from a solid metal block while the second is constructed by metalizing a 3-D printed polymer structure. Comparison of the predicted material parameters to those extracted from experimental data demonstrates the utility of the proposed insertable standards.

A front-end module (FEM) consisting of a single-pole-double-throw (SPDT) switch and a low noise amplifier (LNA) with good performance is proposed. The SPDT switch is based on PIN diodes, which are mounted on impedance transforming lines parallelled to the main transmission lines with an asymmetric topology. This asymmetric topology is utilized to achieve low insertion loss and high transmit-to-receive isolation. The interstage matching of switch and LNA is designed to achieve low noise figure. To validate the design, the FEM is simulated, fabricated and measured. The experiment results show that, within the range of 7.8-8.1 GHz, the FEM achieves a gain of 22 dB and noise figure of 1.9 dB in receiving mode, with an insertion loss of 0.9 dB and isolation of 40 dB in transmitting mode. In addition, the FEM can handle up to 4 W transmitting power at 8 GHz with good linearity.

A new direction finding method for multiple-input multiple-output (MIMO) radar with non-circular sources is proposed. The method takes advantage of the properties of non-circular sources to formulate a new virtual array. Then based on the ESPRIT like algorithm, the bearing of targets is estimated. In addition, the direction of departure (DOD) and direction of arrival (DOA) are paired automatically. Compared with the uniform circular array estimation of signal parameters by rotational invariance techniques (UCA-ESPRIT), the proposed method achieves better estimation performance and can deal with more sources. We also provide the Cramer-Rao Lower Bound (CRLB) for comparison. Simulation results demonstrate the effectiveness and feasibility of the proposed method.

Aircraft collision avoidance system is an airborne system which is designed to provide the service as a last defense equipment for avoiding mid-air collisions between aircraft. End-fired antenna is suitable to be used in such airborne systems where low aerodynamic drag is urgently required. An effort to develop such an antenna using dipole elements is presented in this paper. Here a unit element planar folded dipole antenna is presented which radiates in the end-fire direction. Split ring resonators inspired artificial materials are incorporated in the design to improve the directivity performance of the proposed antenna, and those materials are loaded in the same plane of the primary dipole radiator. Here suppression of surface wave in the antenna takes place, which results in gain enhancement and also reduction of side lobes which make radiation pattern better. All these proposed antennas are designed and simulated in CST Microwave Studio (MWS) EM tool which is based on time domain solver. The performance and other antenna characteristics have been explored from the simulation results followed by the antenna fabrication and measurement. Quite good agreement is achieved between the simulated and measured results. Much better performance characteristics make this proposed antenna a good candidate for this application.

Predicting signal power loss between the transmitter and receiver with minimal error is an important issue in telecommunication network planning and optimization process. In recent years, median order statistic filters have been exploited as a preprocessing constituent for analyzing signals. This work presents a resourceful predictive model, built on multi-layer perceptron (MLP) network with vector order statistic filter based preprocessing technique for improved prediction of measured signal power loss in a microcellular LTE network environment. The predictive model is termed Vector statistic filters multilayer perceptron (VSF-MLP). In terms of some essential performance evaluation indices such as the correlation coefficient, root-mean-square error and coefficient of efficiency, results show that VSF-MLP model prediction performs considerably better than the standard MLP model prediction approach on signal power data collected from different study locations in typical urban terrain.

Due to changes in global security requirements attention is turning to new means by which anomalies on the human body might be identified. For security screening systems operating in the millimeter wave band anomalies can be identified by measuring the emissivities of subjects. As the interaction of millimeter waves with the human body is only a fraction of a millimeter into the skin and clothing has a small, but known effect, precise measurement of the emission and reflection of this radiation will allow comparisons with the norm for that region of the body and person category. A technique to measure the human skin emissivity in vivo over the frequency band 80 GHz to 100 GHz is developed and described. The mean emissivity values of the skin of a sample of 60 healthy participants (36 males and 24 females) measured using a 90 GHz calibrated radiometer was found to range from 0.17±0.005 to 0.68±0.005. The lower values of emissivity are a result of measuring particularly thin skin on the inner wrist, volar side of the forearm, and back of hand, whereas higher values of emissivity are results of measuring thick skin on the outer wrist, dorsal surface of the forearm, and palm of hand. The mean differences in the emissivity between Asian and European male participants were calculated to be in the range of 0.04 to 0.11 over all measurement locations. Experimental measurements of the emissivity for male and female participants having normal and high body mass index indicate that the mean differences in the emissivity are in the range of 0.05 to 0.15 for all measurement locations. These results show the quantitative variations in the skin emissivity between locations, gender, and individuals. The mean differences in the emissivity values between dry and wet skin on the palm of hand and back of hand regions were found to be 0.143 and 0.066 respectively. These results confirm that radiometry can, as a non-contact method, identify surfaces attached to the human skin in tens of seconds. These results indicate a route to machine anomaly detection that may increase the through-put speed, the detection probabilities and reduce the false alarm rates in security screening portals.

In this work, a new technique in suppressing the effect of four-wave mixing (FWM) by Odd-Even Channels Arrangement (OEC) is presented. The proposed technique is verified mathematically and by simulations with other recent techniques which are input power and channel spacing under the same input parameters. Simulation was done with the power variation effect, and the bit rate was 100 Gb\s. Based on theoretical and simulation analyses, FWM power was drastically reduced by more than 10 dB when OEC was conducted. In terms of system performance, OEC offered better performance than previous techniques in both theoretical and simulation analyses.

Sparse regularization imaging method (SRIM) is an effective approach to implement azimuth super-resolution for forward-looking scanning radar. However, for the scene that contains adjacent strong targets in the continuous weak background, SRIM may destroy the structure of the scene when trying to separate the closely located targets. In this paper, a divide and conquer regularization imaging method (DC-RIM) is proposed to solve this problem. Firstly, the data are divided into two channels by the mean-variance segmentation method. Normally, we consider that the data of channel I contain strong scatterers and that the data of channel II contain weak background. Afterwards, SRIM is conducted on channel I to distinguish the targets. For the data of channel II, a region enhancement regularization method is particularly proposed to acquire a good structure of the scene by making use of two-order gradient information of the data. Finally, a good imaging result can be obtained by combining the results of two channels. Experiments based on both synthetic and real data are given to verify the effectiveness of the method.

In this paper, two compact planar substrate integrated waveguide (SIW) cavity-backed antennas are proposed for wireless local area network (WLAN) at 5.5 GHz and wireless body area network (WBAN) at 5.8 GHz. The miniaturization is achieved with the concept of quarter-mode-topology, and the size of the cavity is reduced up to one-fourth of the circular SIW cavity. A L-shaped slot is etched on the top plane for miniaturization, and antenna-1 is realized which resonates at 5.5 GHz. A metal strip has been added in the middle section of the slot, and antenna-2 is realized, which resonates at 5.8 GHz. Both proposed antennas are tested in free space, while the performance of antenna-2 is investigated for on-body condition. In free space, the measured impedance bandwidths of the antenna are 160 MHz and 210 MHz at 5.5 GHz and 5.8 GHz, respectively. The radiation efficiency of the antenna is 89.4% in free space and 57% on phantom at 5.8 GHz. Both measured and simulated results are observed, and they are in a good agreement.

This paper describes an experimental study of passive intermodulation due to metal-tometal contacts with focus on shape influence. This study investigates PIM value of different contact geometric profiles and different contact areas versus normal forces. A complete description of profiles used is done to achieve a relationship between PIM level and contact shape.

This paper discusses the torque constant density in different types of Double Stator Permanent Magnet Brushless DC Motor (DSPM) which are designed for portable applications. It should have high torque constant density so that it will have higher torque as well as lightweight. Previously, there have been many DSPM motor designs that only focus on increasing the torque constant and torque density. However, it is unclear which DSPM motor is the best since the torque constant and torque density are different parameters. Torque constant density will include the torque, volume and current of the motor. The objective of this research is to analyze different types of DSPM motors including the proposed Slotted Rotor DSPM motor (DSPM-SR) which produces higher torque constant density. Besides that, this paper also describes in detail the torque constant density from an electromagnetic point of view. Finite Element Analysis (FEA) and analytical calculation are used to simulate the characteristic of various double stators. The result shows that DSPM-SR has 90.5% higher back electromotive force (emf) and 87.5% higher torque than DSPM-ST. Besides that, the DSPM-SR topology has higher torque constant density about 67.27% than other DSPM motors. As a conclusion, this paper provides the overview and comparison of torque constant densities of various DSPM motors.

Present paper describes the design, development and evaluation of a wideband, compact Ku-band orthomode transducer (OMT) for SATCOM application. It consists of a square waveguide output section, square waveguide to rectangular waveguide transition, straight waveguide port and an orthogonally coupled port. A tapered waveguide section has been used to couple the orthogonal RF (Radio Frequency) signal to the common port. The designed OMT has a transmit port with frequency band 13.75 GHz-14.5 GHz and a receive port with frequency band 10.95-12.5 GHz. Finite element method based ANSYS's High Frequency Structure Simulator (HFSS) EM software has been used for simulation and optimization of OMT. Measured reflection coefficients of OMT over transmission and reception frequency bands are better than -15 dB and -12 dB, respectively. Designed OMT has port to port isolation better than 45 dB against 30 dB isolation of conventional OMT available in market.