30 GHz Printed Ridge Gap Components and Antennas for Imaging Systems

Working at millimeter waves (MMW) has gained massive attention for wireless communications and imaging systems. For imaging systems, MMW can be used for security to provide good resolution images and detect concealed weapons as it can penetrate common clothes and reflect from the human body and metal objects. Moreover, MMW is safe for human health, contrary to conventional X-ray imaging, which uses an ionized wave. Thus, it has a harmful effect on human health. This research is focusing on building an active wide-view angle millimeter-wave imaging system with a small area of mechanical movement to reduce the data collection time. The imaging system is composed of three main parts: 1) the millimeter-wave components and antennas, 2) the mechanical part for moving the antennas and performing the scan of the imaging area, and 3) the imaging reconstruction algorithm. In order to have an efficient imaging system, the printed ridge gap technology (PRGW) is used to build the imaging system components and antennas. High efficiency coaxial to PRGW transition with a fractional bandwidth of 59.22% at 32.25 GHz is designed to feed the system components. For the transmitting part of the imaging system, a moderate gain PRGW differential feeding planar aperture antenna and a wideband rat-race coupler are designed. The antenna, the rat-race, and the coaxial transition are combined to form the transmitting part, then fabricated and measured. The resulted bandwidth is from 25.62 to 34.34 GHz with a return loss better than 10 dB, a maximum gain of 12.28 dBi, and 3-dB gain bandwidth from 25.62 to 33.77 GHz. For the receiving antenna, a PRGW Butler matrix and its components (directional couplers, 45◦ phase shifters, and crossovers) are designed. A semi-log periodic antenna fed by the PRGW is designed as the radiating element. The PRGW components, the coaxial transition, and the antennas are combined to form the receiving part of the imaging system, which is fabricated and measured. The resulting beam directions are at ±13◦ and ±36◦, at the center frequency (30 GHz). The return loss and the isolations are better than 10 dB over the frequency range from 26.1 to 33.5 GHz. For the imaging reconstruction algorithm, a synthetic aperture radar algorithm is used. Two tests are carried out, one uses CST simulation results, and the other uses measured data from the Concordia antenna chamber lab. The results show an output resolution of 0.6 λ. Finally, the whole imaging system is built with the designed differential feeding antenna as the transmitter, the designed Butler matrix as the receiver, and the synthetic aperture algorithm as the image reconstruction algorithm. The performance network analyzer (PNA) is used to collect the data (s-parameters) required to reconstruct the image, and the antenna range controller system (NSI 5913) is used to mechanically scan the imaging area. The imaging system is used to scan a mannequin carrying an object shaped like a pistol and a knife. The results show that the two objects are detected

Wideband Printed Ridge Gap Rat-Race Coupler for Differential Feeding Antenna

In this paper, a wideband 3 dB hybrid 180° rat-race coupler is introduced in the printed ridge gap waveguide technology. It has simultaneous wide matching and isolation bandwidth with low output amplitude imbalance. It operates in the millimeter wave band from 25.8 to 34.2 GHz (27.96%) with 15 dB return loss and isolation, and ±0.5 dB output amplitude imbalance. The proposed design employing an open stub at the middle of the 3λ/4 branch line and quarter wavelength lines at all the ports of the coupler. The objective of the added open stub is to separate the output ports amplitudes around the -3 dB level by certain values depending on the required amplitude imbalance. The analytical derivation for the role of the added open stub is presented along with a parametric study on its effect on amplitude imbalance, matching, and isolation. This results in having two intersection points for the output ports instead of one of the conventional coupler and hence the amplitude imbalance bandwidth increases. The objective of the added quarter wavelength lines is to improve the matching and isolation bandwidths. First, the conventional rat-race coupler is presented and a bandwidth of 14.25% at 30 GHz is achieved. After that the rat-race with the added quarter wavelength lines is presented to illustrate the objective of the added quarter wavelength lines and a bandwidth of 19.44% is achieved. Finally, the rat-race with the quarter wavelength lines and the added stub is presented and a prototype is fabricated and measured. The s-parameters measurements are in a good agreement with the simulated ones

High Gain and Wideband High Dense Dielectric Patch Antenna Using FSS Superstrate for Millimeter-Wave Applications

Gain and bandwidth enhancement of low profile, linearly polarized square dense dielectric patch antennas using a frequency selective surface (FSS) superstrate layer is proposed. A high dense dielectric patch antenna is utilized as a radiating element instead of a metallic patch in order to gain several significant advantages, including low profile, wide bandwidth, and high radiation efficiency. The implemented antenna is excited by an aperture-coupled feeding technique. The antenna gain is enhanced by using a highly reflective FSS superstrate layer, realizing an antenna gain enhancement of 11 dBi. The implemented antenna acquired a measured gain of about 17.78 dBi at 28 GHz with a 9% bandwidth and radiation efficiency of 90%. The bandwidth of the proposed antenna is improved by using a unit cell printed on two sides, as it provides a positive phase gradient over the desired frequency range. The antenna impedance bandwidth is broadened and the measured impedance matching S11 exhibited a 15.54% instead of 9% bandwidth while maintaining a high-gain characteristic of about 15.4 dBi. The implemented antenna presents a solid radiation performance with good agreement between the measured and simulation results. For some attractive advantages such as low profile, low cost, lightweight, small size, and ease of implementation, the proposed antenna is a very good candidate for millimeter-wave wireless communications

4×4 -Element Cavity Slot Antenna Differentially-Fed by Odd Mode Ridge Gap Waveguide

A differential feeding for a cavity slot antenna is presented. The proposed feeding is based on a simple mechanism rather than the traditional complex networks that suffer from high losses. It is based on exciting the first higher order mode (TE10) of the ridge gap waveguide (RGW) by enlarging the ridge width. This enlargement would excite some undesired even modes that are suppressed by inserting a vertical perfectly electric conducting (PEC) wall in the middle of the waveguide based on the concept of magic tee operation. The proposed 4 × 4 cavity slot antenna is implemented using substrate integrated waveguide (SIW) technology. Two horizontal slots on the top of proposed wide RGW, representing the differential feeding approach, are implemented to feed the cavity slot antenna. The slots couple the fields with same amplitudes and 1800 phase difference to the cavity. The electric fields of the two coupling slots have odd symmetry in the x-axis, and subsequently, uniform electric field distribution of the TE440 mode of a cavity can be excited. The 4/4 radiating slots are etched on the top of the cavity in a specific distribution to ensure having in-phase fields for broadside radiation with low-cross-polarization levels. The measurement and simulation results of the proposed cavity slot antenna are in a good agreement. The obtained results confirm that the proposed antenna achieves a relative bandwidth of 7.1% for -10-dB return loss, a gain of about 16.5 dBi, and a side lobe level about -17 dB in E-plane and -13.8 dB in H-plane. Moreover, the proposed antenna provides low cross-polarization levels (-35 dB in E-plane and -27 dB in H-plane) within the operating frequency band of 32.5 to 34.9 GHz. With this achieved low profile, high gain, and high efficiency of the proposed cavity slot antenna, it may have a great potential for millimeter-wave (MMW) applications

Optimum Wideband High Gain Analog Beamforming Network for 5G Applications

A broadband high-gain millimeter-wave (mmWave) array beamforming network (BFN) design, analysis, and implementation based on the Rotman lens antenna array feeding are presented. The BFN is intended for operation in the (26-40) GHz frequency band for a wide range of potential applications in the fifth generation (5G). The system is made on Rogers substrate, RO6010, to provide compatibility with standard planar low-cost processing techniques for millimeter-wave monolithic integrated circuit (MMIC). The measured results show the system capability of 80° beam scanning for different angles at -39.7°, -26.5°, -13.3°, 0°, +13.3°, +26.5°, and +39.5° at 28 GHz. With these features in addition to being compact size, low profile, and lightweight, this BFN is suitable for various millimeter-wave and 5G applications such as the advanced multi-in multi-out (MIMO) systems, remote sensing, and automotive radar

Analysis and Design of a Wideband Coaxial Transition to Metal and Printed Ridge Gap Waveguide

In this paper, a wideband coaxial to ridge gap transition is proposed and implemented. The transition has a compact size, wide bandwidth, and simple structure. It can be used to excite ridge gap waveguides implemented by the printed circuit board or computer numerical control (CNC) technologies. A similar circuit model for a coax-to-microstrip junction is proposed and used to establish a systematic design procedure for the proposed transition. Perfect electric conductor and perfect magnetic conductor (PMC) boundaries are used to make the procedure independent of the fabrication technology. The PMC is replaced by a bed of nails for ridge gap realized by CNC technology and mushroom-shaped structure in the case of PCB technology. The proposed transition based on the PCB technology is fabricated and measured. There is a good agreement between simulated and measured results which validates the proposed design. The transition has a 59.22% bandwidth with S11−0.5 dB

Ridge Gap Waveguide Beamforming Components and Antennas for Millimeter-Wave Applications

With the improvement of mobile communication technologies and their broad applications, mobile communication will have more impact on our life. Such systems will support a variety of personal communication services with high-data rate and very low latency applications. To achieve such demands, many proposals associated with the development of 5G identify a set of requirements for which different technological directions are independently emerging. One direction is utilizing the millimeter-wave (mm-Wave) frequency bands where more spectrums are available. Millimeter-wave frequencies offer the advantage of physically smaller components that results in cost-effective RF transceivers and feasible large-scale integrated phased arrays. The smart RF transceivers of 5G along with the potential high-frequency innovative designs must satisfy the growing consumer and technology requirements. This implies utilizing the state-of-the-art guiding structures, especially printed ridge gap waveguide (PRGW), that have low loss and minimal dispersion compared with traditional PCB-based structures. The present chapter focuses on the necessary components for a beamforming antenna system which is implemented using PRGW technology. Millimeter wave antennas with different polarizations have been addressed. Power combining and dividing components have been also developed. These components have been used for integration in a complete beamforming antenna system working at an mm-Wave frequency band

IMPACT OF COAGULANTS ON THE TSS SEPARATION PERFORMANCE IN CLEAN WATER PRODUCTION : AN EXPERIMENTAL FINDINGS

This paper reports an experiment conducted with a feed water contained low level total suspended solid (TSS≤ 10 mgL-1 ). This research aims to investigate a problem to justify whether coagulants is required to filter that feed water to produce required clean water (TSS≤ 1.0 mgL-1 ). This research has been conducted with combined use of Multi Media Water Filter (MWF) and Micro Filter (MF). The water filtration rate of this experiment was 20.0 m3(d) -1 . The TSS in product water (PW) was 0.735 mgL-1 when the plant was operated with coagulants. When the plant operated without coagulants the TSS content in PW was 0.876 mgL-1 . Two sets of experimental data were analysed and tested with paired-samples t-test at a 95% confidence level. The result demonstrated that the P-value was more than 0.05 (>0.05) when compared to the mean difference between the data sets. This finding indicates that the TSS content in PW of these two processes is nearly equal, and there is no significant difference between the two processes. This finding could be a reference to the water industry, engineering professionals and policy implementation agencies relating to the use of coagulants in the WF process. This study concludes that coagulants are not required in the WF process when feed water contains TSS less than 10 mgL-1 and the MWF can significantly remove TSS from feed water to produce the required clean water. This study recommends similar further research with various types of feed water to develop a standard model for the WF process to achieve SDG 6, SDG8, and SDG13

The mental health of youth and young adults during the transition to adulthood in Egypt

Background: There has been growing interest in the stalled transition to adulthood in the Middle East and North Africa (MENA) and its consequences for young people's socioeconomic outcomes. However, little is known about how important life transitions relate to youth psychosocial well-being in the region. Objective: Drawing on a life course framework, we estimate the associations between making transitions in education, employment, and marriage with changes in mental health among young people in Egypt. Methods: We descriptively analyze mental health scores, measured via the Self-Reporting Questionnaire-20 and disaggregated by gender, for a panel of young people first surveyed in 2009 at ages 13-29 and followed up in late 2013 and early 2014. We regress change in mental health scores against indicators of making different transitions. Results: Young women experience worse mental health than young men overall. Lower school achievement was associated with poorer mental health; being out of the labor force was an additional risk factor for young men. While average mental health scores improved over time, over a quarter of the sample experienced worsening mental health, related to failure to marry and find a job among older men, and failure to finish schooling among younger women. Conclusions: Mental health is an important but often overlooked component of youth well-being during the transition to adulthood in MENA, and potentially other low- and middle-income countries. Contribution: This is the first paper to empirically examine the relationship between psychosocial well-being and achieving important socioeconomic milestones among a nationally representative cohort of young people in MENA