Azremi Abdullah Al-Hadi

RUBBER TIRE DUST-RICE HUSK PYRAMIDAL MICROWAVE ABSORBER

Rubber tire dust-rice husk is an innovation in improving the design of pyramidal microwave absorbers to be used in radio frequency (RF) anechoic chambers. An RF anechoic chamber is a shielded room covered with absorbers to eliminate unwanted re∞ection signals. To design the pyramidal microwave absorber, rice husk will be added to rubber tire dust since the study shows that both have high percentages of carbon. This innovative material combination will be investigated to determine the best re∞ectivity or re∞ection loss performance of pyramidal microwave absorbers. Carbon is the most important element that must be in the absorber in order to help the absorption of unwanted microwave signals. In the commercial

Measurement of pyramidal microwave absorbers using RCS methods

In this work, a commonly used measurement techniques were used to define the reflection loss performance of pyramidal microwave absorbers mounted on a wall. The technique is namely, Radar Cross Section (RCS) measurement method. Six set of pyramidal microwave absorbers and flat square absorbers were installed at one side wall, in an RF shielded room in order to investigate the performance. Two types of cable losses measurement techniques were applied to compare its performance under different loss conditions. The reflection loss values resulting from this investigation were then analyzed and discussed.

A Review of Antennas for Picosatellite Applications

Cube Satellite (CubeSat) technology is an attractive emerging alternative to conventional satellites in radio astronomy, earth observation, weather forecasting, space research, and communications. Its size, however, poses a more challenging restriction on the circuitry and components as they are expected to be closely spaced and very power efficient. One of the main components that will require careful design for CubeSats is their antennas, as they are needed to be lightweight, small in size, and compact or deployable for larger antennas. This paper presents a review of antennas suitable for picosatellite applications. An overview of the applications of picosatellites will first be explained, prior to a discussion on their antenna requirements. Material and antenna topologies which have been used will be subsequently discussed prior to the presentation of several deployable configurations. Finally, a perspective and future research work on CubeSat antennas will be discussed in the conclusion.

Revolutionizing Wearables for 5G: 5G Technologies: Recent Developments and Future Perspectives for Wearable Devices and Antennas

Wearable devices present an increasingly attractive solution for numerous applications in sectors ranging from the military to medicine to consumer electronics. They will also play an integral role in the imminent fifth-generation (5G) networks, which are expected to operate with higher bit rates and lower outage probabilities in smaller microcells and picocells covering broader areas than fourth-generation (4G) or older technologies. In addition, beam reconfigurability and beamforming are expected to facilitate spectral and energy efficiencies at both the mobile device and base station levels. In overcoming the limitations of current 4G systems, the new features and capabilities envisioned for 5G networks will radically change applications in transportation, health care, smart homes, and wireless robots, among many others [1], [2].

Advantages and Challenges of 10-Gbps Transmission on High-Density Interconnect Boards

This paper provides a brief introduction to high-density interconnect (HDI) technology and its implementation on printed circuit boards (PCBs). The advantages and challenges of implementing 10-Gbps signal transmission on high-density interconnect boards are discussed in detail. The advantages (e.g., smaller via dimension and via stub removal) and challenges (e.g., crosstalk due to smaller interpair separation) of HDI are studied by analyzing the S-parameter, time-domain reflectometry (TDR), and transmission-line eye diagrams obtained by three-dimensional electromagnetic modeling (3DEM) and two-dimensional electromagnetic modeling (2DEM) using Mentor Graphics HyperLynx and Keysight Advanced Design System (ADS) electronic computer-aided design (ECAD) software. HDI outperforms conventional PCB technology in terms of signal integrity, but proper routing topology should be applied to overcome the challenge posed by crosstalk due to the tight spacing between traces.

Scattering parameter based loss characteristics of two monopole antennas for low-band LTE mobile terminals

In this paper, the loss exhibited by two monopole antennas on a small terminal chassis is investigated. These two vertical quarter-wavelength monopole antennas were designed to operate at 698 - 960 MHz low-band Long-Term Evolution (LTE) and the loss performance was studied numerically at five different locations. The influence of bandwidth characteristics on the loss was also investigated by tuning the impedance bandwidth of the antennas using a matching circuit. This provides narrow-band and wide-band antenna characteristics using the same multiple antenna structure. Results show that the loss of both wide-band and narrow-band antennas located at the center of the terminal chassis are of at least 30% and 7% lower than the loss of antennas at the edges, respectively. It is also shown that when one of the antenna elements is perpendicularly oriented to the other antenna element, the loss can be reduced by up to 56%. On average, wide-band antennas attained lower loss compared to narrow-band antennas over the matched operational bandwidth.

Impact of non-perfect reference plane on multi-gigabit transmission

Purpose This paper aims to analyze the impact of non-perfect reference plane on the integrity of microstrip differential signals at multi-gigabit transmission on a printed circuit board (PCB). The effects of non-perfect reference contributed by signal crossing over split plane such as impedance discontinuity and crosstalk are investigated by performing analysis in two phases. Design/methodology/approach The first phase involves three-dimensional electromagnetic modeling extraction using Keysight EMPro software. Meanwhile, the second phase involves the import of model extracted from EMPro into simulation using Keysight Advanced Design System that covers insertion loss, return loss, crosstalk, time domain reflectometry and eye diagram. Findings A non-perfect reference plane has a negative impact on signal reflection, attenuation and crosstalk. The analysis results are presented and discussed in detail in the later section of this paper. Originality/value The work that studied the impact of the width and the amount of gaps due to crossing of split planes being experienced on the signal integrity was performed by other researchers. Meanwhile, this paper focused on the impact of length and depth of the gap on signal integrity. These research papers serve as a reference guide for high-speed PCB layout design.

Helical Antenna sensor for Different Liquid Type Identification

There are variety of lliquid sensor measurement systems that available in the market nowadays. It is used to measure various parameter for wide range application or to address a specific application. However, most of the existing monitoring system still involved bulky equipment and required a quite amount or liquid to be tested. The results obtained time consuming and take a long time to obtain the desired results. To solve the problems, we develop and design a small sensor using antenna that is small, robust as well as reliable and efficient to work as a sensor for liquid sensor detection. It is efficient and reliable to obtain in-situ result. The helical antenna is design using CST Software and the fabricated antenna is measured. The helical antenna works on 2 GHz frequency is tested with three different type of liquids and it is shows different liquid has their own frequency shift.

Wideband textile antenna with low back radiation for wearable applications

A wideband textile planar antenna operating between the frequency of 2.06 GHz and 2.8 GHz based on the microstrip topology is presented. The antenna features a low back-radiation due to the existence of the full rear ground plane in the chosen microstrip topology. The intrinsic narrowband behavior of this topology is alleviated by the combination of several broadbanding techniques. The antenna indicated satisfactory performance in terms of reflection coefficients, gain/directivity and radiation patterns.

A C-slotted dual band textile antenna for WBAN applications

A dual band C-shaped slotted textile antenna with artificial magnetic conductor (AMC) is investigated in this paper. The proposed antenna is operates in the 2.45 GHz (lower) frequency band for WBAN applications and in the 5.8 GHz (upper) frequency band for WLAN applications. A diamond-shaped AMC is used to improve the antenna performance and reduce backwards radiation for on-body usage. The proposed antenna is fully fabricated using textiles and utilizes felt as its substrate and ShieldIt Super as its conducting elements. Simulations and comparison against a same antenna without the AMC plane indicated that this conformal antenna operates with good reflection coefficients, gains, and radiation pattern within the desired bands.