A Wideband High-Gain Circularly-Polarized Dielectric Horn Antenna Equipped With Lamé-Axicon Stacked-Disk Lens for Remote Sensing, Air Traffic Control and Satellite Communications

A wideband high-gain circularly polarized (CP) shaped dielectric horn-lens antenna (SDHLA) operating in the frequency band between 6.7 and 18.2 GHz [fractional impedance bandwidth (FIBW) of 92.4%] with a 3-dB axial-ratio in the frequency range from 8.1 to 16.3 GHz [fractional axial-ratio bandwidth (FARBW) of 67.2%], is presented. The antenna, composed of a suitably shaped dielectric horn, integrated with a super-ellipsoidal-axicon dielectric lens made out of stacked thin dielectric disks, is mounted on a printed circuit board (PCB) where a microstrip line terminated with a wideband radial stub is used to excite a S-shaped slot through which the circular polarization is achieved. Parameterized 3D Lamé curves, describing the horn and lens profile, are used to optimize the antenna design. The antenna features a peak realized gain exceeding 13.1 dBi that is beneficial in a variety of applications, such as digital video broadcasting (DVB), remote sensing, weather monitoring, satellite communications, and air traffic control. The full-wave electromagnetic solver CST Studio Suite™, based on a locally conformal finite integration technique (FIT), was employed to design and characterize the antenna whose performances were found to be in good agreement with the experimental measurements.</p

Broadband dielectric resonator antennas for WLAN applications

Today's communications systems require use of broadband antennas to meet high capacity requirements. Furthermore, some applications require smaller antenna sizes. In this work, a broadband Dielectric Resonator Antenna (DRA) for WLAN applications is presented. The antennas presented are compact in size, have the broadside radiation patterns and high radiation efficiency. The bandwidth of the DRA depends on the dielectric material, its shape, as well as the excitation technique used to feed the antenna. The three antennas presented in this thesis are of half cylindrical shape, mounted on ground planes and excited by aperture coupling slot. A parasitic U slot is part of the feeding network for more coupling and bandwidth enhancement. The antennas have good radiation characteristics and operate over a wide band of frequencies. Ansoft HFSS is used for the antenna simulation. CST Microwave studio is also used to compare the accuracy of time domain and frequency domain analysis of the DRAs. The DR material is Rogers RO3010 (TM) with [varepsilon] r = 10.2, and a dielectric loss tangent of 0.0035. The substrate material is Rogers RT/Duroid 5880 (TM) with [varepsilon] s =2.2, a loss tangent of 0.0009, and 0.767 mm thickness. The half-cylindrical DRA is used to have the TEo13 mode excited. The radiation patterns of the three antennas are similar to that of a magnetic monopole which has the broadside radiation pattern. Parasitic U-shaped slots are used with the three presented antennas to enhance the bandwidth by exciting a dual resonant frequency in the TE 01e mode. These slots have similar radiation characteristics to those of the half cylindrical DRAs so the overall radiation patterns of these antennas are not deteriorated. For the fabricated antennas, they have broadside radiation characteristics in H and E planes. As for the impedance bandwidth, the half cylindrical ORA has 24 % fractional bandwidth. For the half cylindrical ORA backed with a rectangular dielectric resonator, 32% bandwidth is achieved. A bandwidth of29% is achieved in the case of half volume Elliptical ORA. The gain of the three antennas slightly changes around 5 dBi which is good for the WLAN applications

Design and Analysis of Dielectric Resonator Antennas For WLAN Applications

The increasing use of wireless mobile communication systems demand the antennas for different systems and standards with properties like reduced size, broadband, multi band operation, moderate gain etc. The planar and dielectric resonator antennas are the present day antenna designer’s choice. However, micro strip and Dielectric resonator antennas inherently have a narrow bandwidth. Since the Federal Communications Commission (FCC) first approved rules for the commercial use of ultra-wideband (UWB) in 2002, the experiments on ultra wide band (UWB) systems have been expanding rapidly. In this thesis, a low-cost compact microstrip line-fed antenna with parasitic patches resulting a Ultra-Wideband characteristics with a band dispensation is presented. The antenna was implemented on FR4 substrate with a thickness of 1.6mm & relative permittivity (µr) of 4.3 .It has a partial ground plane .The antennas is exited by microstrip line feed. The proposed antenna is a Rectangular shape , “T” shape,& “ð” shape made of Teflon of permittivity (µr) of 2.1& compare with “ð” shape made of Roger of permittivity (µr) of 10.2 .The proposed antenna is simulated with CST Studio 2011. The return loss results and radiation pattern plots of the antenna are included in this thesis

ANALYSIS AND DESIGN OF ANTENNA PROBES FOR DETECTION / IMAGING APPLICATIONS

Analysis and Design of Antenna Probes for Detection / Imaging Applications Ayman Elboushi, Ph.D. Concordia University. As a result of increasing international terrorist threats, the need for an efficient inspecting tool has become urgent. Not only for seeing through wall applications, but also to be employed as a safe human body scanner at public places such as airports and borders. The usage of microwave and millimeter wave antennas and systems for detection / imaging applications is currently of increasing research interest targeting the enhancement of different security systems. There are many challenges facing researchers in order to develop such systems. One of the challenges is the proper design of a low cost, reduced size and efficient antenna probe to work as a scanning sensor. In this thesis, two different technology choices of antenna probes for the feasibility of constructing detection / imaging systems are investigated. The first one covers the Ultra Wide Band (UWB) range (3.1 GHz to 10.6 GHz), while the second operates over the Millimeter-Wave (MMW) range. In addition to the development of several antenna probes, two detection / imaging systems are demonstrated and showed reasonably accurate detection results. Three different UWB monopole antenna prototypes, with different radiator shapes (circular, crescent and elliptical) have been introduced. These antennas are designed using a standard printed circuit board (PCB) process to work as probing sensors in a proposed UWB detection / imaging system. In order to enhance the resolution and the detection accuracy of the probe, 4-element Balanced Antipodal Vivaldi Antenna (BAVA) array fed by 1-to-4 UWB modified Wilkinson power divider has been developed. Some successful experiments have been conducted using the proposed UWB detection / imaging system combined with the fabricated antenna probes to detect the presence of a gap between two walls made of different material types, to evaluate the gap width and to estimate the size and exact location of a hidden target between the walls. The second research theme of this thesis is to develop small-sized, light-weight and high gain MMW scanning antenna probes. For the realization of such probes, several gain enhancement techniques have been adopted, including hybridization and a multi-element array principle. Several high-gain hybrid antennas have been designed, fabricated and tested. For demonstration purposes, experiments have been carried out for detecting and imaging a small metallic coin under the jeans layer of a three-layer target emulating a human body’s covering layers. A performance comparison between a standard metallic MMW horn and hybrid microstrip patch/conical horn antenna has been made. The proposed reduced size antenna sensor shows increased efficiency compared with the bulky horn antenna. Resolution enhancement of the reconstructed image of the hidden target is implemented using a new triple-antenna MMW sensor. The triple-antenna sensor consists of three adjacent microstrip patch / conical horn antennas separated by 1.5 wavelengths at the center frequency for coupling reduction between these elements. The middle element of the sensor is used for monitoring the time domain back-reflected signal from the target under inspection, while the side elements are used for monitoring the scattered signals. By the aid of a special signal processing algorithm, an enhanced image of the concealed object can be obtained by combining the three readings of each point in the area under study. The proposed system shows a great ability for detecting a hidden target and enhances the reconstructed image resolution

Advanced Radio Frequency Antennas for Modern Communication and Medical Systems

The main objective of this book is to present novel radio frequency (RF) antennas for 5G, IOT, and medical applications. The book is divided into four sections that present the main topics of radio frequency antennas. The rapid growth in development of cellular wireless communication systems over the last twenty years has resulted in most of world population owning smartphones, smart watches, I-pads, and other RF communication devices. Efficient compact wideband antennas are crucial in RF communication devices. This book presents information on planar antennas, cavity antennas, Vivaldi antennas, phased arrays, MIMO antennas, beamforming phased array reconfigurable Pabry-Perot cavity antennas, and time modulated linear array

Investigation and Design of Different Antennas in Solar Cells' Environments with Their Needed Tools

With the spread use of solar cells as a renewable energy source and the wide use of wireless communications, it is interesting to use the solar cell panels as an energy source for rural wireless communications for security and safety. For compactness, it is proposed to embed antennas in the solar cell panels. Therefore, it is proposed to investigate the antenna characteristics within this environment. As such, the characteristics of the solar cells in the radio frequency region should be studied for proper design of the antennas in such an environment. Therefore, a rigorous design approach for antennas in the solar cells' environment is proposed through this work. A practical model of the solar cells in the microwave frequency range is presented using anisotropic surface impedance boundaries. Two different surface impedance measurement setups are exploited to accurately model solar cells. Moreover, measurements of antennas' radiation efficiency are invoked in this work using the Wheeler cap concept in a contactless fashion to perform measurements within solar cells' environments. A novel measurement technique has been proposed extending conventional Wheeler cap capabilities to measure wide band antennas. The technique promotes a straightforward processing procedure and convenient measurement setup. In addition, a simple, fast, and efficient numerical solution for the electromagnetic scattering arbitrary problems is proposed. Based on the uniqueness theorem and the use of novel equivalent problems with Random Auxiliary Sources (\emph{RAS}), more degrees of freedom are added resulting in significantly faster solutions. The proposed technique is expected to provide a significant reduction in the execution time and memory requirements compared to the surface equivalent based Method of Moments (MoM) as the inherent properties of this procedure are used. Various verification and result cases are presented to assess the introduced technique, which is incorporated into different analysis and design problems in this work. Moreover, the RAS method is extended to model antennas in their radiating and scattering modes, which, in turns, is adopted in the reflectarray antenna analysis and design procedures. The introduced solar cells models along with the developed computations and measurement tools are used to develop a design procedure for antennas suited for the solar cells environment. An optically transparent reflectarray antenna integrated with solar cells is proposed as an application of interest that suits satellite communication purposes. Material choice, feed antenna tailored design and rigorous design procedures are presented to enhance the achievable performance of the antenna/solar cells integrated device

Developing Novel 3D Antennas Using Advanced Additive Manufacturing Technology

In today’s world of wireless communication systems, antenna engineering is rapidly advancing as the wireless services continue to expand in support of emerging commercial applications. Antennas play a key role in the performance of advanced transceiver systems where they serve to convert electric power to electromagnetic waves and vice versa. Researchers have held significant interest in developing this crucial component for wireless communication systems by employing a variety of design techniques. In the past few years, demands for electrically small antennas continues to increase, particularly among portable and mobile wireless devices, medical electronics and aerospace systems. This trend toward smaller electronic devices makes the three dimensional (3D) antennas very appealing, since they can be designed in a way to use every available space inside the devise. Additive Manufacturing (AM) method could help to find great solutions for the antennas design for next generation of wireless communication systems. In this thesis, the design and fabrication of 3D printed antennas using AM technology is studied. To demonstrate this application of AM, different types of antennas structures have been designed and fabricated using various manufacturing processes. This thesis studies, for the first time, embedded conductive 3D printed antennas using PolyLactic Acid (PLA) and Acrylonitrile Butadiene Styrene (ABS) for substrate parts and high temperature carbon paste for conductive parts which can be a good candidate to overcome the limitations of direct printing on 3D surfaces that is the most popular method to fabricate conductive parts of the antennas. This thesis also studies, for the first time, the fabrication of antennas with 3D printed conductive parts which can contribute to the new generation of 3D printed antennas