Millimeter-Wave Components and Antennas for Spatial and Polarization Diversity using PRGW Technology

The evolution of the wireless communication systems to the future generation is accompanied by a huge improvement in the system performance through providing a high data rate with low latency. These systems require access to millimeter wave (mmWave) bands, which offer several advantages such as physically smaller components and much wider bandwidthcomparedtomicrowavefrequencies. However, mmWavecomponentsstillneed a significant improvement to follow the rapid variations in future technologies. Although mmWave frequencies can carry more data, they are limited in terms of their penetration capabilities and their coverage range. Moreover, these frequencies avoid deploying traditional guiding technologies such as microstrip lines due to high radiation and material losses. Hence, utilizing new guiding structure techniques such as Printed Ridge Gap Waveguide (PRGW) is essential in future mmWave systems implementation. ThemainpurposeofthisthesisistodesignmmWavecomponents,antennasubsystems and utilize both in beam switching systems. The major mmWave components addressed in this thesis are hybrid coupler, crossover, and differential power divider where the host guidingstructureisthePRGW.Inaddition,variousdesignsfordifferentialfeedingPRGW antennas and antenna arrays are presented featuring wide bandwidth and high gain in mmWave band. Moreover, the integration of both the proposed components and the featured antennas is introduced. This can be considered as a significant step toward the requirements fulfillment of today's advanced communication systems enabling both space and polarization diversity. The proposed components are designed to meet the future ever-increasing consumer experience and technical requirements such as low loss, compact size, and low-cost fabrication. This directed the presented research to have a contribution into three major parts. The first part highlights the feeding structures, where mmWave PRGW directional couplers and differential feeding power divider are designed and validated. These components are among the most important passive elements of microwave circuits used in antennabeam-switchingnetworks. Different3-dBquadraturehybridcouplersandcrossover prototypes are proposed, featured with a compact size and a wide bandwidth beyond 10 % at 30 GHz. In the second part, a beam switching network implemented using hybrid couplers is presented. The proposed beam switching network is a 4 × 4 PRGW Butler matrix that used to feed a Magneto-electric (ME) dipole antenna array. As a result, a 2-D scanning antenna array with a compact size, wide bandwidth, and high radiation efficiency larger than84%isachieved. Furthergainenhancementof5dBiisachievedthroughdeployinga hybridgainenhancementtechniqueincludingAMCmushroomshapesaroundtheantenna array with a dielectric superstrate located in the broadside direction. The proposed scanning antenna array can be considered as a step toward the desired improvement in the data rate and coverage through enabling the space diversity for the communication link. The final activity is related to the development of high-gain wide-band mmWave antenna arrays for potential use in future mmWave applications. The first proposed configuration is a differential feeding circular polarized aperture antenna array implemented with PRGW technology. Differential feeding antenna designs offer more advantages than single- ended antennas for mmWave communications as they are easy to be integrated with differential mmWave monolithic ICs that have high common-mode rejection ratio providing an immunity of the environmental noise. The proposed differential feeding antenna array is designed and fabricated, which featured with a stable high gain and a high radiation efficiency over a wide bandwidth. Another proposed configuration is a dualpolarized ME-dipole PRGW antenna array for mmWave wireless communication. Dual polarizationisconsideredoneofthemostimportantantennasolutionsthatcansavecosts and space for modern communication systems. In addition, it is an effective strategy for multiple-input and multiple-output systems that can reduce the size of multiple antennas systems by utilizing extra orthogonal polarization. The proposed dual- polarized antenna array is designed to achieve a stable gain of 15 ± 1 dBi with low cross- polarization less than -30 dB over a wide frequency range of 20 % at 30 GHz

An Ultra-Wideband Circularly Polarized Asymmetric-S Antenna With Enhanced Bandwidth and Beamwidth Performance

This paper introduces an ultra-wideband circularly polarized (CP) asymmetric-S antenna with wide axial ratio beamwidth (ARBW) for C-band applications. The proposed antenna is realized by bending a linearly polarized dipole into asymmetric-S shape with variable trace width, which achieves CP radiation. Unlike the reported symmetric-S antenna, the proposed antenna is constituted with two unequal curved arms to enhance the bandwidth and beamwidth performances. Compared with the symmetric-S antenna, the proposed antenna demonstrates much wider AR bandwidth and wider ARBW over broader frequency range. A prototype is fabricated to verify the design principle. The measured and simulated results are very consistent and both indicate that the proposed antenna has a wide impedance bandwidth (VSWR <; 2) of 70.2% (3.58 to 7.46 GHz), and a wide 3-dB AR bandwidth of 84.8% (2.75 to 6.8 GHz). Moreover, maximum ARBW of 153° is achieved, and a 3-dB ARBW of more than 100° is maintained within a wide operation bandwidth of 46.3% (3.65-5.85 GHz)

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Multipolarization-reconfigurable air-filled substrate integrated waveguide cavity-backed slot antenna

A novel single-feed ultrawideband cavity-backed slot antenna with a reconfigurable polarization capability is demonstrated in substrate-independent air-filled substrate integrated waveguide (AFSIW) technology for Internet-of-Things applications in the [5.15-5.85] GHz frequency band of the unlicensed national information infrastructure. The antenna achieves an ultrawide impedance bandwidth by exploiting a double ring of slots and supports four switchable linear polarization states (+/- 45 degrees, 0 degrees, +45 degrees, and 90 degrees) by leveraging four quartets of p-i-n diodes. By electrically shorting the slots at well-defined positions by these p-i-n diodes, dynamic polarization reconfiguration is achieved by switching their dc bias current, supplied at the antenna feed through an external bias tee and routed from the antenna's back to front cavity plane via the AFSIW sidewalls. This new simple, yet effective, bias network enables the integration of all polarization control electronics inside the antenna cavity to protect them from environmental effects. Finally, measurements prove that the prototype exhibits an overlapping impedance bandwidth of 29%, from 4.85 to 6.45 GHz, and a stable conically shaped radiation pattern across the operating bandwidth with a 3 dB beamwidth of 45 degrees and a peak gain of 6.5 dBi for all four states

Design of a Novel Efficient High-Gain Ultra-Wide-Band Slotted H-Shaped Printed 2×1 Array Antenna for Millimeter-Wave Applications with Improvement of Bandwidth and Gain via the Feed Line and Elliptical Edges

This paper describes design procedure of a high-performance miniaturized antenna with an array configuration, which contributes to enhancing the communication system’s performance. The basic antenna features a compact size (6 x 6) mm2, and its single element is an H-shaped slotted patch printed on the top side of a Rogers RT5880 substrate, with a relative permittivity and thickness of 2.2 and 0.3 mm, respectively. The edge-to-edge distance of the 2 × 1 array antenna is 9 x 14 mm2, and the isolation between its radiation elements is 4.5 mm. To increase the capabilities of the antenna in terms of gain and bandwidth, we proceeded to use the 2 × 1 array configuration and then optimized the model via either the width of the feed line or the elliptical edges of the patch. The miniaturized array antenna achieved a peak gain of 12.56 dB, a directivity of 13.11 dBi, and a return loss of -47.52 dB at a resonance frequency of 91.5 GHz, with a radiation efficiency of more than 91% over an operating bandwidth of 15.83 GHz, ranging from 79.7 GHz to 95.6 GHz. The design and simulation results of the proposed antenna were obtained using the CST Studio software

Antennas And Wave Propagation In Wireless Body Area Networks: Design And Evaluation Techniques

Recently, fabrication of miniature electronic devices that can be used for wireless connectivity becomes of great interest in many applications. This has resulted in many small and compact wireless devices that are either implantable or wearable. As these devices are small, the space for the antenna is limited. An antenna is the part of the wireless device that receives and transmits a wireless signal. Implantable and wearable antennas are very susceptible to harmful performance degradation caused by the human body and very difficult to integrate, if not designed properly. A designer need to minimize unwanted radiation absorption by the human body to avoid potential health issues. Moreover, a wearable antenna will be inevitably exposed to user movements and has to deal with influences such as crumpling and bending. These deformations can cause degraded performance or a shifted frequency response, which might render the antenna less effective. The existing wearable and implantable antennas’ topologies and designs under discussion still suffer from many challenges such as unstable antenna behavior, low bandwidth, considerable power generation, less biocompatibility, and comparatively bigger size. The work presented in this thesis focused on two main aspects. Part one of the work presents the design, realization, and performance evaluation of two wearable antennas based on flexible and textile materials. In order to achieve high body-antenna isolation, hence, minimal coupling between human body and antenna and to achieve performance enhancement artificial magnetic conductor is integrated with the antenna. The proposed wearable antennas feature a small footprint and low profile characteristics and achieved a wider -10 dB input impedance bandwidth compared to wearable antennas reported in literature. In addition, using new materials in wearable antenna design such as flexible magneto-dielectric and dielectric/magnetic layered substrates is investigated. Effectiveness of using such materials revealed to achieve further improvements in antenna radiation characteristics and bandwidth and to stabilize antenna performance under bending and on body conditions compared to artificial magnetic conductor based antenna. The design of a wideband biocompatible implantable antenna is presented. The antenna features small size (i.e., the antenna size in planar form is 2.52 mm3), wide -10 dB input impedance bandwidth of 7.31 GHz, and low coupling to human tissues. In part two, an overview of investigations done for two wireless body area network applications is presented. The applications are: (a) respiratory rate measurement using ultra-wide band radar system and (b) an accurate phase-based localization method of radio frequency identification tag. The ultimate goal is to study how the antenna design can affect the overall system performance and define its limitations and capabilities. In the first studied application, results indicate that the proposed sensing system is less affected and shows less error when an antenna with directive radiation pattern, low cross-polarization, and stable phase center is used. In the second studied application, results indicate that effects of mutual coupling between the array elements on the phase values are negligible. Thus, the phase of the reflected waves from the tag is mainly determined by the distance between the tag and each antenna element, and is not affected by the induced currents on the other elements

Mm-wave high gain cavity-backed aperture-coupled patch antenna array

© 2013 IEEE. A wideband and high gain cavity-backed 4 × 4 patch antenna array is proposed in this paper. Each patch antenna element of the array is enclosed by a rectangular cavity and differentially-fed by the slot underneath. By optimizing the geometry of the radiating patch and the cavity, a very uniform E-field distribution at the antenna aperture is achieved, leading to the high array aperture efficiency and thus the gain. Taking advantages of the higher-order substrate integrated cavity excitation, the elements of the array are efficiently fed with the same amplitude and phase in a simplified feeding mechanism instead of the conventional bulky and lossy power-splitter-based feeding network. Measured results show the antenna bandwidth is from 56 to 63.1-GHz (16.1%) with the peak gain reaching 21.4 dBi. The radiation patterns of the array are very stable over the entire frequency band and the cross-polarizations are as low as -30 dB. These good characteristics demonstrate that the proposed array can be a good candidate for the future 60-GHz communication system applications