Small Footprint Multilayered Millimeter-Wave Antennas and Feeding Networks for Multi-Dimensional Scanning and High-Density Integrated Systems

This paper overviews the state-of-the-art of substrate integrated waveguide (SIW) techniques in the design and realization of innovative low-cost, low-profile and low-loss (L3) millimeter-wave antenna elements, feeding networks and arrays for various wireless applications. Novel classes of multilayered antenna structures and systems are proposed and studied to exploit the vertical dimension of planar structures to overcome certain limita-tions in standard two-dimensional (2-D) topologies. The developed structures are based on two techniques, namely multi-layer stacked structures and E-plane corners. Differ-ent E-plane structures realised with SIW waveguide are presented, thereby demonstrating the potential of the proposed techniques as in multi-polarization antenna feeding. An array of 128 elements shows low SLL and height gain with just 200g of the total weight. Two versions of 2-D scanning multi-beam are presented, which effectively combine frequency scanning with beam forming networks. Adding the benefits of wide band performance to the multilayer structure, two bi-layer structures are investigated. Different stacked antennas and arrays are demonstrated to optimise the targeted antenna performances in the smallest footprint possible. These structures meet the requirement for developing inexpensive compact millimeter-wave antennas and antenna systems. Different structures and architectures are theoretically and experimentally studied and discussed for specific space- and ground-based appli-cations. Practical issues such as high-density integration and high-volume manufacturability are also addressed

Design and Implementation of High Gain 60 GHz Antennas for Imaging/Detection Systems

Recently, millimeter wave (MMW) imaging detection systems are drawing attention for their relative safety and detection of concealed objects. Such systems use safe non-ionizing radiation and have great potential to be used in several applications such as security scanning and medical screening. Antenna probes, which enhance system performance and increase image resolution contrast, are primarily used in MMW imaging sensors. The unlicensed 60 GHz band is a promising band, due to its wide bandwidth, about 7 GHz (57 - 64 GHz), and lack of cost. However, at 60 GHz the propagation loss is relatively high, creating design challenges for operating this band in MMW screening. A high gain, low profile, affordable, and efficient probe is essential for such applications at 60 GHz. This thesis’s focus is on design and implementation of high gain MMW probes to optimize the performance of detection/imaging systems. First, single-element broadside radiation microstrip antennas and novel probes of endfire tapered slot high efficient antennas are presented. Second, a 57-64 GHz, 1 × 16-element beam steering antenna array with a low-cost piezoelectric transducer controlled phase shifter is presented. Then, a mechanical scanner is designed specifically to test proposed antenna probes utilizing low-power 60 GHz active monostatic transceivers. The results for utilizing proposed 60 GHz probes show success in detecting and identifying concealed weapons and explosives in liquids or plastics. As part of the first research theme, a 60 GHz circular patch-fed high gain dielectric lens antenna is presented, where the prototype’s measured impedance bandwidth reaches 3 GHz and a gain of 20 dB. A low cost, 60 GHz printed Yagi antenna array was designed, optimized, fabricated and tested. New models of the antipodal Fermi tapered slot antenna (AFTSA) with a novel sine corrugated (SC) shape are designed, and their measured results are validated with simulated ones. The AFTSA-SC produces a broadband and high efficiency pattern with the capacity for high directivity for all ISM-band. Another new contribution is a novel dual-polarized design for AFTSA-CS, using a single feed with a pair of linearly polarized antennas aligned orthogonally in a cross-shape. Furthermore, a novel 60 GHz single feed circularly polarized (CP) AFTSA-SC is modeled to radiate in the right-hand circularly polarized antenna (RHCP). A RHCP axial ratio bandwidth of < 3dB is maintained from 59 to 63 GHz. In addition, a high gain, low cost 60 GHz Multi Sin-Corrugations AFTSA loaded with a grooved spherical lens and in the form of three elements to operate as the beam steering antenna is presented. These probes show a return loss reduction and sidelobes and backlobe suppression and are optimized for a 20 dB or higher gain and radiation efficiency of ~90% at 60 GHz. The second research theme is implementing a 1 × 16-element beam steering antenna array with a low-cost piezoelectric transducer (PET) controlled phase shifter. A power divider with a triangular feed which reduces discontinuity from feed lines corners is introduced. A 1 × 16-element array is fabricated using 60 GHz AFTSA-SC antenna elements and showed symmetric E-plane and H-plane radiation patterns. The feed network design is surrounded by electromagnetic band-gap (EBG) structures to reduce surface waves and coupling between feed lines. The design of a circularly polarized 1 × 16-element beam steering phased array with and without EBG structures also investigated. A target detection investigation was carried out utilizing the proposed 60GHz antennas and their detection results are compared to those of V-band standard gain horn (SGH). System setup and signal pre-processing principle are introduced. The multi-corrugated MCAFTSA-SC probe is evaluated with the imaging/detection system for weapons and liquids concealed by clothing, plywood, and plastics. Results show that these items are detectable in clear 2D image resolution. It is believed that the 60 GHz imaging/detection system results using the developed probes show potential of detecting threatening objects through screening of materials and public

High Gain Broadband mm-Wave Antenna Arrays for Short-range Wireless Communication Systems

Recently, the ever-increasing demand for fifth-generation (5G) wireless applications has turned millimeter-wave (mm-wave) multi-beam array antenna into quite a promising research direction. Besides offering a remarkable bandwidth for high-speed wireless connectivity, the short wavelengths (1 to 10 mm) of mm-wave signals makes the size of the antenna array with beamforming network (BFN) compatible with a transceiver front-end. The high losses associated with mm-wave wireless links and systems considered the foremost challenge and may restrict the wireless communication range. Therefore, a wideband substrate integrated waveguide (SIW)-based antenna with high gain and beam scanning capabilities would be a solution for these challenges, as it can increase the coverage area of mm-wave wireless systems and mitigate the multipath interference to achieve a high signal to noise (S/N) ratio, and thereby fulfill the link budget requirements. This thesis focuses on the analysis and design of single- and multi-beam mm-wave antenna arrays based on SIW technology to fulfill the growing demand for wideband high-gain planar antenna arrays with beam steering capability at V-band. A tapered slot antenna (TSA) and cavity-backed patch antenna are used as the main radiators in these systems to achieve high-gain and high efficiency over a wide range of operating frequencies. Accordingly, numerous design challenges and BFN-related issues have been addressed in this work. Firstly, an antipodal Fermi tapered slot antenna (AFTSA) with sine-shaped corrugations is proposed at V-band. The antenna provides a flat measured gain of 20 dB with a return loss better than 22 dB. In addition, A broadband double-layer SIW-to-slotline transition is proposed to feed a planar linearly tapered slot antenna (PLTSA) covering the band 46-72 GHz. This new feeding technique, which addresses the bandwidth limits of regular microstrip-to-slotline transitions and avoids the bond wires and air bridges, is utilized to feed a 1x4 SIW-based PLTSA array. Secondly, a new cavity-backed aperture-coupled patch antenna with overlapped 1-dB gain and impedance bandwidth of 43.4 % (56-87 GHz) for |S11| < -10 dB and an average gain of 8.2 dBi is designed. A detailed operating principle is presented. Based on the proposed element, an SIW based 1x8 array is constructed, whose beam-shape is synthesized by amplitude tapering according to Taylor distribution to reduce the sidelobe level. Moreover, a four-layered 4x4 cavity-backed antenna array with a low-loss full-corporate SIW feed network is implemented for gain and aperture efficiency enhancement. The measured results exhibited a bandwidth of 38.4 % (55.2-81.4 GHz) for |S11| < -10 dB and a gain of 20.5 dBi. A single-layer right-angle transition between SIW and air-filled WR15 waveguide along with an equivalent circuit model is introduced and used to measure the performance of both proposed linear and planar arrays. Thirdly, two 1-D scanning multi-beam array designs based on SIW technology, at 60 GHz, have been presented. The first design is a compact multi-beam scanning 4x4 slot antenna array with broadside radiation. The BFN is implemented using a dual-layer 4x4 Butler matrix, where the 450 and 00 phase shifters are designed on a separate layer with different permittivity, resulting in a significant size reduction compared to a conventional single layer. A detailed theoretical analysis, principle of operation and the circuit-model of the proposed phase shifter have been discussed, showing less desperation characteristics compared to ordinary phase shifters. The measured results show an azimuthal coverage of 1210. The second design is a wideband high gain multi-beam tapered slot antenna array with end-fire radiation. An SIW Butler matrix with a modified hybrid crossover is used as a BFN. The fabricated prototype exhibits a field of view of 970 in the azimuthal plane, with measured gain ranges from 12.7 to 15.6 dBi. Lastly, a novel three-layered SIW-fed cavity-backed linearly polarized (LP) patch antenna element is presented, covering a bandwidth of 36.2 % (53-76.4 GHz) with a flat gain ranging from 7.6 to 8.2 dBi. A compact two-layered beam forming network is designed with a size reduction of 28 % compared to a standard one-layered BFN without affecting its s-parameters. The results show that the impedance bandwidth is 31.1 % (51.5-70.5 GHz) for |S11|<-16 dB with an average insertion loss of 1.3 dB. The proposed antenna element and BFN are employed to form a compact 2x2 multibeam array at 60 GHz for 2-D scanning applications. The array shows a bandwidth better than 27 % with a radiation gain of up to 12.4 dBi and radiation efficiency of 80%. The multi-beam array features four tilted beams at 330 from a boresight direction with 450, 1350, 2250 and 3150 in azimuth directions, i.e., on e beam in each quadrant

High Gain Planar Antenna Structures for Ka-band Applications

Antennas are an essential part of a communication system as they control a coverage area of the signal. The millimeter wave band has the potential to offer numerous radio applications which require the large bandwidth channels. Due to the current cellular subscribers’ demand of higher data rates, even cellular communication is expected to move in millimeter wave communications at Ka band of 26.5 GHz to 40 GHz. However, millimeter waves are sensitive to the high degree of atmospheric and oxygen absorption losses. This challenge of the millimeter wave communication can be tackled by employing high gain antennas. In addition, modern electronic products require compact handheld devices to offer the user-friendly system as well as capture the market. Therefore, planar antenna structures are apt for these communication systems. In this thesis, two antenna structures are presented at the Ka band for millimeter wave communications. Initially, four element patch antenna is presented for high gain in the broadside direction. Patch elements are excited using an aperture coupling from 50Ω microstrip line. Air-gap cavity is used to improve the impedance bandwidth of the design. This structure obtains a relatively moderate impedance bandwidth of 4.6%. The proposed four-element patch antenna exhibits a flat gain over an operating band with 13.8 dB gain at the design frequency. The antenna achieves a wide beamwidth of 700 in H plane. In addition, side lobe levels in E and H planes are -14.5 dB and 23 dB respectively. For the second prototype, an Antipodal Fermi-Linear Tapered Slot Antenna (AFLTSA) is presented to achieve the wide impedance bandwidth with high flat gain for endfire radiation. Substrate Integrated waveguide (SIW) technique is utilized to feed the AFLTSA which reduces insertion losses of the structure. Fermi-Dirac distributed curve in conjunction with a linear curve for a tapered slot increases the coupling of the electric field from a substrate integrated waveguide to the tapered slot. Knife edge rectangular corrugation profile is used at edges of AFLTSA in order to reduce the side lobes and cross polarization levels of radiation pattern. The proposed structure achieves the wide impedance bandwidth to support requirements for high data rate channels. Measurement results from a fabricated prototype exhibit a flat gain over an entire operating frequency band with 16.4 dB gain at 28 GHz. The wide impedance bandwidth is achieved with return loss below 15 dB. Proposed structure has low side lobe levels of -13.9 dB in H plane and -19.5 dB in E plane. In addition, it offers a low cross polarization level of -22 dB

Conception et réalisation d'un réseau d'antenne 8x16 éléments et de composants tridimensionnels à ondes millimétriques à base d'interconnexions verticales sur guides intégrés au substrat

RÉSUMÉ Les systèmes d'imagerie passives à ondes millimétriques nécessitent des antennes de taille compacte et à faible coût, présentant un gain élevé, de faibles pertes et une grande efficacité. Afin de réaliser une antenne satisfaisant ces exigences, une structure d'alimentation tridimensionnelle compacte, associée à 8x16 antennes éléments à rayonnement longitudinal à fort gain, est présentée dans ce mémoire. L’ensemble de contributions réalisées dans le cadre de ce travail sera décrit comme suit. Premièrement, pour être capable de construire ce réseau diviseur/combineur de puissance non planaire exclusivement avec la technologie du guide d’ondes intégré au substrat (GIS) sans l'utilisation de transitions en microruban, en fentes ou en guide d'ondes métallique pour passer du plan-H au plan-E, un coin plan-E uniquement basé sur la technologie (GIS) est étudié, analysé et démontré pour la première fois. Cette interconnexion GIS verticale, qui peut être fabriquée avec des circuits imprimés ou d'autres procédés similaires, amène des avantages attractifs en termes de coûts, de flexibilité et d’intégrabilité. Deux circuits prototypes avec des bras verticaux tournés respectivement de 0 et 45 degrés sont fabriqués. La version standard montre des pertes d'insertion de 0,5 dB dans la bande de 30 à 40 GHz, tandis que celle pivotée présente 0,7 dB de pertes sur la même plage de fréquences. Avec ce coude, une jonction–T plan-E est étudiée et conçue. Les résultats mesurés montrent 10 dB de pertes par réflexion sur 19% de largeur bande autour de 35 GHz avec moins de ± 4 degrés de déséquilibre de phase. Un diviseur T-magique large bande optimisé est démontré et fabriqué. Les résultats simulés et mesurés montrent une puissance répartie uniformément et un très bon isolement avec de faibles pertes par réflexion. En associant deux antennes avec deux coudes aux bras verticaux pivotés de 45 degrés et dupliqués en miroir, un système de double polarisation est obtenu, montrant une isolation de plus 20 dB de 32 à 40 GHz. Deuxièmement, une antenne à fente corrugée Fermi à rayonnement longitudinal alimentée en GIS avec un faisceau étroit et une large bande est fabriquée. Le gain réalisé en mesures est d'environ 18,4 dBi. Une fente évasée en air créée au centre de l’antenne, lorsque cette dernière est utilisée dans un réseau, vise à réduire le couplage entre deux éléments adjacents.---------- ABSTRACT Passive millimeter-wave imaging systems require compact-size, low-cost, high gain, low-loss and high-efficiency antennas. In order to realize an antenna satisfying those requirements, a compact three dimensional feeding structure in connection with 8x16 high-gain, high-efficiency endfire radiating elements are presented in this thesis. A number of contributions are made in this work, which will be described as follows. First, to be able to construct this non-planar power dividing/combining network exclusively with substrate integrated waveguide (SIW) technology without the use of any microstrip, slot-line or metallic waveguide for H-to-E-plane transition, a right angle E-plane corner solely based on (SIW) technology is studied, analyzed and demonstrated for the first time. This SIW vertical interconnect, which can be made with PCB or other similar processes, presents attractive advantages in terms of cost, flexibility and integration. Two circuit prototypes with both 0 and 45 degree vertical rotated arms are fabricated. The standard version has 0.5 dB of insertion loss from 30 to 40 GHz while the rotated one gives 0.7 dB over the same frequency range. With this bend, an E-plane T-junction is studied and designed. Measured results show 10 dB return loss over 19 % of bandwidth at 35 GHz with less than ±4 degree phase imbalance. An optimized wideband magic-T splitter is fabricated and demonstrated. Both simulated and measured results show evenly distributed power with very good isolation and return loss. By associating two antennas with two mirror duplicated 45 degree vertical rotated arm bends, a dual polarization system is obtained, showing a 20 dB isolation over 32-40 GHz. Second, an optimized wideband end-fire corrugated SIW fed Fermi tapered slot antenna with narrow beamwidth is fabricated. The realized gain in our measurement is about 18.4 dBi. To enhance its performance when used in an array, a taper shaped air gap is created in the center of the antenna to reduce the coupling between two adjacent elements. Third, an SIW 16 way power divider is designed with Villeneuve modified distribution in order to obtain low side lobe level (SLL). A 16 element array using the Fermi antenna is fabricated

Photonic heterodyne pixel for imaging arrays at microwave and MM-Wave frequencies

The use of photonic heterodyne receivers based on semiconductor optical amplifiers to be used in imaging arrays at several GHz frequencies is evaluated. With this objective, a 3×3 imaging array based on such photonic pixels has been fabricated and characterized. Each of the receiving optoelectronic pixels is composed of an antipodal linear tapered slot antenna (LTSA) that sends the received RF signal directly to the electrical port of a semiconductor opticalamplifier (SOA) acting as the optoelectronic mixer. Both the local oscillator (LO) and the intermediate frequency (IF) signals are directly distributed to/from the array pixels using fiber optics, that allows for remote LO generation and IF processing to recover the image. The results shown in this work demonstrate that the performances of the optoelectronic imaging array are similar to a reference all-electronic array, revealing the possibility of using this photonic architecture in future high-density, scalable, compact imaging arrays in microwave and millimeter wave ranges.Publicad

Analysis and Design of Substrate Integrated Waveguide-based Antennas for Millimeter Wave Applications

Recently, there has been increasing interest and rapid growth in millimeter wave (MMW) antennas and devices for use in diverse applications, services and technologies such as short-range communication, future mm-wave mobile communication for the fifth generation (5G) cellular networks, and sensor and imaging systems. Due to the corresponding smaller wavelength, mm-wave frequencies offer the advantage of physically smaller antennas and circuits as well as the availability of much wider bandwidth compared to microwave frequencies. It is important to design millimeter wave antennas with high gain characteristics due to their high sensitivity towards atmospheric absorption losses. Moreover, millimeter wave antennas can have wide bandwidth and are suitable for applications in large frequency range. In this thesis, planar antennas are designed using substrate integrated waveguide (SIW) technology to have low losses, high quality factor, and low fabrication cost. Firstly, an antipodal fermi linear tapered slot antenna (AFLSTA) with sine corrugations at the side edges at 32.5 GHz is presented, which has a wide impedance bandwidth greater than 30 %, in order to support the high data rate channels. This antenna has a high gain of 12.6 dB and low side lobe levels (better than - 17 dB) in both E and H planes. This antenna is studied and analyzed in array and beamforming configurations to meet requirements of millimeter wave applications. In order to obtain high gain and narrow beamwidth pattern, a 1 × 8 AFLTSA array using SIW power divider network is presented. The design characteristics of the power divider network are presented in this thesis, which help in calculating the performance characteristics of this array structure. This array has an acceptable bandwidth of 14.7 % (30-35 GHz) with high gain of 20.4 dB and 8.35° 3 dB beamwidth. The side lobe levels are also improved using this SIW power divider network and are lower than -25 dB in E-plane and -15 dB in H-plane respectively. This antenna has a radiation efficiency greater than 93% over the whole bandwidth. The second research theme is beamforming of AFLTSA antenna. This beamforming is performed using multi-beam antenna concept in which the beam is rotated with a help of compact beamforming network and excitation from different input ports. The design methodology for 2 × 2 and 4 × 4 subarray beamforming networks is presented along with their current distributions illustrating the beamforming process. These subarrays possess wide impedance bandwidth between 29-36 GHz. Moreover, these subarrays are able to achieve gain between 12-15 dB with narrow beamwidth reaching till 11°. All the results along with the numerical data is presented in this thesis. This antenna is suitable candidate for millimeter wave wireless communications and imaging systems

空洞誘電体を用いた屈折率分布型レンズに関する研究

Tohoku University陳強課