Design of a Multimode MIMO Antenna Using the Theory of Characteristic Modes

In this communication, the design procedure of a multimode Multiple-Input Multiple-Output (MIMO) antenna is presented. The antenna consists of a metallic ring antenna operating with different orthogonal modes, whose performance in a MIMO system is similar to traditional antenna arrays. Thus, a compact MIMO antenna is obtained, which is very suitable for mobile terminals. A modal analysis of the antenna is carried out first by means of the Theory of Characteristic Modes, in order to identify the different radiating modes of the antenna. Then a set of feeding configurations is proposed so as to excite these modes. As the modes must operate in the same frequency band, a loading technique is used in the antenna in order to shift the resonance frequency of the modes to the proper band

Modelling Aspects of Planar Multi-Mode Antennas for Direction-of-Arrival Estimation

Multi-mode antennas are an alternative to classical antenna arrays, and hence a promising emerging sensor technology for a vast variety of applications in the areas of array signal processing and digital communications. An unsolved problem is to describe the radiation pattern of multi-mode antennas in closed analytic form based on calibration measurements or on electromagnetic field (EMF) simulation data. As a solution, we investigate two modeling methods: One is based on the array interpolation technique (AIT), the other one on wavefield modeling (WM). Both methods are able to accurately interpolate quantized EMF data of a given multi-mode antenna, in our case a planar four-port antenna developed for the 6-8.5 GHz range. Since the modeling methods inherently depend on parameter sets, we investigate the influence of the parameter choice on the accuracy of both models. Furthermore, we evaluate the impact of modeling errors for coherent maximum-likelihood direction-of-arrival (DoA) estimation given different model parameters. Numerical results are presented for a single polarization component. Simulations reveal that the estimation bias introduced by model errors is subject to the chosen model parameters. Finally, we provide optimized sets of AIT and WM parameters for the multi-mode antenna under investigation. With these parameter sets, EMF data samples can be reproduced in interpolated form with high angular resolution

Breaking FOV-Aperture Trade-Off with Multi-Mode Nano-Photonic Antennas

Nano-photonic antennas are one of the key components in integrated photonic transmitter and receiver systems. Conventionally, grating couplers, designed to couple into an optical fiber, suffering from limitations such as large footprint and small field-of-view (FOV) have been used as on-chip antennas. The challenge of the antenna design is more pronounced for the receiver systems, where both the collected power by the antenna and its FOV often need to be maximized. While some novel solutions have been demonstrated recently, identifying fundamental limits and trade-offs in nano-photonic antenna design is essential for devising compact antenna structures with improved performance. In this paper, the fundamental electromagnetic limits, as well as fabrication imposed constraints on improving antenna effective aperture and FOV are studied, and approximated performance upper limits are derived and quantified. By deviating from the conventional assumptions leading to these limits, high-performance multi-mode antenna structures with performance characteristics beyond the conventional perceived limits are demonstrated. Finally, the application of a pillar multi-mode antenna in a dense array is discussed, an antenna array with more than 95% collection efficiency and 170∘ FOV is demonstrated, and a coherent receiving system utilizing such an aperture is presented

Diseño de una antena multimodo sobre substrato textil para aplicaciones corporales

El objetivo principal del presente trabajo es el diseño de una antena sobre substrato textil que presente comportamiento multimodo operando a 2.45 GHz bajo el estándar Zigbee. La antena proporcionará comportamiento MIMO gracias a la excitación simultánea de varios modos de radiación con diagramas ortogonales, y será adecuada para aplicaciones corporales. El substrato textil empleado será un tejido 100% algodón de características electromagnéticas desconocidas inicialmente. De aquí deriva otro de los objetivos principales del presente proyecto, que es la caracterización del textil empleado como substrato de la antena. Con el fin de determinar las propiedades dieléctricas del material textil se estudiarán distintas técnicas de caracterización. El empleo de un substrato dieléctrico textil dotará a la antena de la flexibilidad necesaria para ser empleada en redes de sensores que trabajen en entornos de área corporal.A textile antenna designed for Zigbee Wireless Body Area Network (WBAN) is presented. The antenna is based on a capacitive loaded metallic circular ring that exhibits multimode characteristic at 2.4 GHz. The multimode behaviour is obtained using four feeding ports excited with specific phase configurations. The proposed antenna can be easily integrated into clothing due to its thickness and flexibility. Furthermore, its multimode behaviour helps to reduce the attenuation originated by NLOS (Non Line of Sight) environments and multipath propagation. The performance of the multimode antenna is similar to a MIMO system, but using a single antenna, so the space necessary in human body is minimized. For this reason, the multimode antenna is the best solution for WBAN applications.Santiso Bellón, J. (2011). Diseño de una antena multimodo sobre substrato textil para aplicaciones corporales. Universitat Politècnica de València. http://hdl.handle.net/10251/14568Archivo delegad

Relations between channel capacity and antenna Radiation pattern for multiple-input multipleoutput Systems

ได้รับทุนอุดหนุนการวิจัยจากมหาวิทยาลัยเทคโนโลยีสุรนารี ปีงบประมาณ พ.ศ.255

Design and Simulation of Adaptive and Multi-Rate Massive MIMO Systems for Terahertz Band Communication

[ANGLÈS] The communications in the Terahertz Band (0.06-10 THz) are a promising new paradigm for wireless communications in the next decade. Their large available bandwidth, combined with the development of graphene antennas, characterized by their reduced dimensions, will enable establishing systems in environments that were very limited until this moment due to technological limitations, such as nanocommunications, as well as will help to solve the overwhelming occupation of the electromagnetic spectrum, which limits tha capacity for wireless communications. The novelty of this technology implies the need for studying and improving diverse aspects of the sistems, such as the channel characteristics, the transmitters and receivers, the modulation and the associated protocols, among others. New models and solutions should be developed and investigated to be applied in the Terahertz context. Furthermore, in the last years the use of multiple antennas for transmission and reception, known as MIMO, has been extensively studied, for applications in increasing capacity, improving the signal-to-noise ration or saving energy by concentrating the power in particular directions. When the number of transmitting or receiving elements is increased to the order of hundreds, we name it Massive MIMO. In this work we have studied the applications of Massive MIMO in the Terahertz Band. First, we develop diverse configurations to concentrate the power in a narrow angle through the use of beamforming, and thus prevent the high path losses that these frequencies produce. Then, we analyze the use of a single antenna with several subarrays to offer multiple beams, with the aim of serving more than one user or providing diversity, along with the corresponding study of the interference impact over the capacity. Finally, we present configurations that enable working in different frequencies and we discuss the improvement achieved in capacity, as well as the reduction of possible interferences.[CASTELLÀ] Las comunicaciones en la banda de Terahertz (0.06-10 THz) promete ser el nuevo paradigma de comunicaciones inalámbricas en la próxima década. Su amplísimo ancho de banda, combinado con el desarrollo de antenas de grafeno de dimensiones muy reducidas, permitirá establecer sistemas en entornos hasta ahora muy limitados por la tecnología existente, tales como las nanocomunicaciones, y además ayudará a solventar el problema de sobreocupación del espectro, que acota la capacidad de los enlaces sin cables. La novedad de esta tecnología conllevará la necesidad de estudiar y mejorar diversos aspectos de los sistemas, tales como las características del canal, los transmisores y receptores, la modulación y los protocolos asociados, entre otros. Se deben investigar y desarrollar nuevos modelos y soluciones para ser aplicados en el contexto de los Terahertz. Por otro lado, en los últimos años se ha estudiado extensamente el uso de múltiples antenas en transmisión y recepción, conocido como MIMO, y sus aplicaciones para incrementar la capacidad de los sistemas, combatir el ruido y ahorrar energía mediante la concentración de potencia en determinadas direcciones. Cuando el número de elementos transmisores y receptores crece hasta el orden de las centenas, MIMO pasa a denominarse Massive MIMO. En este trabajo estudiaremos las aplicaciones del uso de Massive MIMO en la banda de los Terahertz. En primer lugar, se desarrollaran diversas configuraciones para concentrar la potencia mediante beamforming, y así combatir las altas pérdidas de propagación que se producen a estas frecuencias. A continuación, se analiza el uso de una antena para ofrecer diversos haces de potencia, con el objetivo de servir a más de un usuario, con el correspondiente estudio del impacto de interferencias sobre la capacidad. Por último, se presentan configuraciones que permiten trabajar a distintas frecuencias y se discute la mejora de capacidad disponible, además de la reducción de posibles interferencias.[CATALÀ] Les comunicacions a la banda dels Terahertz (0.06-10 THz) prometen ser el nou paradigma de comunicacions inalàmbriques a la propera dècada. El seu enorme ample de banda, combinat amb el desenvolupament d'antenes de grafè de dimensions molt reduïdes, permetrà establir sistemes en entorns fins ara molt limitats per la tecnologia existent, tals com les nanocomunicacions, i a més a més ajudarà a solventar el problema de sobreocupació de l'espectre, que fita la capacitat dels enllaços sense cables. La novetat d'aquesta tecnologia implicarà la necessitat d'estudiar i millorar diversos aspectes dels sistemes, tals com les característiques del canal, els transmissors i receptors, la modulació i els protocols associats, entre d'altres. Se deuen investigar i desenvolupar nous models i solucions per ser aplicats al context dels Terahertz. D'altra banda, als darrers anys s'ha estudiat extensament l'ús de múltiples antenes en transmissió i recepció, conegut com MIMO, i llurs aplicacions per incrementar la capacitat dels sistemes, combatre el soroll i estalviar energia mitjançant la concentració de potència en determinades direccions. Quan el nombre d'elements transmissors i receptors creix fins a l'ordre de les centenes, MIMO passa a denominar-se Massive MIMO. En aquest treball estudiarem les aplicacions de l'ús de Massive MIMO a la banda dels Terahertz. En primer lloc, se desenvolupen diverses configuracions per concentrar la potència mitjançant beamforming, i així combatre les altes pèrdues de propagació que es produeixen a aquestes freqüències. A continuació, s'analitza l'ús d'una antena amb diversos subarrays per oferir més d'un feix de potència, i poder servir a més d'un usuari o possibilitar la diversitat, acompanyat del corresponent estudi de l'impacte de les interferències sobre la capacitat. Finalment, es presenten configuracions que permeten treballar a diferents freqüències i es discuteix la millora de capacitat disponible, així com la reducció de possibles interferències

High Gain Antenna Array Design for 5G & MIMO Antenna Systems using Microstrip Ridge Gap Waveguide

The demand for high data rates and the unavailability of low-frequency bands have driven the need to explore and develop millimeter-wave (mm-wave) frequency bands. Indeed, the development of mm-wave frequencies has led to smaller radio frequency (RF) components and more compact profiles, creating more design constraints and challenges. Millimeter-wave technologies are the best-suited candidates that meet the requirements of 5G standards; specifically, for indoor communication, which requires higher gain and more directive beams. Gap waveguide technologies can be used to design high-gain antenna arrays and multiple input multiple output antenna systems (MIMO). In this thesis, we are mainly focusing on Microstrip Ridge Gap Waveguide (MRGW) to design the antenna array systems for the 60 GHz band. Therefore, it is necessary to facilitate the design procedures and propose new design techniques. Here, we propose new design techniques for a large antenna array system using MRGW. The work of this thesis can be divided into two parts. Firstly, developing an efficient modeling and design tool for the MRGW to facilitate the design process. Recently, the use of MRGW has increased due to the need for self-packaged and low loss structures for millimeter-wave applications. The MRGW consists of a grounded textured surface, which is representing an artificial magnetic conductor (AMC) surface. The AMC surface is loaded with a thin low dielectric constant substrate with a printed strip topped with another air-filled or dielectric-filled substrate in which the wave propagates between the strip and the conducting plate covering such a substrate. Currently, full-wave and optimization tools are usually used to design the MRGW structure, which makes the design slow and computationally expensive. Thus, an efficient modeling and design tool for the MRGW is proposed. Empirical expressions are developed for different MRGW parameters to provide the effective dielectric constant, characteristic impedance, and the dispersion effect. The expressions are verified with the full-wave solution. The results show the potential of the proposed approach in modeling and designing the MRGW structure. Secondly, an efficient procedure to design a large finite planar array and its corporate feeding network is presented. The procedure is verified by an 8 × 8 and 16 ×16 array of magneto-electric (ME) dipoles fed by a network of MRGW. The procedure is based on designing the corporate feeding network by replacing the elements ports with the corresponding effective input impedance of each element that accounts for the mutual coupling between the antenna elements. In addition, the far-field characteristics of the array parameters such as the directivity, gain, and radiation patterns are predicted using pattern multiplication, including the mutual coupling effects. The results are verified with the full-wave numerical solution. The procedure requires limited resources and speed up the design cycle. The use of the MRGW helps in having the feeding network lines to be titer than using the ridge gap technology. Thus, allowing the distance between the radiating elements becomes smaller than one wavelength to avoid grating lobes. In addition, to avoid undesired bends and very tight lines that cause undesired interaction between the lines, unique power dividers are designed. Furthermore, a transition from waveguide WR-15 to the MRGW is proposed to feed two halves of the array antenna perfect out of phase at all frequencies and rotating each half to form a mirrored array that better radiation pattern symmetry and low cross-polarization. Then, this procedure is implemented to design a circularly polarized antenna array with excellent performance. To further enhance the antenna, gain, and reduce the number of elements, a superstrate dielectric lens with the proper parameters is added. Study of a 4 × 4 MIMO system is studied, where each antenna is a sub-array to achieve the high gain requirements. Finally, A low-profile, compact, and high-efficiency monopulse array antenna has been presented. The monopulse is built based on a hybrid coupler that has a wideband response for the reflection and the transmission coefficients. Then the monopulse system is used to present a multiplexing antenna system for short-range in the near filed region wireless communication. The multiplexing system works as a MIMO system that has four independent channels. The performance of the system is evaluated through the simulation, which shows that it can be a promising candidate for the next wireless communication systems