Stacked patch antenna and hybrid beamforming network for 5G picocell applications

This paper addresses the design of an antenna array for a portable picocell station with omnidirectional coverage. The proposed solution includes a stacked patch antenna as a single radiating element of the antenna array and a hybrid beamforming network. The antenna element works at 26 GHz with a bandwidth of 20% and a gain of approximately 8.5 dB along the operational bandwidth. The antenna is fed by a suspended stripline transitioned from a waveguide. This antenna element is used to compute a 5x12-element antenna array fed by the hybrid beamforming network. Results are analytically obtained for a fixed analog beamforming network that generates a csc squared pattern shape in elevation. Additionally, a digital beamforming network is computed to perform beamsteering for a desired set of constraints in the azimuth plane. Simulated results of the complete system yield promising insights on the capacity of the proposed design to provide omnidirectional coverage.

Design of novel radiating elements for SATCOM phased arrays in Ku-Band

Baptiste Fernand Hornecker

The present thesis deals with the design of a planar antenna array for the communication between a civil aircraft (Dassault's Falcon) and an Inmarsat satellite. The final goal is to provide high speed Internet access in X/Ku-Band (8-12GHz / 12-18GHz), and possibly even in K/Ka- Band (18-27GHz / 17-40GHz). The study starts with the Ku-Band only, then evolves towards the transmission band and finishes with their Ka-Band counterparts. The main constraint of the thesis is that the final result should be a low profile antenna that will be easy to integrate below the fuselage of an aircraft. At the same time, the antenna has to provide a beam steering mechanism in order to track the position of the targetted satellite while the aircraft is moving. The usual way to achieve it is to implement some dedicated electronic chips below each radiating element of array. Dassault Aviation has its own alternate and more mechanical oriented solutions. Since the communication system is intended for top-notch business jets produced in small series, cost is not here a decisive criterion. This thesis assumes the existence of the beam-steering system and concentrates on a proof of concept and careful design of the antenna elements that will constitute the final array. They have to satisfy tight constraints in terms of size, return loss, mutual coupling with neighbors, efficiency, radiation pattern and dual circular polarization quality. Printed multilayer antennas have been retained as the best candidates, and themain parts of the thesis have been dedicated to their study. The thesis concludes with the presentation of an apparently completely unrelated and independant topic, namely the simulation of nanoscale 2D planar structures based on Graphene. The rationale for this last chapter is to provide a prospective study of the use of Graphene to create a variable capacitance. This component is always needed in the beamforming network of reconfigurable and scanning arrays. Our laboratory is developing a deep knowledge of the electromagnetic properties of Graphene-based devices and these varicaps could lead to very interesting applications in high frequencies, once the Graphene technology has definitely progressed. Thanks to electrostatics Green's functions, a variable capacitor based on Graphene has been simulated, and a Quantumeffect -the Quantum capacitance of Graphene- has been successfully tackled from a numerical point of view.

EPFL2016

A simple & [and] accessible front-end satellite receiver for communications and e-learning in emerging countries

Olivier Videme Bossou

For the universities of the emergent countries, and those of Cameroon in particular, the fight to reach a durable development requires to know the needed scientific and technical information for their development, how to get it and to spread it out among partners in the country. Obviously, the complete answer to these preoccupations lies well beyond the framework of this project, but a projection, partial but highly significant, can nevertheless be obtained if one concentrates one's efforts on a specific technological field : in the present study, we shall treat of antennas for telecommunications systems. This subject is highly suitable as example and potential incubator for future achievements. The ultimate goal is to design and carry out the fabrication of a system of satellite communications adapted to the financial resources and to the development needs of the universities of the South. First of all, we will review the state of the art in satellite communication systems, both for already operating ones and also for new systems, still under development. Then we will determine which system of satellite telecommunications has a receiver and communication fees with affordable costs : our choice will be made on Worldspace satellite system, which was actually designed for developing countries. We will also review the status of planar antenna and low noise amplifier technology, and then explicit the basic challenge involved in our thesis project. One of the aims of this project is to use local wood as dielectric in SSFIP type antennas. Before using a material as dielectric in an antenna design, it must be characterized. Before carrying the characterization of local wood species, we will begin by reviewing some commonly used dielectric measurement techniques. Then we will carry out a series of measurements to characterize the species of wood growing in the Cameroonian forest. At the end of the series of measurements and according to the dielectric losses observed, we will select the species of wood best suited to make a good substrate for a microstrip antenna. Next, we will design, manufacture and test low cost antennas. These antennas must satisfy not only technical criteria compatible with those of the telecommunications system chosen but, even most importantly, it must meet socioeconomic criteria : the antennas must be manufactured with low cost and locally available materials, making use of simple technological processes. Once we have found the wood species that exhibits the lowest dielectric losses, we will simulate, and then manufacture the SSFIP type antenna with wood as substrate and aluminium as conducting element. Then we will measure its characteristics and check whether they are compatible with those of a Worldspace receiver. The signal received from the satellite by the antenna is very weak. It will be important to strengthen the received signal with a low noise amplifier (LNA) before connecting the antenna to the receiver. Thus the antenna and the LNA constitute an active antenna and form what we call here the radiofrequency (RF) front-end. We will design, manufacture and measure the LNA characteristics. A simple manufacturing process must be used to realize these antennas, because later on they must be manufactured locally in Cameroon : this is a determining challenge to ensure the economic independence, which is essential in our thesis project. Afterwards we will join the LNA to the planar antenna and connect the active antenna obtained in this manner to a commercial Worldspace receiver. Finally, we will perform receiving tests of the Worldspace radio station with the system designed. In parallel, our project includes a second goal, which presents an equivalent significance. We will use existing Matlab codes to develop an online course to teach antenna theory. In addition, at the end of the project and when the Cameroonian local manufacture would have started, we will put all algorithms used for the antenna design on the web site in a multi-media applet, together with a complete documentation of all the manufacturing technologies used. The courses that already exist in Lausanne and Yaounde, relating to the description of other types of antennas will be added, thus leading to a complete teachware that would ensure the durability and the dissemination of the results obtained, and would provide an invaluable tool for teaching and training.

EPFL2007

A portable picocell antenna for 5G

Danelys Rodríguez Avila

Deployable emergency communication systems are a backbone solution for replacing damaged network infrastructures and/or providing high-end services in case of an emergency event. It is important that such systems are up-to-date with the latest mobile network technology, for enabling connectivity to users and profiting from its enhanced capabilities. The advent of 5G promises higher data rates, lower latencies and improved quality of services when compared to previous generations. To achieve that, mm-Waves have been identified as a key element due to the wide available spectrum. The implementation of deployable emergency communication systems compatible with 5G mm-Waves technologies, thus benefiting from its prospective advantages, is of great interest. This thesis focuses on 5G mm-Waves antenna design for this kind of applications. The high network capacity demand, the unfavourable channel conditions at mm-Waves and the still underdeveloped related radio frequency (RF) technology define a group of challenging requirements on the antenna design. While directive antennas are required to mitigate the attenuation with distance at these bands, omnidirectional coverage still needs to be provided. In addition, wide bandwidth operation, high efficiency, and low cost and power consumption are desired. In this context, antennas with multibeam forming capabilities have been widely acknowledged as a key enabling technology to support 5G wireless communications, representing an attractive solution to provide omnidirectional coverage while supporting Multiple Input Multiple Output (MIMO) techniques. In this thesis, the design and implementation of a broadband efficient multibeam antenna for a portable picocell station are investigated. The picocell scenario in the context of emergency communications is studied and the antenna link budget is calculated considering mm-Waves propagation properties and available information on the upcoming standard. This leads to the definition of the design requirements and a preliminary antenna architecture that consists of an MxN antenna fed by a hybrid beamforming network (HBFN). This architecture is a promising approach for making multibeam antennas cost- and energy-efficient according to the latest research. The synthesis of the HBFN was realized considering the design constraints in elevation and azimuth such that the subarray, fed by an analog beamforming network, provides a csc2 pattern shape in elevation while M subarrays are controlled by a digital beamforming network to generate multiple orthogonal beams in azimuth. The antenna subarray was designed, fabricated and measured. Based on this, a study of the antenna array beamsteering capabilities in azimuth was carried out. After investigating the main parameters involved in improving its performance, the subarray design was optimized accordingly. The proposed antenna consists in a 12x6 array that works at 26 GHz with an impedance bandwidth higher than 12%. The radiation pattern shape in elevation is preserved over 7.3% of bandwidth. The antenna gain is superior to 10 dBi along the band of interest with a maximum value of 15 dBi. Simulated and measured results were compared, and the antenna beamsteering performance was tested for different sets of constraints indicating promising capabilities for a wide range of deployment scenarios. The proposed and validated design meets the requirements of the targeted applications on a practical low-profile implementation.

EPFL2021