Teaching
• G.J. van Werkhoven (Universiteit Twente/ Thales Nederland B.V.)
Course description
Antennas and propagation of radio signals are a fundamental aspect of communications and radar as well as any other device that will radiate or receive electromagnetic waves over an air interface. Smart antennas (also known as adaptive array antennas, multiple antennas and MIMO) are antenna arrays with smart signal processing algorithms used to calculate beamforming vectors, e.g. to track and locate the antenna beam on the mobile/target. Smart antenna techniques are used extensively in modern radar, radio astronomy, and cellular systems (like W-CDMA and UMTS).
This “Smart antennas and Propagation” course aims to bring the student to understand the key aspects of (smart) antenna theory, design and measurement techniques (including practical hands on laboratory exercises) as well as fundamental factors involved in propagation in radio channels.
The learning objectives for this course are:
1.Students shall be able to explain the basics of antenna theory, antennas and smart antenna systems in the context of present-days academic, knowledge and commercial environment;
2.Students shall be able be to explain in detail the behavior of radio-wave propagation at radio and microwave frequencies;
3.Students shall be able to discuss in detail the system aspects of array and phased antennas, based on the theory and practical hands on exercises on radar systems and radio astronomy observations instruments;
4.Students shall be able to apply the knowledge to original and therefore possibly non-representative, academic-style problems;
5.Students shall be able to understand advanced analyses of others which may be met in the literature and in practical aspects of building and deploying antennas;
6.Students shall be able to design an antenna system, including the shape of the antennas, feed property, the requirement on the arrangement of the radiating elements in an array, given the radiation parameters such as radiation pattern, gain, operating frequency, transmit/receive power;
Course content
Antenna theory
•Antenna fundamentals - Overview of antennas and main characteristics, Electromagnetic wave propagation, Maxwell’s equations, Poynting Vectors, Hertzian Dipole.
•Antenna parameters – Isotropic radiators, Spherical Coordinates, Effective Area/Aperture, Gain, Directivity Link Budget, Impedance, Return Loss, VSWR, Polarisation, Radiation Resistance, Far Field Criteria, Beamwidth, Near/Far relations, Reciprocity, SAR.
•Microwave basics – transmission line equations, network analysis, passive microwave devices, filter essentials.
•Small Antenna design – wire antennas, microstrip antennas, aperture antennas, antennas for mobile applications, broadband antennas.
•Typical examples of different types of antenna and their principles of operations.
Array and phased antennas
•Arrays – linear arrays, planar arrays, patterns, beamsteering, grating lobes, non-uniform weights.
•Beamforming architectures and quantization effects.
•RF aspects – mutual coupling, computational techniques, radiating elements, calibration.
•Radomes
Propagation Principles
•Free space propagation.
•Polarization in a propagation environment.
•Reflection – Specular reflection. Fresnel coefficients, polarization effects. Rough and random surfaces.
•Refraction – Refractive index. Snell’s Law. Fresnel Transmission Coefficients.
•Diffraction – Huygen’s Principle. Knife-Edge Diffraction. Fresnel Zones
Propagation Models
•Path Loss: Free space loss. Plane earth loss. Spherical earth effects.
•Path profiles – Line of sight and non-line of sight.
•Review of link budget calculations – Maximum acceptable path loss, noise.
•Fast Fading aspects – statistics.
•Shadowing – Statistics.
•Antenna interaction in the environment
Laboratory
•We will try to do lab exercises at the Westerbork Synthesis Radio Telescope
Study material
We use the following book:
Constantin A. Balanis, Antenna Theory, 3rd edition, Wiley, 978-0-471-66782-7
