An Introduction to RF and Microwave Front Ends
Perhaps more importantly, the analogue interface to the EMS is more important than ever before despite – or more likely, because of – the fact that we live in a digital age. This course will give attendees an introduction to the most important properties of electromagnetic waves and consider the analogue components used to interface between the EMS and electronic systems (RF and microwave front ends). The presentation will build up to a consideration of the front-ends of some common systems including laboratory equipment and EW systems. In this way, the influence of basic EM theory, and RF and microwave components on the performance of systems exploiting the EMS will be explained.
Full Course: $1600 for members / $1650 for non-members
Individual Sessions:$250 for members / $300 for non-members
Session 1 – Basic Electromagnetic Theory
Basic electromagnetic (EM) theory necessary to understand the concepts considered later in the course will be presented. The exposition will include such fundamental concepts as wavelength, propagation velocity, reflection, refraction, transmission lines, S-parameters, and VSWR.
Session 2 – Propagation
The atmosphere can have a dramatic effect on EM waves propagating through it. Anomalous effects such as rain, ducting and multipath can have serious negative effects on system performance and thus need to be understood to ensure systems are used to their full potential. On the other hand, systems such as HF links and weather radars inherently rely on the properties of propagation through the earth's atmosphere to function, making an understanding of the relevant propagation mechanisms crucial. Important propagation mechanisms such as multipath and issues such as absorption and scattering will be presented with the emphasis on their effect on EW systems.
Session 3 – Antennas
Antennas form the interface between propagating EM waves and the systems which exploit those EM waves. As a result, the performance of a system is strongly influenced by the properties of the system antennas. Fundamental concepts such as gain, directivity, beamwidth, impedance bandwidth, radiating bandwidth, and sidelobes will be described and illustrated by considering examples of a number of widely-used antenna types.
Session 4 – Mixers and Filters
Amplifiers are necessary throughout any system to improve sensitivity, boost the signal level and provide high-power outputs. As a result of their many uses, the properties of amplifiers dominate many aspects of system performance, and many measures of system-level performance arise largely as a result of the properties of the relevant amplifiers. The basic properties of amplifiers such as gain, noise figure and output power will be described, along with how system-level performance is influenced.
Session 5 – Mixers and Filters
Most systems require some form of frequency translation, usually to convert high-frequency signals to the lower frequencies at which digital systems operate. Frequency-conversion devices such as mixers, frequency multipliers and dividers will be considered to illustrate the issues surrounding their use. Most frequency-conversion devices have outputs which contain both desired and undesired frequency components, so filters are necessary to suppress the unwanted frequency components. The operation of filters and their main parameters such as bandwidth and out-of-band suppression will also be considered. The interaction between frequency-conversion devices and filters will thus be highlighted as the other major driver of system-level performance along with amplifiers.
Session 6 – Oscillators and Synthesizers
Reference signals which are significantly higher than is possible with digital technologies are required to allow operation at RF and microwave frequencies. The necessary high-frequency signals are generated by a combination of oscillators and synthesizers. The most important properties of signal-generating systems will be considered with the emphasis on their influence on the performance of real-world systems.
Session 7 – Communications Jamming
June 7 - 1300-1600 EDT (1700-2000 UTC)
This session covers the theory and practice applicable to jamming both conventional and LPI communications signals. It first covers the jamming of conventional analog and digital signals. This includes approaches to determination of jamming effectiveness. Then, this session moves on to the jamming of LPI (frequency hopping, chirp and direct sequence spread spectrum) signals. Techniques covered include both those that can be used in fairly simple systems and those requiring sophisticated digital receivers and processors. Exercises leading to the determination of achieved jamming to signal ratios with various modulations and tactical situations are included.
Session 8 – Communications Intercept
June 9 - 1300-1600 EDT (1700-2000 UTC)
This session starts by covering the requirements to recover the information carried by conventional hostile communication signals in various tactical situations. This includes the calculation of effective ranges and the impact of modulations. The effect of various electronic protection techniques that can be applied by hostile communicators will be discussed. Also, this session will cover encryption and (in general) the approaches to defeating it. Finally, techniques for the recovery of information from (unencrypted) frequency hopping, chirp and direct sequence signals will be presented.
Warren du Plessis received the B.Eng. (Electronic) and M.Eng. (Electronic) and Ph.D. (Engineering) degrees from the University of Pretoria in 1998, 2003 and 2010 respectively, winning numerous academic awards including the prestigious Vice-Chancellor and Principal's Medal. He has been working in EW and radar since 2006 and is currently Associate Professor at the University of Pretoria. Warren is a Senior Member of the Institute for Electrical and Electronics Engineers (IEEE), a Lifetime Member of the Association of Old Crows (AOC), and a member of the AOC Aardvark Roost Board. He is author of 46 published and accepted peer-reviewed journal and conference papers, and is lead or sole author of 30 of these. While best known for his work on cross-eye jamming, Warren has also published in a number of other fields related to EW including thinned antenna arrays, communications intelligence (COMINT), and the role of EW and its relationships to other similar fields.
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