Electronic warfare (EW) inherently deals with the electromagnetic spectrum (EMS). As a result, an understanding of the EMS and how electronic systems interface with the EMS is essential for all EW practitioners.
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.
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Session 1: Basic Electromagnetic Theory
August 1 | 1300 - 1600 EDT (17:00-20:00 UTC)
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
August 3 | 1300 - 1600 EDT (17:00-20:00 UTC)
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
August 8 | 1300 - 1600 EDT (17:00-20:00 UTC)
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: Amplifiers
August 10 | 1300 - 1600 EDT (17:00-20:00 UTC)
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
August 15 | 1300 - 1600 EDT (17:00-20:00 UTC)
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 Synthesisers
August 17 | 1300 - 1600 EDT (17:00-20:00 UTC)
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 synthesisers. 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: Miscellaneous Components
August 22 | 1300 - 1600 EDT (17:00-20:00 UTC)
A wide range of components which are useful in real-world systems, but which do not fall under the categories of previous lectures, also exists. While not necessarily as fundamental to the operation of systems as amplifiers, mixers, filters and oscillators are, they nevertheless provide important functionality. Examples of the components which will be considered are isolators, circulators, switches, couplers, splitters, combiners, phase shifters, attenuators and limiters. The main characteristics, properties and applications of each of these components will be outlined.
Session 8: System Examples
August 24 | 1300 - 1600 EDT (17:00-20:00 UTC)
The material covered in the course will be summarised by showing how real-world systems are constructed. Examples will include laboratory instruments such as oscilloscopes, spectrum analysers and network analysers as these are well-known and widely-used systems. A DRFM front-end will also be considered as a representative example of an EW system.