Ew 105: Space Electronic Warfare

Book Preface

This book deals with the intersection of two disciplines: electronic  warfare (EW) and satellites. It is written in the hope that it will be useful to those who are EW professionals but know little about satellites  or who are satellite professionals but know little about EW. It is also  designed to be useful to those who are new to both. EW is very real  in space. There are many satellites that are vital to both military and  civil activities. Many are under current electronic attack, and the rest  are vulnerable to attack that may not yet have occurred.

There is an appendix on EW basics and chapters on the basics of  spherical trigonometry, orbit mechanics, and radio propagation. This  book deals with specific kinds of problems that must be solved. What  does it take to intercept a hostile signal from space? What does it take  to jam a hostile signal from space? What can an enemy do to keep our  satellite from doing its job and what can be done to protect our satellite from that enemy activity?
This book takes a cookbook approach to the description of problems that those in the conduct of space EW may be called upon to  solve. Step by step, how can you prepare the desired dish? Each problem is described in terms of the physical nature of the situation. Then  an example is presented to show generically the way to determine the required answers. Numbers are plugged in to get numerical answers.
The idea is that when you are called upon to solve a real-world problem, you can plug the real-world specifications into the equations  to get the required real-world answers. This requires that we wade  though some spherical trigonometry, but that is the nature of space
EW, and the answers that we get can be a matter of life or death.

There is increasing interest in electronic warfare (EW) in space because of the strategic advantages that satellites offer. Because of their  elevated positions, they can see a great distance, and they can remain  operational for extended periods. Although satellites can be attacked  kinetically, it is a great deal of trouble to do so; they are small and far  away. This makes them valuable as EW platforms.
A disadvantage of satellites is that they are in general unmanned.

This means that communication with a satellite requires an electromagnetic link which is vulnerable to enemy countermeasures. Another disadvantage of a satellite is that it cannot be easily steered to an  optimum location. However, we can predict the timing versus satellite location, so we can plan other events with full knowledge of when  a satellite will be able to view a part of the Earth’s surface.  In general, the higher a satellite is, the longer it can see a specific part of the Earth. Low orbits, barely above the atmosphere, have  orbital periods down near 1.5 hours and they only dwell for a few  minutes over one potential target, and can see out to about 2,000 km  from the sub-vehicle point (the sub-vehicle point is on the Earth right  below the satellite). When a satellite is at about 37,000 km altitude, it  has an orbital period of 24 hours, so it can hover over one location indefinitely and can see about 45% of the Earth’s surface. This is called  a synchronous orbit. We will deal with the calculation of these and  related values for specific satellite parameters in later chapters

A major trade-off in the selection of satellite orbit parameters is  the range between the satellite and a potential target for intercept or  jamming. As stated above, satellites are far away and thus incur very  large signal transmission losses.