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Although satellites can be attacked kinetically, it is a great deal of
trouble to do so
June 2021 -- London -- Artech House has released a new book by well-known author
David L. Adamy entitled "EW 105 - Space Electronic
Warfare."
There is increasing interest in Electronic Warfare 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 electronic warfare platforms. A disadvantage of satellites
is that they are in general unmanned. This means that communication with a satellite
requires an electro-magnetic 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 vs. 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 one and a half hours and they only dwell for a few minutes over
one potential target, and can see out to about 2000 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 attitude is 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.
Orbital Relationships
After some important math related to satellites, we'll cover some basic relationships
in orbits. We will skip many of the niceties of derivations and minor details in
this book, but will go directly to the information required for us to work practical,
EW related problems – primarily intercept and jamming of hostile signals transmitted
from the Earth's surface and the vulnerability of satellite links to attack from
the Earth's surface. We will divide our attention between hostile radars and hostile
communications. The path of an Earth satellite is affected by the gravitational
pull of every other object in space, but most of those objects are far away and
thus have only secondary effects.
The main elements determining the orbit are the gravitational pull of the Earth
and the velocity of the Earth satellite.
By ignoring other factors, we have what is called the "two body problem." For
our purposes at this time, we assume there is nothing in space except the Earth
and one satellite moving around the Earth. Working with the mechanics of the orbit
and dealing with angles and distances between satellites and the transmitters and
receivers involved in EW operations will require the use of spherical trigonometry,
so we will also cover that rather gently – focusing on the equations required to
work EW problems. The other important math involves radio propagation. We will cover
this both within the atmosphere and in space.
A note about orbital calculations in this book
There is a lot of trigonometry in this book. This is because the inputs to electronic
warfare equations are very dependent on the relative positions of satellites and
ground transmitters or receivers. Also important to calculations are the relative
directions to other "players." When dealing with relationships in spherical and
plane triangles in problems presented in all of the chapters, it may seem that a
few things are "over explained." This is because the author (like many other people)
can get lost in the geometry and thus would prefer to over explain something than
to leave out logical steps that "seem obvious." This is done without apology.
About Artech House
A leading technical book publisher, Artech House provides today's professionals
and students with cutting-edge books and software from the world's top authorities.
From RF/microwave design, wireless communications, radar engineering, and electronic
defense, to GPS/GNSS, power engineering, computer security, and building technology,
Artech House publishes the forward-looking titles that engineers and managers need
to excel. Artech House is a subsidiary of Horizon House Publications, Inc., publisher
of the internationally acclaimed magazine Microwave Journal®. Artech House operates
two full service offices: the main headquarters in suburban Boston, and a European
division located in Central London. Both offices offer full publishing capabilities,
from sales and distribution, to acquisitions and editorial, to promotion and marketing
functions.
Contact:
Diana Cristea Artech House Order Department 16 Sussex Street London,
SW1V 4RW UK Phone: +44 (020) 7596-8761 Fax: +44 (020) 7630-0166
E-Mail:
artech-uk@artechhouse.com Internet:
www.artechhouse.com
Posted June 6, 2021
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