What is Direction-Finding (DF)?
Direction-finding is one of the three primary tasks in information warfare. Specifically, information warfare consists of:
Signals intelligence (SIGINT)
Direction-finding (DF)
Electronic attack (EA)
These can be thought of as "listen, locate and respond", as follows:
Listen: In signals intelligence, the objective is to monitor the environment for signals of interest and collect the signal information.
Locate: In direction-finding, the objective is to determine the direction that the signal of interest is coming from.
Respond: In electronic attack, the objective is to jam the signal of interest.
Antennas for Direction-Finding
Direction-finding requires the ability to cover all angles from which the signal could be arriving, and
to be able to receive over a wide range of frequencies (as the adversary may be changing the frequency at which signals are transmitted).
A direction-finding antenna should ideally be ultra wideband and time non-dispersive.
An ultra wideband antenna can receive signals from (or transmit signals to) a wide range of narrowband
frequencies, meaning a frequency range ratio (maximum frequency divided by minimum frequency) of 10:1 or better.
A time non-dispersive antenna can receive and transmit impulse type signals (true ultra wideband signals)
and thus is future-proof against emerging threats. Hence, an ideal direction-finding antenna will be an ultra wideband, time non-dispersive antenna.
To cover all azimuth angles (from which the signal may be emanating), one should use an ultra wideband,
time non-dispersive antenna array. An antenna array is a set of individual antenna elements
(usually directional antenna elements), arranged in a circular pattern (sometimes with an omnidirectional element),
in a single enclosure. The circular arrangement of the elements means that the directional elements point in
different directions, to pinpoint the direction of signal origin most effectively.
Direction-finding antennas and arrays can be made very lightweight and compact, and can often be customized to the user’s requirements.
Summary/Conclusions
Direction-finding is an increasingly important part of military operations, as it provides the ability to
locate the direction that an adversary is transmitting signals from. High performance antennas and arrays
can be used to make direction-finding most robust and effective. Ultra wideband, time non-dispersive,
high performance ultra-lightweight direction-finding arrays are particularly useful and can be viewed
as a mission critical technology for information warfare.
