Why UWB Antennas: UWB Signals and UWB Frequency Range
Ultra-wideband (UWB) signals are impulse-type signals which are localized
in time but spread out in frequency. In order to transmit or receive such
UWB signals, time non-dispersive ultra-wideband antennas are required. Ultra-wideband antennas
(UWB antennas) thus enable future-proofing, in that they can transmit and receive ultra-wideband signals.
Ultra-wideband also refers to a broad frequency range encompassing many narrowband
frequencies (signals which are not localized in time and thus which have long duration but narrow frequency),
which requires UWB antennas to transmit and receive throughout all narrowband frequencies in the range.
UWB antennas thus also enable covering the entire frequency range with a single antenna.
UWB antennas
enable the user to achieve a lower visual profile, lower radar profile (low radar cross section, or RCS),
and a lower space and weight requirement on the platform. Using a single UWB antenna also makes it
simpler to integrate the antenna in the system and to conduct any periodic updates or maintenance.
Therefore, UWB antennas can combine performance and operational benefits, with improved total
cost/time/space/weight efficiency for military antenna applications.
UWB Antenna Concepts
The basic principle of an antenna, including a UWB antenna, is that it
converts energy from a cable, into energy that propagates outward through
the air, as free space propagating electromagnetic waves.
This energy may be focused in a particular direction (and hence the antenna is a directional antenna),
or it may transmit uniformly in all directions (and hence the antenna is an omnidirectional antenna).
Therefore, both directional UWB antennas and omnidirectional UWB antennas can be produced.
The key definition of an UWB antenna is that the frequency range of the antenna,
meaning the range in which the antenna has a voltage standing wave ratio (VSWR)
< 3, has a ratio of 10:1 between the maximum frequency and the minimum frequency.
Therefore, a UWB antenna will typically cover a 10 to 1 f-max, f-min frequency range with VSWR of less than 3 throughout.
Military Applications for UWB Antennas
UWB antennas provide significant advantages for military operations, in minimizing
system complexity, size/weight, maintenance/integration time and hence potentially also reducing
total system cost. UWB antennas also minimize the platform’s visual signature and radar signature
(RCS), and thus improve mission effectiveness and covertness. UWB antennas could play an increasingly
prominent role in military applications, such as tactical communications and information warfare.
