Military Omnidirectional Antennas: Selecting the Best Antenna for your Application
Military omnidirectional antennas are used in a wide range of applications, from tactical communications
to information warfare applications (such as SIGINT or direction-finding, for example). In tactical communications,
the objective is to transmit and receive signals between platforms (or ground-based operators) in the field.
In signals intelligence (SIGINT), the objective is to monitor the environment for signals of interest and
collect the signal information. In direction-finding (DF), the objective is to determine the direction that the signal of interest is coming from.
An omnidirectional antenna is an antenna which transmits with approximately equal gain in all directions in the horizontal
(azimuth) plane, which is useful for receiving signals from (and transmitting to) all directions. In tactical communications,
this is useful for transmitting in all directions, and receiving signals from all directions. In SIGINT, this allows for
more complete monitoring of the environment for signals of interest. In DF applications, the use of an omnidirectional
antenna or omnidirectional element (in the case of an antenna array) assists in determining the direction of origin.
Military omnidirectional antennas are often designed to be ultra wideband. An ultra wideband antenna is defined as an antenna
which has a voltage standing wave ratio (VSWR) < 3 throughout a frequency range who ratio of maximum frequency to minimum frequency
(fmax/fmin) is >= 10. Hence an ultra wideband military omnidirectional antenna can receive or transmit narrowband signals across
a very broad frequency range. A further advantage is that a time non-dispersive ultra wideband military omnidirectional
antenna can transmit or receive impulse-type (true ultrawideband) signals, and is thus able to handle emerging threats.
The further advantageous performance features that one should look for when selecting the best military omnidirectional
antenna include low visual profile and low radar cross section (RCS) to reduce the radar profile
of one's platform and thus make it more difficult for adversaries to detect. A high performance military
omnidirectional antenna should also have gain increase with frequency and consistent circular (omnidirectional)
radiation patterns. On many weight-sensitive platforms, such as aircraft/UAVs, team-transportable or man-portable,
the right military omnidirectional antenna should be light-weight, and on any platform (air, land or sea, including ground
vehicles, surface ships, submarines, etc) the antenna should be rugged and require no peripherals such as baluns,
ground planes or impedance transformers. With basic information on the available space (cylinder volume) and weight
for the antenna, often a custom military omnidirectional antenna can be produced around the end-user's requirements.
