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3-MM Wave Fast Scanning Antenna

Many of millimeter wave radar systems require very fast antenna beam scanning. For example, in collision
avoidance radars it is necessary to update radar data every 12 second. It means that the radar beam velocity
should not less than 2000 degrees/second if we would like to have angular scanning zone approximately 120
degrees in azimuth and 20 degrees in elevation. The best possible way to do this are electrically steering antenna
beam arrays: phase antenna arrays, or frequency steerable antenna beam arrays. Unfortunately, today the
mentioned antenna beam steering methods are impossible at frequencies in short mm waves. Another reason is
rather high cost of these technologies. Because designers of low cost navigation and collision avoidance radars are trying to find how to do the same in more simple way using mechanically steerable mmw antenna beam .

LRERI has designed the 3-MMW fast scanning antenna for a compact search radar, for example, collision avoidance radar for low flying light aircrafts and helicopters or close range navigation radars.

The antenna is so called inversed Cassegrainian antenna type, that is antenna, having two reflectors- stationary
parabolic reflector and lightweight flat twist reflector.
The proposed idea to do fast antenna scanning (antenna beam velocity up to 2000 deg/sec) is to convert continuous rotary motion of electric engine (effector) into oscillatory motion of the flat twist reflector.
If we could do parameters twist reflector positioning gear matched to inertia oscillations of the twist reflector, the
gear power would be very low in comparing to classical method. To do it we have to adjust appropriately
parameters of the digital regulator. The work has been done using mathematical modeling.
The mathematical model of the positioning gear was developed and analyzed using MATHCAD and appropriate
proproduction model of the antenna have been fabricated and tested.
 

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