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Multiple
antenna elements of a phased-array antenna are
fed with certain initial phases. The emitted electromagnetic waves
interfere with each other to achieve beam forming and beam steering.
By electronically adjusting the initial phases, the beam can be
scanned and shaped fast without physical movement. Furthermore,
this type of antenna can be applied to a multi-mode operation, having
simultaneous multiple steering beams that cover a large area. Having
so many advantages over the single antenna, phased-array antennas
are now widely used in both civilian operations, such as air traffic
control and broadcast satellite communications, and in the military
arena, such as marine radar, airborne radar, missile guidance, trajectory
determination, and satellite communications.
The traditional electrical phase
shifters for phased-array antennas are intrinsic narrow band, which
introduce the beam squint effect. True-time delay techniques can
solve the puzzle. Optical true-time delay techniques have the merits
of small, light weight, low loss, and immune to electromagnetic
interference. Our company is working on several optical true-time
delay techniques, including planar waveguide techniques, the fan-out
technique, etc.
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