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US 5,144,321 AGranted
Method device and microwave antenna system for applying discrete delays to a signal
AssigneeAlcatel
InventorMichel Biet
Life of this patent
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Abstract
A digitally controlled delay is applied to a microwave signal by applying the signal to a transmitter to modulate an optical wave which is transmitted by polarization holding optical fibers after its polarization is switched in TE or TM mode in switching units. An optical receiver reconstitutes a delayed microwave signal. Variation of the delay is controlled by delay select signals controlling the switching units. The principle finds particular application in phased array antenna systems.
Claims6
Device for applying discrete delays to a signal, said device comprising at least one delay switching stage, each said switching stage comprising:
- a delay unit adapted to receive an optical wave conveying
- an input signal to be delayed and to apply to said wave a stage delay having selectively either a high value or a low value, and
- a switching unit adapted to receive a delay select signal appropriate to said stage and to be responsive thereto by controlling the delay applied by said delay unit so that said optical wave after passing through said switching stage conveys a stage output signal having said stage delay relative to said input signal, wherein
- said delay unit incorporates a single optical delay line in the form of a polarization holding optical fiber having two principal transverse directions constituting a slow direction and a fast direction so that two optical waves at the same frequency polarized in said slow and fast directions propagate in said fiber with respective relatively low and relatively high velocities, and
- said switching unit comprises at least one polarization switch at the input of said optical delay line and controlled by said delay select signal to polarize said optical wave in said slow direction or said fast direction of said fiber and thereby to assign to said stage delay either said high value or said low value, respectively.
2 more elements
Phased array antenna system comprising:
- an array of antenna elements adapted to transmit to or receive microwave radio waves and respectively to receive or to supply respective microwave electrical signals corresponding thereto,
- a central circuit adapted to transmit or to receive said microwave electrical signals to or from respective antenna elements, and,
- a respective composite line for each antenna element adapted to transmit a microwave electrical signal between said antenna element and said central circuit, each composite line comprising a delay device adapted to apply a selective delay to the electrical signal carried thereby, wherein
- each said delay device applies discrete delays to a signal and comprises at least one delay switching stage, each said switching stage comprising:
- a delay unit adapted to receive an optical wave conveying an input signal to be delayed and to apply to said wave a stage delay having selectively either a high value or a low value, and
- a switching unit adapted to receive a delay select signal appropriate to said stage and to be responsive thereto by controlling the delay applied by said delay unit so that said optical wave after passing through said switching stage conveys a stage output signal having said stage delay relative to said input signal, wherein
- said delay unit incorporates a single optical delay line in the form of a polarization holding optical fiber having two principal transverse directions constituting a slow direction and a fast direction so that two optical waves at the same frequency polarized in said slow and fast directions propagate in said fiber with respective relatively low and relatively high velocities, and said switching unit comprises at least one polarization switch at the input of said optical delay line and controlled by said delay select signal to polarize said optical wave in said slow direction or said fast direction of said fiber and thereby to assign to said stage delay either said high value or said low value, respectively.
4 more elements
Dependencies are inferred from the claim text.