Patent ID: 6388616
Filing Date: 2002-05-14
Classification: G02B,H01Q

Abstract:
A true time delay generator for optical control of a phased array antenna system having an array of antenna elements arrayed in a first dimension and a second dimension and having a number N of antenna elements in said first dimension and a number M of antenna elements in said second dimension, said generator comprising:(a) first time delay means for providing a time delay for optical control of said phased array antenna system in said first dimension, said first time delay means for guiding a set of input light beams corresponding to said number N of antenna elements in said first dimension to provide an output comprising a first series of light beams, N in number, delayed relative to one another with an equal amount of time delay in said first dimension between each two consecutive light beams of said first series of light beams; (b) splitter means for splitting each light beam of said first series of light beams to provide an output comprising N groups of M light beams; (c) second time delay means for providing a time delay for optical control of said phased array antenna in a second dimension, said second time delay means for guiding said output of splitter means to provide an output comprising said N groups of M light beams in which said M light beams in each one of said groups are delayed relative to one another to have an equal amount of time delay between each two consecutive light beams in said each one of said groups in said second dimension, said N groups of light beams constituting signals for subsequent opto-electric conversion for steering a propagation direction of said phased array antenna; wherein said first time delay means comprises a delay generator unit and said second time delay means comprises N attached delay generator units, each of said delay generator units comprising: (i) first and second end walls disposed substantially parallel to each other and forming a cavity there between, the first end wall having a first plurality of mirrors formed thereon and the second end wall having a second plurality of mirrors formed thereon to face the first plurality of mirrors; (ii) an intermediate wall disposed between said first and second end walls and being substantially parallel thereto to form a first chamber and a second chamber in said cavity, said intermediate wall having a third and a fourth plurality of mirrors formed on opposite sides thereof to face respectively the first plurality of mirrors of said first end wall and said second plurality of mirrors of said second end wall, said intermediate wall having a series of apertures for passage of the input light beams from the first chamber to the second chamber; and (iii) displacement means for displacing one of (1) said intermediate wall relative to said first and second end walls and (2) said first and second end walls relative to said intermediate wall, so that an area of the first and second chambers is variable for changing a time delay of the optical path of the input light beams in the cavity.