Accession Number : ADA327836

Title :   Low-Loss Fiber-Optic True Time Delay Generator for RF Signal Processing and Phased Array Antenna Control (TTD).

Descriptive Note : Final technical rept. Nov 94-Oct 96,

Corporate Author : TRW SPACE AND ELECTRONICS GROUP REDONDO BEACH CA

Personal Author(s) : Wickham, Michael ; Dozal, Larry ; Brock, John

PDF Url : ADA327836

Report Date : JUN 1997

Pagination or Media Count : 55

Abstract : The work established the viability of a fiber-optic approach for low-loss true time delay of wideband RF signals for phased-array antenna (PAA) beamsteering. In this approach an optical carrier modulated by the RF signal of interest is launched into a delay-line fiber composed of optical Bragg reflection gratings written holographically into the core of a single-mode fiber. The beam is steered by tuning the optical carrier wavelength for reflection from the appropriate grating. The fiber Bragg grating writing performance meets and exceeds PAA requirements. We demonstrated: (1) a time delay accuracy of approximately 2 ps (20 Ps verified); (2) a wavelength writing accuracy for Bragg gratings of 0.04 microns absolute, 0.01 nm relative; (3) a sidelobe suppression of 50 dBe at 2 nm channels and 60 dBe at 3 nm channels. We produced a 4-bit, 16 grating true time delay element which includes an optical circulator. An analytical model, which includes chirp, was developed that predicts both the optical and RF response for the fiber optic Bragg grating.

Descriptors :   *FIBER OPTICS, *ANTENNA ARRAYS, SIGNAL PROCESSING, OPTICAL WAVEGUIDES, GRATINGS(SPECTRA), LOW LOSS, HOLOGRAPHY, BROADBAND, OPTICAL PROCESSING, BEAM STEERING, RADIOFREQUENCY, SIDELOBES, PHASED ARRAYS, DELAY LINES, RADIOFREQUENCY PULSES, TIME LAG THEORY.

Subject Categories : Electrical and Electronic Equipment
      Fiber Optics and Integrated Optics
      Electrooptical and Optoelectronic Devices

Distribution Statement : APPROVED FOR PUBLIC RELEASE