Opto-VLSI-based photonic true-time delay architecture for broadband adaptive nulling in phased array antennas

Abstract

This paper proposes a novel Opto-VLSI-based tunable true-time delay generation unit for adaptively steering the nulls of microwave phased array antennas. Arbitrary single or multiple true-time delays can simultaneously be synthesized for each antenna element by slicing an RFmodulated broadband optical source and routing specific sliced wavebands through an Opto-VLSI processor to a high-dispersion fiber. Experimental results are presented, which demonstrate the principle of the true-time delay unit through the generation of 5 arbitrary true-time delays of up to 2.5 ns each.

Tunable true-time delay of a microwave photonic signal realized by cross gain modulation in a semiconductor waveguide

“…Since the demonstration of an optically steered phased array antenna in 1991, 1 the study of tunable microwave time delay lines realized by photonics has become a hot topic within the developing research area of microwave photonics. 2 A common scheme exploits dispersion, with the time delay being varied by tuning the laser wavelength and propagating through high dispersion fibers 3,4 or chirped fiber gratings. [5][6][7] This scheme is, however, relatively bulky and complex.…”

Photonic true-time delay unit for broadband adaptive nulling in antenna arrays

“…4. The free-spectral range (FSR) of the RF response is inversely proportional to the true-time delay between adjacent wavebands (Juswardy et al 2009) and the experimental results shown in Fig. 7 demonstrates the simultaneous generation of 7 wavebands with 1.8-4 nm separation between adjacent waveband, corresponding to an arbitrary inter-waveband true-time delay of 0.7 to 1.5 ns.…”

“…The diffraction (or steering) angle for an Opto-VLSI processor, α m , is given by Juswardy et al (2009):…”

“…Broadband null steering is the ability to maintain nulls at chosen angular coordinates for broad frequency range (Zmuda et al 1998;Juswardy et al 2009). Broadband null steering, however, requires a beamformer that can generate both variable and frequency independent true time-delays (TTD).…”

Opto-VLSI-based broadband true-time delay generation for phased array beamforming

“…Generally, for an N-element broadband phased array, the synthesis of (N-1) broadband nulls can be achieved if the beamformer of the antenna can adaptively generate and combine (2 N-1 -1) delayed versions of the RF signals received by the antenna elements [2] as illustrated in Fig. 1.…”