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

Budi Juswardy,Kamal Alameh,Feng Xiao

doi:10.1364/oe.17.004773

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 RF-modulated 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.

Highlights

The processing of radio frequency (RF) and microwave signals in the optical domain is an attractive approach to overcome the bottlenecks of bandwidth, power losses, and electromagnetic interference (EMI) encountered in conventional electronic signal processing systems [1]
The use of photonics-based true time delay units to realise adaptive broadband phasedarray antenna (PAA) beamformers has extensively been investigated in the last decade for applications ranging from modern microwave radar to wireless communication systems
Broadband microwave phased-array antennas require the generation of variable true-time delays at each antenna element to realize beam or null steering, and optical fibers have been the best candidates for true-time delay synthesis

Summary

Introduction

The processing of radio frequency (RF) and microwave signals in the optical domain is an attractive approach to overcome the bottlenecks of bandwidth, power losses, and electromagnetic interference (EMI) encountered in conventional electronic signal processing systems [1]. Several approaches have been adopted to realise tunable true-time delay units, including the use of in-fiber chirped Bragg gratings (FBGs) [3], white cells or fiber delay lines in conjunction with MEMS [6,7,8,9], integrated optical waveguides [10], optically-switched fiber delay structures [11], dispersionenhanced photonic-crystal fibers [12], and higher-order mode dispersive multi-mode fibers [13] While these reported true-time delay architectures have been efficient for realising beam steering in phased array antennas, they do not have the flexibility to simultaneously generate multiple arbitrary true-time delays, and this makes them impractical for broadband null steering [14]. This true-time delay unit has the capability to generate multiple true-time delays for several antenna elements simultaneously, making it attractive for broadband null-steering in phased array antennas

Opto-VLSI processor

Phased-array antenna architecture for broadband null steering

Experimental setup

Conclusion