Optical True Time-Delay Feeder for X-Band Phased Array Antennas Composed of 2<tex>$,times,$</tex>2 Optical MEMS Switches and Fiber Delay Lines

Abstract

We proposed an optical true time-delay (TTD) feeder for X-band linear phased array antennas (PAAs), which possesses high-speed beam scan capability by selecting different lengths of fiber delay lines with fast 2 2 optical microelectromechanical system switches. For proof of concept, a 3-bit optical TTD has been built for a 10-GHz linear PAA composed of two antenna elements. Experimental results show that the maximum time-delay error is less than 0.2 ps, corresponding to a radiation angle error of less than 0.84 , which is within the equipment resolution. We have also designed a 10-GHz linear PAA composed of eight microstrip patch antenna elements driven by the proposed TTD. The radiation patterns of this PAA have been obtained by simulation.Index Terms-Beam forming networks, optical microelectromechanical system (MEMS), phased array antennas (PAAs), true time-delay (TTD).

Demonstration of a quartic cell, a free-space true-time-delay device based on the white cell

“…Another polynomial cell design is the octic cell [25], [26], with N proportional to b 8 . One implementation of the octic cell is two orthogonal quartic cells, and one of these quartic cells was demonstrated previously [25].…”

“…These typically use 1 × 2 switches to switch optical beams between planar waveguides of different lengths. Fibers of different lengths were also used early on [4]- [8]. These approaches in general require a series of delay lines for each antenna element or a single fiber for each delay and switching of beams among them.…”

Photonic True-Time Delay for Phased-Array Antenna System using Dispersion Compensating Module and a Multiwavelength Fiber Laser

“…The techniques other than these are based on optical phase shifters [9], switchable delay matrices [10][11][12][13][14], liquid crystal polarization switching devices [15], a combination of a wavelength-tunable laser and a dispersive optical element, such as a high dispersion fiber [16,17], a fiber optic prism [18,19], a fiber Bragg gratings (FBGs) prism [20][21][22], or chirped FBGs [23][24][25][26][27].…”

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

“…Compared with all-electrical techniques, optical true-time delay generation offers the advantages of broader bandwidth, lower insertion loss, higher phase stability, smaller size, lighter weight, and excellent immunity to both electromagnetic interference and crosstalk [2][3][4][5]. 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]. However, 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].…”