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1 June 1990 Integrated optical Butler matrix for beam forming in phased-array antennas
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Butler matrices, consisting of 3 dB directional couplers and phase shifters, can be used to obtain specific phase relationships between the signals on the feedlines of the various antenna elements in a phased array system. Microwave Butler matrices consisting of microwave phase shifters and directional couplers are difficult to fabricate because of crosstalk and EMI. Integrated optical Butler matrices, in addition to being immune to EMI and having negligible cross talk, are small in size, lightweight and can be fabricated on a single substrate. Some of the advantages of using an integrated optical Butler matrix for beam steering and detection in a phased array system are discussed. Integrated optical directional couplers are fabricated on LiNbO3 substrates by a proton exchange and thermal annealing technique. A method of obtaining accurate 3 dB directional couplers is presented. Statistics based on the experimental measurements of these directional couplers are used to demonstrate the relative insensitivity of the Butler matrix performance to variations in fabrication parameters. The S/N and dynamic range of a sysem employing a Butler matrix with an optical local oscillator are calculated and compared to present-day phased-array antenna systems.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Walter Charczenko, Marc R. Surette, Paul J. Matthews, Holger Klotz, and Alan Rolf Mickelson "Integrated optical Butler matrix for beam forming in phased-array antennas", Proc. SPIE 1217, Optoelectronic Signal Processing for Phased-Array Antennas II, (1 June 1990);

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