Accession Number : ADA318134
Title : Photonic True Time Delay Beamformer for a 20 Element L-Band Phased Array,
Corporate Author : ROME LAB ROME NY
Personal Author(s) : Payson, Paul M. ; Malowicki, John E. ; Klumpe, Herbert W., III ; Toughlian, Edward N. ; Zmuda, Henry
PDF Url : ADA318134
Report Date : OCT 1996
Pagination or Media Count : 111
Abstract : A phased array is a directive antenna made up of individual radiating elements which generate a radiation pattern whose shape and direction are determined by the relative phases and amplitudes of the currents at the individual elements. Current state of the art phased array radars implement electronic phase shifters for beamforming. The limitation of the phase shifters becomes apparent if multiple frequencies are transmitted simultaneously. The energy associated with the different frequencies will point in different directions in the antenna's far field causing an increase in beamwidth. This phenomena, called squint, restricts the phase shift approach to narrowband operation. A trne time delay line based on an optical heterodyning technique is used to generate properly phased signals enabling wide bandwidth operation. The theory, design, development, testing and analysis for photonically controlling a 20 element, wide bandwidth (200 MHz) L Band phased array radar are presented.
Descriptors : *BEAM FORMING, *OPTICAL PROCESSING, *PHASED ARRAYS, TIME INTERVALS, HETERODYNING, FAR FIELD, PHOTONICS, OPTICAL CIRCUITS, RADAR ANTENNAS, ANTENNA RADIATION PATTERNS, NARROWBAND, DELAY LINES, PHASE SHIFT CIRCUITS, L BAND, SQUINT MODE.
Subject Categories : Radiofrequency Wave Propagation
Electrooptical and Optoelectronic Devices
Active & Passive Radar Detection & Equipment
Distribution Statement : APPROVED FOR PUBLIC RELEASE