Patent ID: 7408507
Filing Date: 2008-08-05
Classification: H01Q

Abstract:
1. A method of calibrating a phased array antenna housed within a radome, comprising: a) providing an optical timing signal generator (OTSG) having a DFB laser source for generating an optical calibration signal, a modulator for modulating the light calibration signal and generating a modulated optical output signal, and a Variable Optical Amplitude and Delay Generator array (VOADGA) for receiving the modulated optical output signal and generating a plurality of VOADGA timing signals, and an optical timing signal distributor (OTSD) housed within the radome for receiving the plurality of VOADGA timing signals, the OTSD having a matrix-addressable PLC having N horizontal waveguides and N vertical waveguides for receiving the VOADGA timing signals, said wave guides having a plurality of intersections, each intersection having a photodiode positioned thereon for receiving a portion of the VOADGA timing signals and for generating a proportional electrical output signal for subsequent processing and calibrating of the phased array antenna; b) optimizing RF delays to compensate for PLC delays, line-by-line; c) aligning VOADGA delays so that incoming input signals have the same phase at the entrance of the matrix; d) adding linear chirp delays to VOADGA to steer beam directions; e) optimizing RF delays to match the additional VOADGA delays and record the RF delay values to form a look-up-table (LUT); f) repeating steps d)-e) for all the beam positions along the azimuth and elevation directions; g) adding additional linear chirp delays to the VOADGA to scan through the beam pattern and to estimate sidelobes; and h) then tapering RF amplitudes in the RF front-end of the phased array antenna to minimize the sidelobe level.