Synthesized shaped beam flat array antenna for digital beam-forming radar applications, utilizing printed technology

摘要

An implementation of a X-band flat array antenna with a synthesized shaped beam in the elevation plane and a digital beam forming (DBF) capability in the azimuth plane is presented. The shaped beam synthesis has been implemented on an array excitation level, the theory used for it is based on the Fourier transform method. The criteria for the synthesis have been selected in such a way, so to widen and change the roll-off slope steepness of the array main beam in elevation plane as well as to suppresses the sidelobes. The necessary magnitude and phase distribution for the synthesized beam are integrated within the corporate feed network of the array, which is printed on a low loss planar substrate. An additional beamshaping, achieved by means of electromagnetic band gap like structures for the transmitting part of the antenna has been demonstrated as well. The DBF capability of the array in the azimuth plane secures a field-of-view of 90 deg at a grating lobe level below -50 dB. The array makes use of an innovative, open-ended waveguide-like, broadband radiating element, electromagnetically coupled to the array feeding network. Thanks to the corporate feed and to the features of the radiating element, the array exhibits a wide instantaneous bandwidth of more than 30% in X band at a VSWR 2:1. A good compliance between simulated and measured performances of the array is presented and discussed.