Composite Patch Array Antenna with Built-In Polarizer and Its Road Clutter Reduction Effect for 76 GHz Automotive Radars

Hiroshi SHINODA  Hiroshi KONDOH  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E92-C   No.11   pp.1401-1405
Publication Date: 2009/11/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E92.C.1401
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Microwaves, Millimeter-Waves
Keyword: 
patch array antenna,  polarizer,  RF absorber,  road clutter,  automotive radar,  

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Summary: 
A composite patch array antenna with built-in polarizer has been developed to reduce road clutter noise by 20 dB for 76 GHz automotive radars. A polarizer is placed in front of Tx and Rx patch arrays within their reactive near-field region to suppress cross-polarized sidelobe radiation from their feeding lines while maintaining a low-profile characteristic with 4 mm thickness. Additional metal-lined absorbers within the composite antenna structure, while terminating cross-polarized waves undesirably excited by the patch arrays, also serve as miniature clutter plates to further reduce sidelobes toward the road surface. The resultant composite antenna achieved sidelobe levels of -45 dB, a 20 dB improvement over standard patch arrays, at elevation angles close to 90.