F- k Filter Designs to Suppress Direct Waves for Bistatic Ground Penetrating Radar Hayashi, Naoki ; Sato, Motoyuki Abstract Publication: IEEE Transactions on Geoscience and Remote Sensing Pub Date: March 2010 DOI: 10.1109/TGRS.2009.2032536 Bibcode: 2010ITGRS..48.1433H