EFFICACY OF AN S-SHAPED AIR INLET ON THE REDUCTION OF FRONT BISTATIC RADAR CROSS SECTION OF A FIGHTER ENGINE

Abstract

The engine of a fighter plane is one of the largest scattering centers of the entire aircraft. One possible way of reducing the radar cross section (RCS) of the engine is to use an S-shaped bending air inlet to avoid direct radar wave illumination and reflection. We evaluate the efficacy of an S-shaped air inlet on RCS reduction by simulating the boresight and 15 bistatic RCS for a digital model of an engine located behind an S-shaped inlet, using a multi-level fast multipole method (MLFMM) code in the S and X bands. The results show that a curved S-type air inlet can reduce the engine boresight bistatic RCS by 10-12 dBsm at 3 GHz, and 16 dBsm at 10 GHz when radar wave is incident from boresight, but not to the level required by RF stealth standards. When the radar waves are incident from = 105 = 90 or = 90 = 345 , the RCS reduction is less effective, which is the results of the bend direction of the S-type air inlet.