Patents Assigned to McDonnell Douglas Helicopter Corp.
  • Patent number: 5844518
    Abstract: The microwave absorption performance of a fiber loaded thermoplastic syntactic material is improved by geometrically reshaping the surface into a waffle shape. Starting with a fiber loaded version of thermoplastic syntactic foam, the front face geometry is then modified. Typically, the angle and frequency response is a function of both the front face angle and the skin thickness. These effects are minimized in this concept by using a pyramidal surface in which the field enters the material normal to at least one surface at almost all incident angles. The attenuation is over 20 dB, from S through Ku bands, over a broad angle range of up to 75 degrees off normal. An added benefit is that this system has a rigidity that is suitable for many structural applications.
    Type: Grant
    Filed: February 13, 1997
    Date of Patent: December 1, 1998
    Assignee: McDonnell Douglas Helicopter Corp.
    Inventors: Donald J. Berg, Carl A. Mentzer, David A. Brooker, Gregory J. Sapletal