A major portion of 'stealth design' is to deflect the radar signal in
directions away from the transmitter [i.e. deflect the echo]. Hence, the
many flat panels on the F-117.

A secondary feature of the design is absorbent material.

A third feature is the hex filter designs in the windows/turbine
aperture etc [allow rf in but keep it from getting out].

But, your basic absorbing material is found in numerous graphite epoxies
whose composition is classified.

You may find useful information on basics by checking out 'space cloth'.
Space cloth is used for radar dummy loads and is available in Zo that
provide VSWRs from 5:1 to 1:1. At 1:1 there is no reflection.

Frank Alforo wrote:

Anybody have any info the material used on the stealth aircraft to absorb
radar signals?