Infrared-Transparent, Millimeter-Wave Bandpass, Missile Dome Design

Agiltron will develop an infrared coating and Ka-band pass filter that can be used in missile domes and windows. An electrically conductive doped silicon thin layer is proposed as the shielding layer to replace the current embedded metal grid for shielding out-of-band microwave and radio frequencies. Silicon (Si) and aluminum oxide (Al2O3), both with good environment durability, are proposed for the high and low refractive index coating materials for the anti-reflection (AR) for the 3 to 5 micron band. This coating will protect the window and meet the environment survival requirements. All three coatings will be applied using the same technique, electron-beam evaporation. Agiltron’s approach to the Ka-band pass is a multi-cavity Fabry-Perot etalon utilizing the interface reflectance between high and low refractive index materials, Si and Al2O3. The Phase I program will develop two structures, one with the two filters physically separated but operating together, and the second with the two filters integrated into a single unit.