Transverse probe antenna element embedded in a flared notch array

An antenna system comprising:

• an array of flared notch radiators, arranged in aligned rows to define a series of parallel troughs between adjacent flared notch radiator rows within an aperture area, said array polarized in a first sense aligned with said rows:
• absorptive RF loading material disposed in said troughs;
• and
• a transverse probe radiating element extending transversely through a plurality of said troughs to excite a series of parallel plate waveguide modes which are polarized orthogonally to the polarization sense of said array of flared notch radiators, and wherein said transverse probe element shares said aperture area.

An antenna system comprising:

• conductive means defining an array ground plane;
• an array of flared notch radiators extending generally orthogonally to said ground plane, arranged in aligned rows to define a series of parallel troughs between adjacent flared notch radiator rows within an array aperture area, said flared notch radiator array operating at a first frequency band:
• absorptive RF loading material disposed in said troughs adjacent said ground plane, said material having the characteristic of being absorptive of RF energy in said first frequency band and of appearing as a relatively low loss dielectric at a second frequency band, said second band lower in frequency than said first band;
• and
• means for exciting lower frequency radiation within or under said absorptive loading material, said means comprising a transverse probe radiating element extending transversely through a plurality of said troughs within or under said absorptive loading material, said transverse probe element sharing said aperture area.

A dual band airborne antenna system comprising:

• conductive means defining an array ground plane;
• an array of flared notch radiators extending generally orthogonally to said ground plane, arranged in aligned rows to define a series of parallel troughs between adjacent flared notch radiator rows within an array aperture area, said flared notch radiator array operating at a first frequency band:
• absorptive loading material disposed in said troughs adjacent said ground plane, said material having the characteristic of being absorptive of RF energy in said first frequency band and of appearing as a relatively low loss dielectric at a second frequency band, said second band lower in frequency than said first band;
• and
• Identify Friend or Foe (IFF) interrogation means, comprising an array of transverse probe radiating elements, each extending transversely through a plurality of said troughs within or under said absorptive loading material, said transverse probe array sharing said aperture area, and an IFF interrogator coupled to said transverse probe array through an IFF signal distribution network.