This paper describes the design and testing of a prototype dual-band dual-p
olarized planar array operating at L- and X-bands, The primary objectives w
ere to develop new antenna technology with dual-band and dual-polarization
capability in a shared aperture, featuring low mass, high efficiency, and l
imited beam scanning. The design of a prototype planar microstrip array of
2 x 2 L-band elements interleaved with an array of 12 x 16 X-band elements
that meets these requirements is discussed in detail and measured results a
re presented. The array is modular in form and can easily be scaled to larg
er aperture sizes.