A frequency diverse phased-array antenna operates simultaneously in two bands. A checkerboard of antenna elements for a first wavelength is offset with a second checkerboard of second antenna elements. Within the substrate is a three dimensional checkerboard of ground planes and ground walls which provide signal isolation between the bands. Multiple ground planes optimize operation at the several frequencies. Phased-array elements are isolated by a conductive wall in a multi-layer substrate. Orthogonal polarization of antenna patches further improve signal discrimination. Below the surface layer, another conductive wall isolates each quadrature hybrid. The conductive wall can be realized by metal vias or metal mesh infused through a dielectric and surrounding a raised ground plane to isolate electrical fields at each frequency. A conductive wall also provides quadrature hybrid isolation.