An apparatus may include one or more conductive surfaces, waveguide structures and/or ports. One or more waveguide structures may include a portion disposed above a conductive surface, an outer conductor, and/or an inner conductor. A first portion of an outer conductor may be connected to a conductive surface. A port end of an outer conductor may be connected to an outer conductor port. An inner conductor may be disposed inside and spaced apart from an outer conductor. An inner conductor port may be connected to an inner conductor. An inner conductor of two or more waveguide structures may be connected to each other. A conductive surface may include at least one aperture portion, which may have a width substantially similar to the width of a waveguide structure. A substrate may be disposed between one or more waveguide structures and a conductive surface for a substantial portion of a waveguide structure.