Grating Lobes Reduction Using a Multilayer Frequency Selective Surface on a Dual-Polarized Aperture Array Antenna in Ka-Band

This paper presents a multilayer frequency selective surface for a dual-polarized aperture array antenna in Ka-band. The 8 × 8 elements of the array are cylindrical open cavities with a diameter of 0.6λ₀ at 30 GHz, and spaced one wavelength. Due to this separation between elements, which is limiting and not reducible by the architecture of the feeding network and the size of the radiating element, grating lobes appear. Frequency Selective Surfaces (FSS) can be a solution to this problem without modifying the feeder architecture nor the radiating elements. This paper presents the FSS design for reducing grating lobes level, the antenna assembly, and the experimental validation. The full antenna performance demonstrates that FSS operates in a range identical to the feeder (29.5 GHz to 31 GHz) with the added benefit of reducing the grating lobes level more than 10 dB for both polarizations.