Design of thick frequency selective surfaces with complex apertures: Dichroics with cross-shaped and stepped rectangular apertures

Recent work has shown the successful demonstration of design techniques for straight, rectangular apertures at an incident angle of 30 degrees . In the present work, some of the cases in which the straight rectangular shape may have limited usefulness are addressed. For example, grating lobes become a consideration when the bandwidth required to include the new frequency of 7.165 GHz conflicts with the desired incident angle of 30 degrees . For this case, the cross shape's increased packing density and bandwidth could make it desirable. When a sharp frequency response is required to separate two closely spaced Ka-band frequencies, the stepped rectangular aperture might be advantageous. >