In this article, we present a tri-band multilayer antenna operating at 6 GHz, 8 GHz, and 28 GHz for short-haul point-to-point communication links. Using the shared aperture concept, we design two different low-frequency and highfrequency antennas and co-integrate them into a single multifunctional stack-up. The low frequency antenna employs aperture-coupled feeding in which dual resonance is achieved by adding a slot on the patch. The high-frequency antenna is also aperture coupled with a rectangular feeding slot and is placed on top of the lower-frequency antenna. The shared aperture antenna results in a compact design with dimensions of 0.58 λ × 0.48 λ × 0.039 λ, characterized by an extremely low vertical profile (λ = free space wavelength at the lowest frequency). Full-wave simulations demonstrate that the achieved bandwidths for the 6 GHz, 8 GHz, and 28 GHz bands are 1.3%, 0.58%, and 3.57 % with a broadside gain of 6.65 dBi, 7.87 dBi, and 7.73 dBi, respectively. The isolation is below -45 dB at the lower operating bands and -25 dB at the high band.
