Compact integrated self-multiplexing antenna for sub-6 GHz and millimeter wave 5G frequency spectrum

This paper presents a compact integrated self-multiplexing antenna capable of operating across both the sub-6 GHz and millimeter-wave bands of the 5G frequency spectrum. The sub-6 GHz unit elements are alternately arranged with different structural dimensions to achieve eight distinct operating frequencies within the sub-6 GHz spectrum. Between each pair of sub-6 GHz unit elements, millimeter-wave unit elements of varying dimensions are incorporated to generate radiations at eight distinct frequencies in the millimeter-wave band. The first eight ports (P1–P8) operate at eight distinct frequencies of sub-6 GHz spectrum, whereas the remaining eight ports (P9–P16) are designed to radiate at eight distinct millimeter-wave frequencies. Electromagnetic waves in the sub-6 GHz spectrum are obtained by means of exciting TE110 mode in the modified eighth-mode substrate integrated waveguide (EMSIW) cavity resonators, while millimeter-wave radiation is achieved through the hybrid TE730 and TE750 modes of the EMSIW cavity resonators. The inter-port isolations better than 40 dB and 20 dB are obtained across the sub-6 GHz and millimeter-wave spectrum, respectively. This integrated placement of millimeter-wave elements efficiently utilizes the available substrate area while maintaining high inter-port isolation across the entire frequency spectrum. The design antenna system has an overall footprint of 0.425$$\:{\varvec{\lambda\:}}_{\varvec{g}}^{2}$$, where $$\:{\varvec{\lambda\:}}_{\varvec{g}}$$ corresponds to the guided wavelength at the lowest operating frequency. Owing to its compact dimensions, simple integrated design and excellent performance, the proposed self-multiplexing antenna emerges as a promising candidate for multiband communication systems operating in sub-6 GHz and millimeter-wave 5G spectrum.