Foldable Smartphone Antenna Design

The development of full-screen smartphones has led to the continuous expansion of screen-to-body ratios. However, this metric alone cannot fully represent the pinnacle of smartphone design evolution. The advent of foldable smartphones has ushered in a new era in the cellular phone industry, giving rise to a more diverse and complex landscape of antenna designs. The performance of these antennas has a significant impact on the communication quality of foldable phones. In this paper, the coupling of two antennas of a foldable smartphone is investigated. Specifically, the traditional inverted-F antennas (IFA) and loop antennas are designed, which operate in the N78 (3.3 GHz-3.8 GHz) frequency band of the 5G spectrum. The proposed loop antennas exhibit outstanding isolation performance when the foldable smartphone is in the folded state without the need for external decoupling measures.