Extremely Low-Profile Dual-Band Antenna Based on Single-Layer Square Microstrip Patch for 5G Mobile Application

This letter presents an extremely low-profile dual-band antenna based on a single-layer square microstrip patch for 5G mobile application. The antenna has a height of only 0.8 mm (about 0.009
λ_L
at 3.45 GHz) and a footprint of 30 × 30 mm
²
(0.345 × 0.345
λ_L
²
). The TM
₁₀
mode at around 3.56 GHz and the TM
₁₁
mode at around 4.91 GHz for the antenna are obtained by etching a pair of symmetrical circular notches and a narrow rectangular slot on the square patch. The TM
_1/2,0
mode at around 3.45 GHz and the TM
_1/2,1
mode at around 4.83 GHz of the antenna are generated by further placing two two-order matrix-style shorting pins. The combination of the four modes can overcome the effect of insufficient bandwidth due to the very low profile, resulting in 3.4–3.6 GHz (partial 5G N78 band) and 4.79–4.94 GHz (partial 5G N79 band) dual-band operation. The measured results are also presented.