An Ultralow-Profile Dual-Wideband Antenna Based on Multiple Modes and Multiple Coupling for 5G Terminal Application

An ultralow-profile dual-band antenna based on half-mode substrate integrated waveguide (HMSIW) and shorted patches for 5G mobile terminal applications is proposed in this letter. The antenna has a height of only 0.5 mm (0.006λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub>) and occupies a footprint of 38.5 mm × 40 mm (0.43λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> × 0.45λ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub>). First, three modes are obtained by exciting the HMSIW antenna loaded with cross slots, specifically the TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> mode at 3.5 GHz and the even/odd TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub> modes around 4.9 GHz, enabling dual-band operation. Next, by parasitizing two shorted patches on the left side and one on the bottom of the HMSIW, two modes at 3.5 GHz and one mode at 4.9 GHz are introduced. Based on this structure, three operating modes can be obtained respectively at 3.5 GHz and 4.9 GHz band, effectively overcoming the bandwidth limitations caused by the extremely low profile. Measured results show that the bandwidth of the antenna can cover partial N78 band from 3.4 GHz to 3.6 GHz and partial N79 band from 4.7 GHz to 5 GHz. The average efficiencies are −2.45 dB in the N78 band and −2.94 dB in the N79 band. This design provides a promising solution for ultralow-profile dual-wideband mobile terminal antennas.