A Tri-Polarized Antenna With Diverse Radiation Characteristics for 5G and V2X Communications

A tri-polarized antenna with diverse radiation characteristics is proposed in this paper. This design mainly consists of two pairs of loop radiating dipoles and an omnidirectional monopole antenna element, which are used for the fifth generation (5G) and vehicle to everything (V2X) communications, respectively. By adding eight pairs of inverted L-shaped patches with unequal sizes around the proposed dipoles, wide beamwidths in both E- and H-planes can be obtained across the desired lower and upper frequency bands. Furthermore, by employing eight fork-shaped microstrip stubs to combine the circular monopole antenna element and the L-shaped patches, the flare angle of the conical beam can be increased to 180<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula>, which results in gain enhancement in the azimuth plane. Finally, the proposed loop radiating dipoles are excited by a pair of symmetrical differentially-fed feeding lines. Consequently, high port isolation for the proposed loop radiating dipoles as well as low gain variations for the monopole antenna element can be achieved. Measured results show that the impedance bandwidths of 32.84<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (2.8–3.9 GHz) and 18.18<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (4.5–5.4 GHz) can be achieved for the 5G communications. Wide half power beamwidths (HPBW) of larger than 103<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> in E-plane and 91<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> in H-plane can be achieved across the operating bands. In addition, a bandwidth of 5.5<inline-formula><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (5.82–6.15 GHz) with gain of 2.47 <inline-formula><tex-math notation="LaTeX">$\pm$</tex-math></inline-formula> 0.69 dBi in the azimuth plane can also be obtained for V2X communications.