# A Low-Profile Dual-Polarized Magneto-Electric Dipole Antenna for 5G Applications
## 2 Materials and Methods
### Dual-Polarized Structure  
Compared with single-polarized antennas, dual-polarized antennas can realize duplex transmission and reception, and also expand communication capacity, which means greater advantages in the field of communication. At the same time, the dual-polarized antenna  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**lg** & **le** & **ls1** & **ls2** & **lm** & **hm** & **hs** \\ \hline
90 & 24 & 6 & 6 & 12 & 13 & 1 \\ \hline
**h1** & **w1** & **w2** & **hd** & **hfl1** & **hf2** & **lf1** \\ \hline
3 & 6 & 8 & 2 & 10 & 9.5 & 20 \\ \hline
**lf2** & **d** & & & & & \\ \hline
10 & 4 & & & & & \\ \end{tabular}
\end{table}
Table 1: The specific dimensions of the antenna (units: mm).  
has stronger anti-interference ability, which can effectively resist multipath fading and improve the sensitivity of the system. In the design of dual-polarized antennas, the design of the feed structure counts a great deal.  
Figure 1: Antenna geometry: (**a**) configuration of the proposed MED; (**b**) top view of the proposed MED; (**c**) configuration of the proposed MED’s magnetic dipoles; (**d**) configuration of the proposed MED’s feeding structures.  
Some researchers use slot coupling feeds in antenna design [19; 20], in order to realize higher isolation between different ports. However, it also results in a higher processing cost and structural complexity. \(\Gamma\)-type feeding structures with simple structures and low processing costs can realize impedance matching in a wide frequency band; hence, \(\Gamma\)-type feeding structures were adopted in the proposed antenna. Figure 1d shows the \(\Gamma\)-type feeding structures consisting of three parts. The first part is the vertical part whose bottom is connected with the coaxial core under the metal ground. The second part, i.e., the horizontal part of the \(\Gamma\)-shaped feeding structures, which is inductive, transmits energy to the horizontal electric dipole and the vertical magnetic dipole by coupling. The vertical part on the other side is the third part of the \(\Gamma\)-shaped feeding structures, which is capacitive. By optimizing the length of the third part, the capacitive part and the inductive part of the second part can cancel each other out. The horizontal part of one feeding structure was bent to improve the isolation of two ports.  
Figure 2 depicts the current distributions on the electric dipoles when the two ports are excited separately, and T is one operational period. The current on the electric dipoles reached the maximum intensity at time 0; see Figure 2a,c, which indicate that the horizontal metal patches were strongly excited. Meanwhile, at time T/4, the currents on the horizontal metal patches attained minimum intensity, but the currents on the radiating slot between the patches reached the maximum, as shown in Figure 2b,d. This means that the magnetic dipole was strongly excited. In summary, the electric dipole and the magnetic dipole were alternately excited, in line with the operating characteristics of the MED. The above results show that the two ports excited similar intensity on the MED. Therefore, the feeding structures could be used to excite the dual-polarized MED.  
Figure 2: Simulated current distributions on the electric dipoles: (a) port1 at time = 0; (b) port1 at time = T/4; (c) port2 at time = 0; (d) port2 at time = T/4.