# Multi-Band Unmanned Aerial Vehicle Antenna for Integrated 5G and GNSS Connectivity
## 2 Dual-Port Inverted T-Shaped MIMO Antenna and Analysis  
A dual-port inverted T-shaped multi-port antenna was designed with a defective ground. Initially, the T-shaped patch was designed with slots to achieve the dual bands of the 5G and GNSS frequencies. To tune the frequency and achieve circular polarization, the L-shaped stub with a defective ground structure was introduced. The schematics of a single-patch antenna, a multi-port antenna, and a multi-port antenna with an FSS are depicted in Figure 2, respectively. The single-patch antenna is fed through a micro-strip feedline. The feedline is connected to an inverted T-shaped patch with a slot introduced in the center. The inverted T-shaped patch is printed on a Schott Foturan II (Ceramized at 560 degrees) with \(\varepsilon_{r}=5.8\), and the frame ground is fabricated on the bottom of the substrate with appropriate slots on the ground. Here, H refers to the substrate thickness, and G denotes the length and width of the substrate. The resultant values for each parameter are listed below in Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameters** & **Value (mm)** & **Parameters** & **Value (mm)** \\ \hline Width (G) & 80 & W5 & 13 \\ \hline Length (G) & 80 & L5 & 14.5 \\ \hline H & 4 & W6 & 16 \\ \hline W1 & 11 & L6 & 35.5 \\ \hline L1 & 13 & W7 & 3 \\ \hline W2 & 14 & L7 & 10 \\ \hline L2 & 11 & W8 & 31 \\ \hline W3 & 28 & L8 & 11 \\ \hline L3 & 32 & W9 & 13 \\ \hline W4 & 49.5 & W10 & 8.5 \\ \hline L4 & 14.5 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Dimensions of the proposed single-patch antenna. Figure 1: Development of a dual-port MIMO antenna on a drone for 5G and GNSS connectivity. This dual-band single-patch element was studied for the GNSS E6 band with circular polarization and the 5G n79 band with linear polarization. Figure 3 represents the S11 parameter of a single-patch antenna, a MIMO antenna, and a MIMO antenna with an FSS. The structure attains the required reflection coefficient value of less than \(-10\) dB for both bands. Further, the MIMO antenna with a \(1\times 2\) configuration evolved from the single-patch antenna, as shown in Figure 4, to increase gain and directivity. Both antenna elements are oriented at 90 degrees to each other. The dual-port elements are positioned in a space of \(\lambda=60\) mm. The main application of this antenna is in vehicular networks. The required S11 value of less than \(-10\) dB was also achieved for the MIMO antenna. The single-patch radiating antenna was constructed in the form of an inverted T-shaped patch with a defective ground layer to achieve dual-band frequency operation. The ABCD matrix is defined for a 2-port network in terms of the total current and voltage. The equation is as follows:  
\[ \begin{bmatrix}V_{1}\\ I_{1}\end{bmatrix} = \begin{bmatrix}A&B\\ C&D\end{bmatrix}\begin{bmatrix}V_{2}\\ I_{2}\end{bmatrix}  \tag{1}\]  
Figure 2: Geometry and parameters of (**a**) the slotted ground, (**b**) slotted patch, and (**c**) anterior view of the single-patch element. The mathematical analysis of ABCD parameters is carried out by using the total transfer matrix, which includes a transmission line, an open circuit, and a defective microstrip structure. The overall reflection coefficient (S\({}_{11}\)) was analyzed by using ABCD parameter  
Figure 4: (**a**) Slotted grounds, (**b**) anterior view of the proposed \(1\times 2\) MIMO antenna. Figure 3: S-parameter of the single-patch antenna, the MIMO antenna, and the MIMO + FSS antenna. matrices. The GNSS band of S\({}_{11}\) was derived using a lossy transmission line (T\({}_{A1}\)), the electrical length (\(\theta\)), and the characteristic impedance (\(Z_{0}\)) of the ABCD matrix:  
\[T_{A1}= \begin{bmatrix}A&B\\ C&D\end{bmatrix} = \begin{bmatrix}\cos\theta&jZ_{imp}\sin\theta\\ j\sin\frac{\theta}{Z_{imp}}&\cos\theta\end{bmatrix} = \begin{bmatrix}0.847&j26.5 \\ j0.0106&0.847\end{bmatrix}  \tag{2}\]  
The ABCD matrix for the open circuit (T\({}_{B}\)) is as follows:  
\[T_{B1}= \begin{bmatrix}A&B\\ C&D\end{bmatrix} =