# A Patch/Dipole Hybrid-Mode Antenna for Sub-6 GHz Communication
## 2 Antenna Design and Analysis  
Figure 1 presents the geometry of the proposed antenna, which consists of an elliptical slotted patch, a feeding dipole connected with a broadband balun, and top and bottom substrates. The elliptical slotted patch is printed on the top side of the top substrate, which has been demonstrated to operate in an ultra-wideband for unidirectional radiation due to its tapered structure [11]. To ease the assembly and soldering, the feeding dipole is split into two parts on the top and bottom sides of the top substrate and these two parts are connected by the plating through holes. Two vertical parallel feeding lines, i.e., the balun structure, are designed to differentially excite the feeding dipole. The impedance transformation is implemented by a tapered line and printed on the top side of the bottom substrate. The ground plane is printed on the bottom side of the bottom substrate. All substrates used are FR4 materials. Four parameters are used to describe the geometry of the slotted patch, namely, the halves of the long axis and short axis of the elliptical slot (\(L_{S}\), \(W_{S}\)), and those of the elliptical patch (\(L_{P}\), \(W_{P}\)). The elliptical patch is tuned to operate at its fundamental mode in the lower frequency band at its initial design. With an elliptical slot etched on its center, each arm of the feeding dipole has a length of about a quarter of the wavelength [8]. By properly selecting the value, the hybrid mode can be sequentially excited in the band of interest. The detailed dimensions of the proposed antenna are listed  
Figure 1: Geometry of the proposed antenna (**a**) side view, (**b**) perspective view, and (**c**) zoom in (part A: the feeding dipole, part B: the tapered line, and part C: both sides of the balun). in Table 1. The sizes of the top and bottom substrates are 100 mm \(\times\) 100 mm and 130 mm \(\times\) 130 mm, respectively. The profile of the antenna is 10 mm. For better understanding the operation of the proposed antenna, the electric field distribution underneath the radiator is extracted and displayed in Figure 2. The feeding network and balun are removed for more distinct modes and the antenna is excited at the center of the feeding dipole. The port is excited with an identical unit input power throughout all frequencies. The same scale is shared on the left. It is found that the dipole plays an important role in the higher frequency region. The patch mode dominates the radiation over the operating frequency range. Additionally, the slotting technique in the center of the patch can help to suppress the cross-polarization level [12]. Figure 3 shows the simulated radiation patterns without the feeding network and balun. In the operating frequency band of 3.0 to 5.0 GHz, both _xoz_ and _yoz_ planes can maintain stable radiation patterns in terms of half-power beam-widths (HPBWs). More to the point, the HPBWs are 68.40\({}^{\circ}\), 67.98\({}^{\circ}\), and 58.36\({}^{\circ}\) in the _xoz_ plane and 56.02\({}^{\circ}\), 57.46\({}^{\circ}\), and 41.62\({}^{\circ}\) in the _yoz_ plane at 3.0, 4.0, and 5.0 GHz, respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline
**Parameter** & \(L_{1}\) & \(L_{2}\) & \(L_{3}\) & \(L_{4}\) & \(L_{5}\) & \(L_{6}\) & \(L_{7}\) & \(L_{8}\) & \(L_{9}\) & \(L_{10}\) & \(L_{11}\) & \(L_{12}\) & \(h_{1}\) & \(h_{2}\) \\ \hline
**Value (mm)** & 100.00 & 130.00 & 1.20 & 5.20 & 5.20 & 5.80 & 29.40 & 35.00 & 1.60 & 6.80 & 3.20 & 11.40 & 1.60 & 1.60 \\ \hline
**Parameter** & \(W_{1}\) & \(W_{2}\) & \(W_{3}\) & \(W_{4}\) & \(W_{5}\) & \(W_{6}\) & \(W_{7}\) & \(W_{8}\) & \(W_{9}\) & \(L_{5}\) & \(W_{5}\) & \(L_{P}\) & \(W_{P}\) & \(H\) \\ \hline
**Value (mm)** & 100.00 & 130.00 & 3.20 & 0.50 & 2.92 & 8.00 & 3.00 & 0.50 & 0.42 & 30.75 & 8.35 & 33.75 & 29.25 & 10.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Dimensions of the Proposed Antenna.