# A Two-Port Dual-Band Dual-Circularly-Polarized Dielectric Resonator Antenna
## 2 Antenna Design and Analysis  
### Antenna Configuration  
The geometry of the proposed two-port DBDCP DRA is shown in Figure 1, with the corresponding optimized design parameters listed in Table 1. As illustrated in Figure 1a, the proposed DRA consists of a main DR, a cross-slot-coupled aperture etched on the ground plane, and two 50-\(\Omega\) microstrip feedlines printed on a dielectric substrate. The main DR is constructed with two stacked DR layers with different shapes, including a top hexagonal DR and a bottom cross-shaped DR, and is made of microwave ceramic material with a dielectric constant of 10.  
The hexagonal DR is formed by a square DR of dimension \(a_{1}\times a_{1}\times d_{1}\) with two opposite truncated corners of side length \(b\). The diagonal lengths of the crossed-shaped DR are different (\(a_{2}\
eq a_{3}\)) because tuning \(a_{3}\) appropriately enhances the AR bandwidths at both two operating bands. Two diagonal grooves having size of \(c_{2}\times h_{2}\) are etched on the cross-shaped DR for tuning the AR bandwidth of the LB. A longitudinal groove of size \(c_{1}\times h_{1}\) is engraved on the top of the hexagonal DR for tuning the AR bandwidth of the UB. The main DR is arranged diagonally relative to the \(x\)- and \(y\)-axes.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameter** & **Value** & **Parameter** & **Value** & **Parameter** & **Value** \\ \hline \(a_{1}\) & 22.71 & \(c_{3}\) & 7.07 & \(l_{8}\) & 4.7 \\ \(a_{2}\) & 26.46 & \(h_{1}\) & 6 & \(l_{81}\) & 12.4 \\ \(a_{3}\) & 32.11 & \(h_{2}\) & 8.9 & \(l_{82}\) & 22.3 \\ \(b\) & 15.06 & \(h_{3}\) & 3.41 & \(w_{81}\) & 3.2 \\ \(c_{1}\) & 2.26 & \(l_{71}\) & 12.49 & \(w_{82}\) & 1.3 \\ \(c_{2}\) & 2.25 & \(l_{72}\) & 8.45 & \(wf_{1}\) & 2.3 \\ \(d_{1}\) & 19.49 & \(l_{73}\) & 10.86 & \(wf_{2}\) & 0.65 \\ \(d_{2}\) & 4.41 & \(l_{74}\) & 7.31 & \(wf_{3}\) & 0.73 \\ \(d_{3}\) & 14 & \(l_{75}\) & 10.28 & \(l_{sub}\) & 0.762 \\ \(e_{1}\) & 4.24 & \(l_{6}\) & 7.33 & \(w_{sub}\) & 41 \\ \(e_{2}\) & 2.83 & \(l_{7}\) & 2.75 & & \\ \hline \multicolumn{5}{c}{Unit mm.} \\ \hline \end{tabular}
\end{table}
Table 1: Optimized parameters of the proposed two-port DBDCP DRA.  
Figure 1: Configuration of the proposed two-port DBDCP DRA. (**a**) Disassembled view, (**b**) upper view of the substrate, and (**c**) bottom view of the substrate.  
The dielectric substrate used here is a Taconic TLY-5 substrate (\(\varepsilon_{r}=2.2\) and tan\(\delta=0.0009\)) with a size of \(w_{sub}\times w_{sub}\) and a thickness of \(t_{sub}=0.762\) mm. The ground plane and the 50-\(\Omega\) microstrip feedlines are arranged on the top and bottom surfaces of the dielectric substrate, respectively, as displayed in Figure 1b,c. Two feedlines P1 and P2 are used to excite the main DR through the cross-slot-coupled aperture etching, which is constituted of a vertical slot and a horizontal slot etched on the ground plane. The 50-\(\Omega\) microstrip feedline P1 is bent into a \(\Gamma\)-shaped strip line and coupled through the vertical slot to excite the fundamental TE\({}_{111}\) mode of the main DR, whereas the 50-\(\Omega\) microstrip feedline P2 is connected to a fork-shaped strip line and coupled through the horizontal slot to excite the higher-order TE\({}_{113}\) mode of the main DR. Owing to the diagonal arrangement of the main DR, its two operating modes, the fundamental TE\({}_{111}\) and the higher-order TE\({}_{113}\) modes, split into two pairs of near-degenerate orthogonal modes of near-equal amplitudes and 90\({}^{\circ}\) phase difference. The proposed two-port DRA is optimized such that it yields RHCP radiation at the LB with excitation from the feedline P1, while it produces LHCP radiation at the UB with excitation from the feedline P2.