# Integration of Microstrip Slot Array Antenna with Dye-Sensitized Solar Cells
## 3 Results and Discussion  
The photograph of the 2 \(\times\) 2 circularly polarized microstrip slot array antenna integrated with the dye-sensitized solar cells is presented in Figure 4. It can be seen that the slot divides the entire antenna into nine parts, and each part is tightly connected to a dye-sensitized solar cell. Among them, three independent dye-sensitized solar cells are connected in series to improve the output voltage of the solar cells, and three series connected solar cells are connected in parallel to increase the output current of the solar cells. The dye-sensitized solar cell uses glass as the substrate, the cell and the antenna are grounded together by welding the negative electrode of the cell to the metal ground plant of the microstrip slot antenna. The high-illuminance xenon lamp is used as the light source to illuminate the microstrip slot array antenna integrated with dye-sensitized solar cells at a suitable distance. Figure 5a shows the related experiments on the energy output characteristics of the microstrip slot array antenna integrated  
Figure 4: Photograph of the 2 \(\times\) 2 circularly polarized microstrip slot array antenna integrated with dye-sensitized solar cells. Figure 3: (**a**) Reflection coefficient; (**b**) radiation efficiency of the microstrip slot with or without solar cell. with the dye-sensitized solar cells. The open-circuit voltage and short circuit current of dye-sensitized solar cells are 1.94 V and 99 mA, respectively, whether the antenna works or not. The dye-sensitized solar cells are externally connected with a sliding rheostat whose resistance varies from 0 to 100 \(\Omega\). The relationship between the output voltage and the output power of the solar cell under the two conditions of antenna operation and non-operation is measured by changing the value of the sliding rheostat, as shown in Figure 5b. It can be seen that the curves coincide basically when the antenna works or does not work, which indicates that, whether it works or not, the antenna has little effect on the performance of dye-sensitized solar cells. The \(2\times 2\) circularly polarized microstrip slot array antenna integrated with dye-sensitized solar cells is measured in an anechoic chamber to further validate its design; the illumination intensity was maintained at 150 W/m\({}^{2}\) and the relevant measurement environment is shown in Figure 6.  
Figure 5: (**a**) The related experiments on the energy output characteristics; (**b**) output power versus output voltage. Figure 7 shows the measured reflection coefficient and radiation pattern of the microstrip slot array antenna and the array antenna integrated with dye-sensitized solar cells. From the measurement results in Figure 7a, when the array antenna is integrated with dye-sensitized solar cells, the current generated when the solar cells work will have a certain influence on the reflection coefficient of the antenna, but the reflection coefficient performance of the array antenna integrated with dye-sensitized solar cells is still good on the whole. From the measurement results of Figure 7b, the gain of the microstrip slot array antenna is 6.48 dBi at 5.8 GHz, and the gain of the array antenna integrated with dye-sensitized solar cells is 0.12 dB higher than that of the microstrip slot array antenna, reaching 6.60 dBi. Generally, the existence of dye-sensitized solar cells has little effect on the gain performance of microstrip slot array antenna. Figure 8 shows the measurement results of the influence of the axial ratio parameters of the microstrip slot array antenna integrated with dye-sensitized solar cells. It can be found from Figure 8a that the axial ratio of the microstrip slot array antenna is 1.65 dB at 5.8 GHz; the axis ratio of the array antenna integrated with dye-sensitized solar cells is 1.50 dB. The existence of dye-sensitized solar cells has little effect on the circular polarization radiation performance of the microstrip slot array antenna.