## 5 Results  
In this study, we proposed and investigated a Frequency Selective Surface (FSS) with harmonic suppression and wide-angle beam steering characteristics. The FSS design integrated a grid structure for band-pass filter characteristics and a loop structure for band-stop filter characteristics, both implemented on a dielectric substrate. The proposed FSS aimed to suppress unwanted harmonics while maintaining efficient signal transmission at the desired operational frequencies. Extensive parameter sweep studies were conducted to understand the influence of various design parameters on the performance of the FSS. It was observed that increasing  
Figure 16: Comparison of the simulated and measured results during beam steering @3.0 GHz: (**a**) azimuth, (**b**) elevation. Figure 14: Comparison of the simulated and measured results: (**a**) radiation pattern @3.0 GHz, (**b**) maximum gain. Figure 15: Comparison of the simulated and measured results: (**a**) radiation pattern @6.0 GHz, (**b**) maximum gain. the width between patches (\(w_{1}\)) led to a higher resonant frequency of the operating band due to the reduction in grid capacitance (\(C_{\mathit{grid}}\)). Similarly, increasing the inductance (L) resulted in a higher resonant frequency, attributed to a decrease in grid inductance (\(L_{\mathit{grid}}\)). In the harmonic band, increasing the loop thickness (\(w_{5}\)) caused the harmonic resonant frequency to shift to a lower frequency, which was due to an increase in loop inductance (\(L_{\mathit{loop}}\)). These findings were critical in fine-tuning the FSS design for optimal performance. Regarding the substrate parameters, increasing the dielectric constant shifted the overall resonant frequency to a lower range, whereas decreasing the dielectric constant caused a shift to a higher frequency. Additionally, increasing the substrate thickness resulted in a higher overall resonant frequency, while reducing the thickness shifted the resonance to a lower frequency. These substrate effects were carefully considered to minimize transmission loss and achieve the desired filtering characteristics. To validate the performance of the proposed FSS, a series of measurements were conducted using a 4 \(\times\) 4 array patch antenna operating at 3.0 GHz. The FSS was positioned above the array antenna, and measurements were taken in an anechoic near-field chamber. The results demonstrated that the FSS operated correctly as a band-pass filter at 3.0 GHz, with minimal transmission loss and effective suppression of harmonics at 6.0 GHz. Repeated and comparative experiments were performed to ensure the reliability and consistency of the experimental results. Multiple measurements under identical conditions confirmed the reproducibility of the data, and comparative experiments validated the performance of the antenna system with and without the FSS. The experimental findings were cross-verified with theoretical models and simulations, which further confirmed the accuracy and credibility of the results. The measured radiation patterns and maximum gain values indicated that the FSS maintained efficient signal transmission while effectively suppressing harmonics. The 2D radiation pattern and maximum gain were measured during steering in the boresight, azimuth (30\({}^{\circ}\)), and elevation (30\({}^{\circ}\)) directions. At 3.0 GHz, the maximum gain in boresight was 17.25 dB without the FSS and 17.12 dB with the FSS. At 6.0 GHz, the maximum gain was 12.79 dB without the FSS and 2.69 dB with the FSS, demonstrating harmonic suppression of 10.1 dB. Furthermore, the proposed FSS exhibited wide-angle beam steering capabilities, validated through electronic beam steering experiments. The phase adjustments for beam steering were achieved by modifying the length of the coaxial cables, and the results showed consistent performance across different steering angles.