## 5 Finite Array Experimental Results
It can be seen that when scanning to 45\({}^{\circ}\), the simulated normalized cross-pol levels are around \(-\)86.5 dB in E- and H-planes. The simulated SLLs are \(-\)12.6 dB and \(-\)11.6 dB when scanning over all scan angles in E- and H-planes, respectively. At \(f_{0}\), the proposed PAA shows the ability to scan to \(\pm\)45\({}^{\circ}\) with gain fluctuations of 1.5 dB and 1.9 dB in E- and H-plane, respectively. It can be seen that when patterns are steered to 45\({}^{\circ}\), the simulated normalized cross-pol levels are less than \(-\)68 dB, both in E- and H-planes. The simulated SLLs are \(-\)12 dB and \(-\)11.7 dB in E- and H-plane, respectively. At \(f_{h}\), the proposed PAA exhibits a roll-off with 2 dB and 2.14 dB drops in E-plane and H-plane at \(\pm\)45\({}^{\circ}\). It can be seen that when scanning over all scan angles, the simulated normalized cross-pol levels are closed to \(-\)82.7 dB in E- and H-planes. The simulated SLLs are \(-\)12.3 dB and \(-\)11.6 dB when scanning over all scan angles in E- and H-planes, respectively. Remarkably, the measured results show that the proposed PAA can steer to \(\pm\)45\({}^{\circ}\) with impressive gain fluctuations of 2.2 dB and 2.9 dB in E-plane and H-plane, respectively. We note that the cross-polarization level is less than \(-\)68 dB during the scanning in the two principal planes. The SLL is less than \(-\)11.6 dB within the scanning range of \(\pm\)45\({}^{\circ}\) in the two main planes over the operation frequency band. Better SLLs can be acquired by employing the appropriate amplitude weighting. In general, the measured and simulated results agree well, including sidelobe levels and beamwidth, particularly in the main beam direction. It is noteworthy that the measured scanning gain fluctuation in the scan range of \(\pm\)45\({}^{\circ}\) surpasses the simulated one. This disparity can be attributed mainly to fabrication, soldering, and assembly tolerances. Table 2 shows the detailed simulated/measured scanning loss when scanning to \(\pm\)45\({}^{\circ}\). Figure 15: Normalized patterns at \(f_{h}\): (a) E-plane and (b) H-plane. Table 3 summarizes the performance of the proposed phased array. A comparison with other previous state-of-the-art phased arrays is also shown. In [15], the array is capable of 2D scanning with a roll-off with 3 dB, but the -pol level is relatively high in H-plane because it is a conventional array, even if it does not provide the X-pol level. Although the PAA in [16] exhibits a low gain fluctuation of 0.5 dB in E-plane, the scan range is only 15\({}^{\circ}\), and the X-pol level is only \(-14\) dB in H-plane. Though the PAA in [21] has a wide-angle scanning performance with low roll-off at 60\({}^{\circ}\) with small element space, the proposed design is able to have a low cross-polarization level in all planes rather than one plane. Moreover, it has a low gain fluctuation at 45\({}^{\circ}\) with 0.53\(\lambda_{0}\) element space. Thus, among the tabulated antennas outlined above, the proposed PAA has the most outstanding X-pol level, especially in H-plane. Furthermore, the proposed PAA exhibits a low gain fluctuation. Therefore, the proposed PAA has huge potential to be implemented in radar systems.