## 3 Experimental Results  
After the design is completed, each functional block is integrated onto the circuit board in a multi-layered manner for verification and measurement. The multi-layer board is divided into three pieces for fabrication. These individual boards are then pressed together and combined using a coupling method. The finished product after splitting the multi-layer board into three pieces is shown in Figure 11, representing the bottom layer; Figure 11a shows the filter circuit; the middle layer with the Rotman lens is shown in Figure 11b; and top layer with the array antenna is shown in Figure 11c. The measurement environment setup is illustrated in Figure 12, with the outdoor and indoor spaces simulated by a glass panel. A network analyzer (Keysight (Santa Rosa, CA, USA) N5227A 2-Port PNA Network Analyzer) is used, with Port 1 connected to the transmitting standard antenna array set up outdoors and Port 2 connected to the receiving standard antenna array set up indoors. During measurements, the angle of the receiving antenna on the indoor side remains constant (0\({}^{\circ}\)), while the transmitting antenna on the outdoor side emits signals toward the STP and glass at three different angles, 0 \({}^{\circ}\), +24 \({}^{\circ}\) and \(-24\)\({}^{\circ}\), as shown in Figure 13. Two sets of data are compared between without activating the STP, and with the STP being activated. The measured data for both cases are as follows, primarily observing changes in the penetration coefficient to understand whether the STP functions as expected. According to the simulation results of the integration of the Rotman lens and array antenna in Section 3, the gain of the array antenna is approximately 10 dB. Each set of STPs has an ideal gain of 20 dB, with an approximately 3 dB loss deducted from the simulation results of the filter coupler in Section 2. It is expected that the planer's operational condition can improve the gain by approximately 17 dB compared to the non-operational condition. Figure 11: Geometry of the smart transfer planer. (**a**) Bottom layer. (**b**) Middle layer. (**c**) Top layer. Figure 12: (**a**) Schematics of the mutual positions of the STP, receiving (Rx) and transmitting (Tx) horn antennas in the spherical coordinates system. (**b**) Experimental setup for measuring the S-parameter. Comprehensive simulation results show that for angle \(-24^{\circ}\), the double-planer gain is 18.98 dB, with an expected gain of approximately 15.98 dB after subtracting the filter coupler loss. For angle \(0^{\circ}\), the double-planer gain is 20.3 dB, with an expected gain of approximately 17.3 dB after subtracting the filter coupler loss. For angle \(+24^{\circ}\), the double-planer gain is 19.94 dB, with an expected gain of approximately 16.94 dB after subtracting the filter coupler loss. Without activating the STP, the angle of the receiving antenna on the indoor side remains constant (\(0^{\circ}\)), and the transmitting antenna on the outdoor side emits signals towards the STP and glass at three angles (\(-24^{\circ}\), \(0^{\circ}\) and \(+24^{\circ}\)). By observing the S-parameters through the network analyzer, it can be seen that after spatial loss, the penetration coefficient at the operating frequency of 12.5 GHz is \(-52.2\) dB for the \(-24^{\circ}\) angle, \(-53.9\) dB for the \(0^{\circ}\) angle, and \(-50.6\) dB for the \(+24^{\circ}\) angle, as shown in Figure 13a-c, respectively. With the STP activated, the angle of the receiving antenna on the indoor side remains constant (\(0^{\circ}\)), and the transmitting antenna on the outdoor side emits signals toward the STP and glass at three angles (\(-24^{\circ}\), \(0^{\circ}\), and \(+24^{\circ}\)).