# Millimeter Wave Attenuation Due to Wind and Heavy Rain in a Tropical Region
## 2 Experimental Setup  
Figure 1 shows the experimental setup of the mm-wave FWS in Thailand. The poles in the setup were made using stainless steel (SS400) with a diameter of 101.6 mm (4 inches) and a thickness of 3.2 mm. The height (\(h_{1}\)) of an antenna of site 1 was 3.5 m; the total pole length was 4.0 m. Two accelerometers were attached to the pole at heights of 1.5 m and 3.0 m from the base. A weather logger for collecting wind, temperature and rain information was set on the top of the pole. The height (\(h_{2}\)) of the antenna of site 2 was 1.5 m; the total pole length was 2 m with lateral clamps. Thus, the pole deflection at site 2 should be negligible. The distance between the two sites was \(r_{0}=150\) m.  
The map of the experimental area is shown in Figure 2. The locations of the antennas (GPS coordinates 18.796271\({}^{\circ}\) N, 98.9813423\({}^{\circ}\) E and 18.7959594\({}^{\circ}\) N, 98.9520609\({}^{\circ}\) E) were on the roofs of the two tallest buildings (4 stories). There was a line of sight (LOS) between the two antennas. We have analyzed in the supplementary materials, Figure S4 and Table S1, that the primary Fresnel zone was well clear of any obstruction, thus multipath interference may be ignored.  
Figure 1: The experimental setup of the mm-wave FWS with antennas and poles. The accelerometers and weather sensor were installed at Site 1 where the pole vibration can be measured.  
Figure 2: The map of experimental locations with their GPS coordinates.  
The equipment and their connections are also shown in Figure 3. Acceleration information obtained via the accelerometers, which has three-axis sensitivity, was captured via a data logger. The received signal strength indicator (RSSI) of the FWS main unit was also stored in the data logger in every 10 ms. The data logger was controlled via a single board computer such as Raspberry Pi. The weather data sensed by the weather logger were directly captured by the computer in every 10 s. In the other site, only the RSSI information was acquired via another single board computer, which controlled the FWS unit. All the data were transported via the Ethernet network to a data server.  
The followings are the specifications of the equipment. The FWS unit is NEC iPASOLINK EX Advanced, with a minimum Tx power of \(-5\) dBm and frequencies of 71-76 GHz and 81-86 GHz. The carrier frequency \(f=74.625\) GHz of the link from site 2 to site 1 was selected in the experiment. Automatic gain control (AGC) was turned off so that real-time attenuation due to weather effects could be measured. The antennas are COMMSCOPE-VHLPI-80 with a diameter of 0.3 m, beamwidth of 0.9\({}^{\circ}\), 43.5 dBi gain, 14.0 dB return loss and a Voltage Standing Wave Ratio (VSWR) of 1.50. The total weight of each antenna and its mounting bracket is 7 kg. The pair of accelerometers (IMV-VP-8013M) measured 3-axis accelerations with a sensitivity of 44.9 mV/(m/s\({}^{2}\)). Their responses are in a range of 0.04-1000 Hz. The maximum measurable acceleration is \(\pm 58.8\) m/s\({}^{2}\). The RSSI level from the FWS unit and accelerometer data were sampled via the data logger (GRAPHITEC-GL980 midi LOGGER) at 10 ms intervals. Each data logger input has a 16-bit ADC with 0-30 V input range and 0-200 kHz frequency response.  
The weather sensor (VAISALA-WYCT536), located at site 1, can measure barometric pressure, air temperature, relative humidity, precipitation, and wind. The precipitation sensor has a collection area of 60 cm\({}^{2}\) and can measure the rain rate in a range of 0-200 mm/h. Each value of the rain rate is a running 1-min average in 10-s intervals. The wind sensor can measure the wind speed in the range 0-60 m/s at a resolution of 0.1 m/s, with a response time of 0.25 s. Wind direction information can also be gathered with \(\pm 3^{\circ}\) accuracy at 10 m/s. The weather sensor data were sampled at 10-s intervals using a Raspberry Pi.