## 3 Materials and Methods
### Measurement Campaign  
The experimental frequency scan measurements were conducted in two densely populated urban cities in the Kogi and Lagos States in Nigeria. The densely populated cities are located in different geo-political zones, in the south-west and north-central regions, respectively [49, 50]. These areas have been chosen due to the location of the microwave links and ease of access. Additionally, such environments have recently been described as fast-growing urban cities [51]. The need to test the performance of the microwave links in such cities to know the impact of RF1 on the links has become imperative. A graphical representation of the geographical coordinates of the measurement environments is given in Figure 2.  
The measurements equipment deployed to the microwave link locations in these cities comprised a spectrum analyzer-Anritsu model MS2724C [52] and a 0.6 m antenna dish [3]. The spectrum analyzer ranged from 9 kHz to 20 GHz. The broadband preamplifiers over the whole frequency range for increased sensitivity was approximately 17 dB. A hardware description of the experimental setup for the frequency scan measurements is as shown in Figure 3. Here, the fixed base transceiver station, the spectrum analyzer, and the 0.6 m antenna are depicted. The frequency bands that were tested included the 6 GHz, 7 GHz, and 8 GHz bands. The frequency usage plan for the various frequency bands that were investigated is given in Table 3. The measurements covered the full azimuth and the vertical and horizontal polarizations for all scenarios. The spectrum master was chosen due to its design capabilities, making it suitable for RF testing and microwave link troubleshooting. Additionally, the analyzer can detect spurious signals and radio frequency interference in the microwave radio links. Furthermore, it is very flexible and relatively easy to operate with minimal difficulty.  
Figure 2: The geographical coordinates of the measurement environments.  
In order to start the frequency scan measurements, we made two selections to set the frequency range of the analyzer. The frequency knobs were adjusted appropriately to start and stop, and these settings were utilized for the sweeping exercise. In addition, we scanned the desired frequency span from the lowest to the highest frequency band in the tested frequency range. Additionally, we set the speed of the scan on the spectrum master to scan the frequency range for a faster measurement completion time. Furthermore, we adjusted the scanning mode feature on the analyzer to display the signal strength or amplitude. This feature was used to monitor the amplitude variations and frequency in the uplink on the analyzer. The output gives valuable information on the most suitable frequency and severe interference in the scanned frequencies. The in-phase and quadrature (1/Q) data were also derived using the time/amplitude and frequency details obtained from the baseband processing by sliding a spectrum window across the tested frequency spectrum as an amplitude function. Additionally, the analyzer was connected to the fixed antenna and was allowed to sweep for a day. In this case, the scan measurements were saved to the analyzer at an hour interval, and the scans were then extracted to a personal computer for further processing. Finally, the frequency scan measurements were analyzed in MATLAB, and the results are presented in Section 4 of this paper.