# Passive Power Line Communication Filter Design and Benchmarking Using Scattering Parameters
## 5 PLC Filter Design, Simulation, and Evaluation
### Proposed Filter Evaluation and Comparison to Other Commercially Available Filters
#### 5.3.1 PLC Filter Insertion Loss and Power Consumption Measurements  
Insertion loss measurements were performed in the following conditions:  
* The test setup used is the PLC filter online insertion loss test setup 2 shown in Figure 7;  
Figure 16: PLC filters online insertion loss test setup version 2 measurements.  
Figure 17: Comparison between measured and simulated insertion loss.  
* The first step is to validate the test setup by directly connecting the PLC couplers to one another. The setup validity check is named \"PLC Couplers\" in the below figures;
* The subsequent actions involve conducting measurements while the filter is installed, considering three different states: no mains voltage named \"Unenergised\", mains voltage named \"Energised\", and a 2000 W load with the mains voltage named \"Energised with 2000 W load\". The naming convention utilized in the figures below, which display the results of insertion loss measurements, remains consistent.  
Figure 18 presents the insertion loss of the proposed filter.  
Figure 19 shows the schematic extracted from the datasheet of Filter 1. During measurements, the ground connection of the Y-capacitors between C2 and C3 was left floating and thus the filter was connected in the same way as an eighth-order passive filter or a two-stage filter from Figure 3b. Figure 20 presents the insertion loss of filter 1.  
Figure 19: Filter 1 schematic.  
Figure 20: Filter 1 insertion loss measurement using PLC filter online insertion loss test setup version 2.  
Figure 21 shows the reverse-engineered schematic of Filter 2 (the schematic was not available in the datasheet). The filter is a resonant type of filter with a resonance frequency between 20 kHz and 30 kHz, this is also visible in Figure 22 where the attention S21 [dB] has its minimum value. These types of filters have the disadvantage that the attenuation is highly dependent on the input and output resistance. Proof of this statement entails the huge difference in attenuation (10 dB to 40 dB) from Figure 22 between the attenuation when the filter is energized (no load) and the case when the filter has a 2000 W load. Figure 22 presents the insertion loss of filter 2.  
Figure 23 shows the schematic extracted from the datasheet of Filter 3 which is a sixth order passive filter. Figure 24 presents the insertion loss of filter 3.  
Figure 21: Filter 2 schematic.  
Figure 22: Filter 2 insertion loss measurement using PLC filter online insertion loss test setup version 2.  
Table 2 summarizes the results of the insertion loss measurements and power consumption measurements while comparing them to datasheet values. The rated current value is written in the table as a similarity reference between the filters.  
The data from Table 2 are obtained from below methods and sources:  
* Power consumption measurements at 230 V 50 Hz;
* Insertion loss extracted from measurement results is shown in Figures 18, 20, 22 and 24;
* Insertion loss gap measurement using PLC signal filtering capability test setup version 1 is shown in Figure 11. These measurements reflect the gap between the filter attenuation and the attenuation at which the communication stops.  
The filter developed in this study exhibits exceptional features, including the best insertion loss versus frequency, a three-fold increase in attenuation at 50 kHz (\(-\)130 dB) in comparison to the best commercially available filter (\(-\)40 dB), and a power consumption of 0.6 W, similarly to the most power-efficient commercial filter (0.5 W). Furthermore, it has the second-best input and output impedance of 3.6 \(\Omega\) within the frequency range of 35-95 kHz.