![]() It can be seen that the filters conventionally mounted exhibit a drop in attenuation at higher frequencies. The following insertion loss curves based on actual measurements, show the effect. This greatly improves the screening between filter input and output, thereby enhancing the high frequency response. Whilst SBSG, SBSM and SBSP filters can be mounted conventionally on PCBs, they are also suitable for mounting in a wall or partition on a board. Solder connections made to each end (signal lines) and each side band (earth track). ‘C’ and ‘Pi’ filters are mounted to PCBs and soldered in identical manner to chip capacitors. ![]() Effects of mounting method on Insertion Loss It is therefore important to test the filters in circuit to determine the performance level achieved. The effect of the board makes it difficult to directly compare parts unless the mounting details are defined. All measurements are taken using a Vector Network Analyser in a 50Ω system, no load. It is important to recognise that the board material, thickness and layout, the plating finish, the grounding efficiency and the circuit impedances will all have an effect on the actual performance of the filter in operation. The boards are mounted to brass support jigs for mechanical stability and electrical grounding. Solder pads are ‘T’ bar with respect to the track and dimensionally match the recommendations given. Insertion loss plots and figures supplied are typical only and are measured on 50Ω stripline open boards, 0.8mm thick FR4 with gold plated tracks.
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