Hi. I need to connect an antenna to a BPF (Band Pass Filter) and this one to a transceiver. The BPF purpose isn't to make matching, is to filter the input/output signals to the desired bandwidth. I'm a little confuse and would like you to confirm my ideas, to help I made a sketch: The BPF and the BALUN next the transceiver are attached to this one. The other BALUN is attached to the antenna. The communication is bidirectional, so the BPF source and load resistance should be the same. If I were using that scheme for reception or transmission only, that BALUN next to the transceiver wouldn't be necessary, I think. But, because it needs to work in the both directions, I have to ensure the source and load resistance are the same, they will "switch their positions" when I switch from RX to TX and vice-versa, so if they are equal, no problem. Because the filter, at the antenna side, is connected to a 50 Ohm transmission line, I'm going do design the BPF for a 50 Ohm source and load resistance. This way I need a BALUN between the BPF and the transceiver to match (or maybe this could be achieved with a conventional impedance transformer, perhaps more expensive...) Am I thinking correct? I had never done anything similar to this, maybe there are simpler and cheaper solutions. I would appreciate very much you feedback.