Due to the significant phase slope difference between the two paths, the in-phase signal
summation occurs at the passband edges and does not have any effect on the overall response.
For long distance transmission, it is an advantage to generate carrier-suppressed signals that offset overlapping signals to reduce wave distortion, compared with an in-phase signal
As shown in Figure 4, an LO signal at the IF frequency is split into an in-phase signal
and a quadrature signal.
If the input ports (ports 1 and 1') are excited by differential-mode signals, the out-of-phase signals will be converted to in-phase signals
when they pass through the 180[degrees] swap structure, then a virtual open appears at the symmetrical line T-T' and a wideband BPF is constructed.
The first section is a power divider which provides two well-balanced equal amplitude in-phase signals
over a broad frequency range.
A signal excited on Port 2 will be evenly split into two in-phase signals
at Port 1 and Port 3, and Port 4 will be isolated.
One technique shown by Case B is to utilize the feeding ports in opposite directions and to inject two out-of-phase signals; on the other hand, the other technique shown by Case C is to utilize the feeding ports in the same direction and to inject two in-phase signals