Design of a symmetric rectangular waveguide T-junction with in-phase and unequal power split characteristics

A rectangular waveguide T-junction divider with unequal power-split and in-phase design is proposed. The power-division is realized by an offset septum and a matching window. Physically, two output branches are kept symmetric w.r.t. the input port. To obtain in-phase performance caused by the offset of septum, the width of output ports is varied to control the phase velocity in each branch. This ensures equal time-of-arrival of waves propagating to two output ports. Hence, the in-phase characteristic can be obtained without destroying the physical symmetry of T-junction. A phase difference of less than 8° over the frequency range 14.0-17.0GHz can be achieved with a return loss better than 23dB.