A planar filtering crossover for three intersecting channels

A planar filtering crossover is proposed for three intersecting channels in this paper. It is constructed with three dual-mode ring resonators. The even and odd modes are coupled in three groups, to support the second-order bandpass filtering response for each channel. The isolation between different channels are achieved by using the orthogonality of even and odd resonant modes, with properly designing the internal and external couplings. The prototype shows reasonable performance of both intra-channel filtering and inter-channel isolation.