Design of New Quad-Channel Diplexer With Compact Circuit Size

摘要

New compact quad-channel diplexer (1.5/2 GHz and 2.4/3.5 GHz) using the coupled stepped impedance resonators (SIRs) is proposed. The quad-channel diplexer is composed of two pairs of coupled SIRs with impedance ratio $({rm K} > 1)$ and the source-load coupling lines. By tuning the impedance ratio and length ratio $(alpha)$ of SIRs, the resonant modes can be easily determined so as to implement a two-order bandpass filter with very close dual-passbands. The source-load coupling lines are designed to correspond to the quarter-wavelength at the center frequency of first passband for each output port. The proposed quad-channel diplexer is showing a simple configuration, an effective design method and a small circuit size.