a design of the novel coupled-line bandpass filter using defected ...

19with( i − )⎡12 1 π ⎤−pi= jcos ⎢sinjη+ ⎥⎣2n⎦η⎛1 1⎞sinh sinh⎝nε ⎠−1= ⎜ ⎟In (2-38) p i is a pole at location i, all the transmission zeros of S ( p)21arelocated at infinity. Therefore, the Chebyshev filter is sometimes referred to as all-polefilter. The pole locations for the Chebyshev case lie on an ellipse in the left half-plane.2The major axis of the ellipse is on the jΩ-axis and its size is 1+ η ; the minor axis ison the σ-axis and is of size η. Example of the pole distribution is shown, for n = 5, inFigure 2-9.FIGURE 2-9 Pole distribution for Chebyshev response