Based On The Tem Mode Of Transmission Line Filter Design

For all kinds of microwave systems,microwave filters are the essential passive components in the need of band selectivity and interference supperession.In recent decades,Advances are made in whether various filter design theory, or engineering design approaches.There are various types of media available for implementation.lt falls upon the developers to properly apply them.Coaxial line and stripline,are two common kinds of transmission line medium with their operating mode TEM,and quite suitable for designing filters and other passive components. Compared to microstripline,their closed structure result in lower energy dissipation, and they have higher power capacity. The same operating mode determine their suit for designing wide-band passive components.Based on the filter relative theory and design approaches,the coaxial low-pass filter and stripline high-pass filter are demonstrated.In this paper,mainly three parts as follows are presented.First of all,the basic theory on filter designing and coaxial line and stripline transmission characteristics are described.Next, to start from the lumped-element lowpass proptype,the feasibility of introducing cross-couple is discussed. Then a cross-couple lowpass filter is designed in use of the square coaxial line.At last, the optimum model is introduced.In the circuit proptype, connecting lines between two short stubs are non-redundant. And, an example of the stripline highpass filter with this model and its fractional bandwidth of125%is demstrated.