**m Derived Band Stop Filter:**

The m Derived Band Stop Filter can be derived from the prototype band elimination filter section in the exactly same way as the m-derived band pass filter.

The m Derived Band Stop Filter section is as shown in the Fig. 9.37.

The relationship between frequency of infinite attenuation (f_{1∞ }, f_{2∞}) and cut-off frequencies (f_{1}, f_{2}) is given by,

If the frequency of resonance is f_{0} then it is the geometric mean of two cut-off frequencies as well as of two frequencies of infinite attenuation.

Simplifying equation (1),

**Variations of Characteristic Impedance (Z**_{0}) , Attenuation Constant (α) and Phase Constant (β) with Frequency:

_{0}) , Attenuation Constant (α) and Phase Constant (β) with Frequency:

The variations of characteristic impedance Z_{0}, attenuation constant α and phase shift β with frequency is as shown in the Fig. 9.38 (a), (b) and (c)