Filters

1. Characteristics of Filters

2. T- Network
Characteristic Impedance for a T network is Z0T =
Open-circuit impedance Zoc =
Short-circuit impedance Zsc =
Z0T = 𝑍𝑜𝑐 ∗ 𝑍𝑠𝑐

3. π- Network
Characteristic Impedance for a π network is Z0π =
Open-circuit impedance Zoc =
Short-circuit impedance Zsc =
Z0π = 𝑍𝑜𝑐 ∗ 𝑍𝑠𝑐

4. Propagation Constant
The propagation constant γ of the network in the figure is

6. By equating both the characteristic impedance equations

9. CHARACTERISTIC OF FILTERS
• A filter transmits or passes a desired range of frequencies without
loss and attenuates all undesired frequencies.
• The propagation constant γ = α + jβ
• Where α is the attenuation constant and β is the phase constant.
We know that

14. CONSTANT-k LOW PASS FILTER
• A T or p network is said to be of the constant k type if Z1 and Z2 are opposite types of reactances satisfying the
relation
Z1Z2 = k2