RF Filter Calculator: Microstrip Low Pass & Bandpass
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This RF filter calculator is designed for microstrip filter calculations. It covers both low pass and bandpass RF filter calculations commonly used in microstrip designs. Both pi filter and T filter section filter topologies are supported.
Microstrip Low Pass Filter Calculator
This is a simple LC-based RF lowpass filter calculator of order N equal to 3.
Example:
- INPUTS: Fc = 1182.5 MHz, Z0 = 50 Ohm
- OUTPUTS: L = 1.34e-8 Henries, C = 5.38e-12 farads
Microstrip Low Pass Filter Formula
The following equations are used in the RF lowpass filter calculator of order N equal to 3. Figure 1 depicts lowpass pi filter and T filter section topologies.
This simple RF filter calculator, made of L and C components, can be very handy.
Figure 1: Lowpass Pi and T Filter Topologies
Microstrip Bandpass Filter Calculator
This is a simple LC-based RF bandpass filter calculator of order N equal to 3.
Example:
- INPUTS: f1 = 1024.5 MHz, f2 = 1060.5 MHz, Z01 = 50 Ohm
- OUTPUTS: L1 = 4.42e-7 Henries, L2 = 1.319e-10 Henries, C1 = 5.276e-14 farads, C2 = 1.76e-10 Farads
Microstrip Bandpass Filter Formula
Figure 2 depicts bandpass pi filter and T filter section topologies. Following are the equations for the RF bandpass filter topologies mentioned above.
Figure 2: Bandpass Pi and T Filter Topologies
- L1 = [ Z0/ (Pi*(f2-f1)) ] … Henries
- L2 = [ Z0*(f2-f1) / (4*Pi*f2*f1) ] … Henries
- C1 = [ (f2-f1) / (4*Pi*f2*f1*Z0) ] … Farads
- C2 = [ 1 / (Pi*Z0*(f2-f1) ] … Farads
To further understand the concepts behind the Microstrip filter calculator, you can refer to a step-by-step RF filter design example. This design article covers a microstrip-based RF/Microwave Low Pass Filter design example, along with Kudora’s identities, Richard’s transformation, and a filter coefficients table for Chebysev LPF.