RF Filter Calculator: Microstrip Low Pass & Bandpass

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microstrip
low pass
bandpass
calculator

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

Inputs

Outputs

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.

RF Filter Calculator formula, low pass filter

Figure 1: Lowpass Pi and T Filter Topologies

Microstrip Bandpass Filter Calculator

Inputs

Outputs

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.

Microstrip Filter Calculator formula, bandpass filter

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.

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