marki microwave filter calculator

What this Marki Microwave Filter Calculator helps you do

When you are comparing microwave bandpass filters, the datasheet can be dense: center frequency, insertion loss, return loss, bandwidth definitions, and skirt steepness can all appear in separate plots. This calculator condenses the most-used relationships into one quick view so you can make faster engineering decisions.

It does not replace full electromagnetic simulation or measured S-parameter review. Instead, it gives a practical first pass for tradeoff analysis and requirement checks.

Inputs and outputs explained

1) Center frequency and 3 dB bandwidth

From these two values, the calculator determines:

• Lower 3 dB edge frequency
• Upper 3 dB edge frequency
• Fractional bandwidth (FBW)
• Loaded Q estimate (Q_L = f₀ / BW)

2) Insertion loss

Insertion loss in dB is converted to approximate power transmission and dissipation percentages, helping you quickly estimate signal budget impact in a receiver or transmitter chain.

3) Return loss

Return loss is converted into reflection coefficient magnitude and VSWR. This is useful when checking how well the filter is impedance-matched to neighboring blocks (mixers, amplifiers, switches, and couplers).

4) Optional 20 dB bandwidth

If you provide 20 dB bandwidth, the calculator computes shape factor. A lower shape factor usually indicates steeper transition skirts and better adjacent-channel rejection behavior.

Core formulas used

• f_low = f₀ − BW/2
• f_high = f₀ + BW/2
• FBW (%) = (BW / f₀) × 100
• Loaded Q = f₀ / BW
• Power transmission (%) = 10^−IL/10 × 100
• |Γ| = 10^−RL/20
• VSWR = (1 + |Γ|) / (1 − |Γ|)
• Shape factor = BW_20dB / BW_3dB (optional)

How to use this in real RF design work

During part selection

Start with system targets (LO feedthrough, blocker rejection, IF image suppression, etc.). Enter rough passband numbers and verify whether your chosen filter class is likely narrowband, moderate, or wideband. This gives immediate insight before opening a full CAD model.

During link budget planning

Insertion loss directly affects noise figure in receive chains and available output power in transmit paths. The transmission percentage shown by the calculator is a quick way to explain filter penalty to non-RF stakeholders.

During interface checking

VSWR and reflection estimates are useful for identifying potential mismatch ripple and gain flatness concerns when cascaded with amplifiers or mixers.

Practical notes for microwave filter evaluation

• Always confirm whether bandwidth is specified at 1 dB, 3 dB, or another reference level.
• Check test conditions: connector type, fixture de-embedding, temperature, and power level can shift measured responses.
• Review out-of-band rejection over the full spectrum relevant to your application, not just one offset point.
• If phase linearity matters (modulated signals, timing systems), inspect group delay variation in passband.
• For production designs, include tolerance and temperature margin beyond nominal calculator values.

Example scenario

Suppose you target a 10 GHz center frequency with 500 MHz bandwidth, 1.8 dB insertion loss, and 15 dB return loss:

• 3 dB passband edges: approximately 9.75 GHz to 10.25 GHz
• Fractional bandwidth: 5%
• Loaded Q: 20
• Transmitted power: about 66%
• VSWR: around 1.43:1

That quickly tells you this is a moderate-bandwidth filter with manageable, but non-trivial, passband loss.

Final takeaway

This Marki microwave filter calculator is designed as a fast engineering companion for front-end architecture and component screening. Use it early for sizing and communication, then validate with full S-parameter analysis, layout-aware simulation, and lab measurements before finalizing hardware.