RF Power Converter | Qucs-S S-parameter Viewer Documentation

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# RF Power Converter

## Overview

Converts RF power values between linear and logarithmic units, supporting both 50 Ω and 75 Ω system impedances. All conversions route through watts as an intermediate unit.

## Conversion Pipeline

    Input (any unit) → Watts → Output (any unit)

## Supported Units

Unit | Type | Reference
--- | --- | ---
W | Linear | —
mW | Linear | —
dBm | Logarithmic | 1 mW
dBμV | Logarithmic | 1 μV
dBmV | Logarithmic | 1 mV
V | Linear | Z₀

Each of dBμV, dBmV, and V is available in both 50 Ω and 75 Ω variants.

## Formulas

### To Watts

Unit | Formula
--- | ---
W | P_W = P
mW | P_W = P × 10⁻³
dBm | P_W = 10^((P - 30) / 10)
dBμV (75 Ω) | P_W = 10^((P - 138.75) / 10)
dBmV (75 Ω) | P_W = 10^((P - 78.75) / 10)
V (75 Ω) | P_W = V² / 75
dBμV (50 Ω) | P_W = 10^((P - 136.99) / 10)
dBmV (50 Ω) | P_W = 10^((P - 76.99) / 10)
V (50 Ω) | P_W = V² / 50

### From Watts

Each formula above is simply inverted. For example:

    dBm  = 10 × log₁₀(P_W) + 30
    V    = √(P_W × Z₀)

## Input Parameters

- Power

- Input unit

- Output unit

## Example

Input:

- Power: 0 dBm

- Output unit: dBμV (Z₀ = 75 Ω)

Calculation:

    To watts:
      P_W = 10^((0 - 30) / 10) = 10^(-3) = 0.001 W

    From watts to dBμV (75 Ω):
      dBμV = 10 × log₁₀(0.001) + 138.75
           = -30 + 138.75
           = 108.75 dBμV

Output: `108.75 dBμV (Z₀ = 75 Ω)`