---
title: "Convert between VSWR, return loss, and reflection coefficient — provide any one parameter and get all related impedance-mismatch metrics. Computes VSWR (voltage standing wave ratio), return loss in dB, reflection coefficient (gamma), mismatch loss, and percentage of power reflected vs transmitted. Essential for antenna matching, transmission line analysis, and RF system budgeting. Feeds into link_budget for system-level mismatch accounting."
method: POST
path: "/api/vswr"
tags: ["rf"]
---

# Convert between VSWR, return loss, and reflection coefficient — provide any one parameter and get all related impedance-mismatch metrics. Computes VSWR (voltage standing wave ratio), return loss in dB, reflection coefficient (gamma), mismatch loss, and percentage of power reflected vs transmitted. Essential for antenna matching, transmission line analysis, and RF system budgeting. Feeds into link_budget for system-level mismatch accounting.

`POST /api/vswr`

## Request

- Base URL: `https://calc.engineer`
- URL: `https://calc.engineer/api/vswr`
- Auth: none declared

## Request body

- object
  - `vswr` number: Voltage standing wave ratio (>= 1.0, where 1.0 is perfect match)
  - `return_loss_db` number: Return loss in decibels (positive value, higher is better match)
  - `reflection_coefficient` number: Reflection coefficient magnitude (gamma), 0 to 1

## Response `200`

Computed result for vswr

- object
  - `result` object, required
    - `vswr` number, required: Voltage standing wave ratio
    - `return_loss_db` number, required: Return loss in decibels (positive)
    - `reflection_coefficient` number, required: Reflection coefficient magnitude (gamma)
    - `mismatch_loss_db` number, required: Mismatch loss in decibels
    - `power_reflected_pct` number, required: Percentage of power reflected back toward source
    - `power_transmitted_pct` number, required: Percentage of power delivered to load
  - `tool` string, required
  - `version` string, required
  - `computed_at` string, date-time, required
  - `chain` object, required
    - `feeds` unknown[]
      - unknown
    - `accepts_from` unknown[]
      - unknown

## Other responses

- `400`: Validation error or invalid JSON
- `404`: Tool not found

---

[API](https://skmtc.dev/calc/apis/calc-engineer-api.md) · [All operations](https://skmtc.dev/calc/apis/calc-engineer-api/llms.txt) · [OpenAPI document](https://skmtc.dev/calc/apis/calc-engineer-api/revisions/8830480ec488?raw)