---
title: "Calculate physical dimensions of a dipole antenna for a given frequency. Returns half-wave or quarter-wave element length in metres, feet, and inches. A half-wave dipole is the most common resonant antenna with approximately 2.15 dBi gain. A quarter-wave monopole (ground plane antenna) is half the length and is widely used in handheld radios and vehicle-mounted systems. Use this before building or purchasing an antenna to verify element length for your operating frequency."
method: POST
path: "/api/dipole"
tags: ["rf"]
---

# Calculate physical dimensions of a dipole antenna for a given frequency. Returns half-wave or quarter-wave element length in metres, feet, and inches. A half-wave dipole is the most common resonant antenna with approximately 2.15 dBi gain. A quarter-wave monopole (ground plane antenna) is half the length and is widely used in handheld radios and vehicle-mounted systems. Use this before building or purchasing an antenna to verify element length for your operating frequency.

`POST /api/dipole`

## Request

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

## Request body

- object
  - `freq_mhz` number, required: Operating frequency in megahertz (MHz)
  - `type` 'half_wave' | 'quarter_wave': Antenna type: half_wave dipole or quarter_wave monopole

## Response `200`

Computed result for dipole

- object
  - `result` object, required
    - `length_m` number, required: Element length in metres
    - `length_ft` number, required: Element length in feet
    - `length_in` number, required: Element length in inches
    - `wavelength_m` number, required: Full wavelength in metres
  - `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)