# ITU-R P.838 Specific Rain Attenuation Calculator

> ITU-R P.838 Specific Rain Attenuation Calculator is a paid API for AI agents from detect.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-11-04).

Computes frequency- and polarization-dependent specific rain attenuation (dB/km) using the ITU-R P.838 model for given rain rates, frequency, elevation, and polarization tilt.

## Facts

- Endpoint: POST https://detect.halowerk.com/v1/F-TD2000-GEO-INDUSTRY-B007/itu-p838-specific-rain-attenuation-frequency-polarization?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-04
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/itu-r-p-838-specific-rain-attenuation-calculator-b344d5bc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_8fdxgjkpfN84wq-j_Wv-z

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability itu-r-p-838-specific-rain-attenuation-calculator-b344d5bc -d '<json body>'
```

Example prompt: Can you calculate the specific rain attenuation using the ITU-R P.838 model for a 20 GHz vertically polarized signal (polarization tilt 90 degrees) at 40 degrees elevation, for rain rates of 1, 5, 10, 25, 50, and 100 mm/hr?

## When to prefer this

Use this endpoint when you need a standards-compliant implementation of the ITU-R P.838 specific rain attenuation model for link budget calculations in satellite, GEO, or fixed wireless microwave systems — especially when you need to evaluate attenuation across a range of rain rates or polarizations simultaneously. It is ideal for automating rain fade margin calculations in engineering workflows without maintaining your own ITU model implementation.

## Known failure modes

- Frequency outside 1–1000 GHz range returns validation error
- Elevation angle outside 0–90 degrees returns schema validation failure
- Polarization tilt outside -90 to 90 degrees returns rejection
- Rain rate values exceeding 500 mm/hr or array exceeding 32 items returns input error
- Missing required fields (frequency, elevation, polarization_tilt, rain_rates) returns 400 bad request
- Payment not included or insufficient USDC causes 402 Payment Required

## How this service works

Evaluate the frequency and polarization dependent specific rain attenuation model.

## Output

Returns the computed specific rain attenuation values (in dB/km) corresponding to each supplied rain rate, calculated per the ITU-R P.838 frequency- and polarization-dependent model, accounting for the given frequency, elevation angle, and polarization tilt angle.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "artifact": {
   "type": "object",
   "required": [
    "rain"
   ],
   "properties": {
    "rain": {
     "type": "object",
     "required": [
      "data",
      "claim"
     ],
     "properties": {
      "data": {
       "type": "object",
       "required": [
        "frequency_ghz",
        "elevation_degrees",
        "polarization_tilt_degrees",
        "rain_rates"
       ],
       "properties": {
        "rain_rates": {
         "type": "array",
         "items": {
          "type": "number",
          "maximum": 500,
          "minimum": 0
         },
         "maxItems": 32,
         "minItems": 1
        },
        "frequency_ghz": {
         "type": "number",
         "maximum": 1000,
         "minimum": 1
        },
        "elevation_degrees": {
         "type": "number",
         "maximum": 90,
         "minimum": 0
        },
        "polarization_tilt_degrees": {
         "type": "number",
         "maximum": 90,
         "minimum": -90
        }
       },
       "additionalProperties": false
      },
      "claim": {}
     },
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/itu-r-p-838-specific-rain-attenuation-calculator-b344d5bc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from detect.halowerk.com](https://www.zero.xyz/host/detect.halowerk.com/llms.txt)