# Narrowband signal · Concept

> A radio signal confined to a very small range of frequencies, which nature rarely makes.

Source: https://mysteriesdept.com/concepts/CPT0DECW03SJNS9/narrowband-signal  
Publisher: Mysteries Department  
Licence: CC BY 4.0 (credit Mysteries Department and link the page)  

---

[Concepts](https://mysteriesdept.com/concepts)Narrowband signal

Concept · radio astronomy · in 3 mysteries

# Narrowband signal

A radio signal confined to a very small range of frequencies, which nature rarely makes.

[Wow! signal](https://mysteriesdept.com/mysteries/wow-signal)[Tabby's star (KIC 8462852)](https://mysteriesdept.com/mysteries/tabbys-star)[1I/'Oumuamua](https://mysteriesdept.com/mysteries/oumuamua)

Natural radio sources spread their power over wide bands; transmitters concentrate it in a few hertz. A signal much narrower than any known natural emission is therefore the classic sign of technology, and the reason the Wow! signal was flagged in 1977. Interference from Earth is narrowband too, which is why a signal must be seen again, from another telescope, before it counts.

## Where it comes up

**[Wow! signal](https://mysteriesdept.com/mysteries/wow-signal)**

The 2025 reanalysis used previously unpublished archive data and found that cold hydrogen clouds produce similar narrowband signals.

[The 2025 reanalysis used previously unpublished archive data and found that cold hydrogen clouds produce…](https://mysteriesdept.com/mysteries/wow-signal/evidence/EVD0CXZ4ZCW2EQG/the-2025-reanalysis-used-previously-unpublished-archive-data)

**[Tabby's star (KIC 8462852)](https://mysteriesdept.com/mysteries/tabbys-star)**

[The Allen Telescope Array found no narrowband signal above 180 to 300 Jy in a 1 Hz channel from 1 to 10 GHz.](https://mysteriesdept.com/mysteries/tabbys-star/evidence/EVD0D8E7BBT588K/the-allen-telescope-array-found-no-narrowband-signal-above)

**[1I/'Oumuamua](https://mysteriesdept.com/mysteries/oumuamua)**

The Green Bank Telescope observed on 13 December 2017 across 1.1-11.6 GHz and found no narrowband signal, a limit of 0.08 W for an omnidirectional transmitter on the object .

## Cite it

```
Mysteries Department. (2026). Narrowband signal [Concept CPT0DECW03SJNS9]. https://mysteriesdept.com/r/CPT0DECW03SJNS9
```

Key

**CPT** 0DECW03SJNS9

Record

Concept

Field

Radio astronomy

Related

[Technosignature](https://mysteriesdept.com/concepts/CPT0DECW03KAJAY/technosignature) · [Dispersion measure](https://mysteriesdept.com/concepts/CPT0DECW040R5CS/dispersion-measure)

Version

2

Added by

[apollo](https://mysteriesdept.com/u/apollo)

**How this page is made.** The definition is the site's, in its own words. “Where it comes up” is read from the answers, methods and evidence that name the concept.

Related concepts

[Technosignature](https://mysteriesdept.com/concepts/CPT0DECW03KAJAY/technosignature)[Dispersion measure](https://mysteriesdept.com/concepts/CPT0DECW040R5CS/dispersion-measure)

The record

Every record is open data. Take this one as JSON, with its links and its history.

[JSON](https://mysteriesdept.com/api/v1/records/CPT0DECW03SJNS9)