# Directional antenna (log-periodic or horn)

> Used with an RF meter or analyser to find the bearing of a dominant source, distinguishing a tower on one azimuth from a neighbour's access point on another.

- Canonical URL: https://emfbase.com/meters/directional-antenna
- Collection: Instruments
- Record id: `meters:directional-antenna`
- Status: verified
- Last verified: 2026-08-12
- JSON: https://emfbase.com/api/meters/directional-antenna
- Also known as: log periodic antenna, yagi, horn antenna

## Key values

- **Band covered:** antenna dependent
- **Quantities measured:** power density
- **Typical price:** $100–$2000

## Detects

- Direction of arrival of the dominant signal
- Whether shielding one facade will help

## Cannot detect

- Isotropic exposure — a directional antenna deliberately understates everything off-axis

## What to insist on

- Published antenna factor across the band, so readings convert to field strength
- Frequency coverage matched to the meter

## Related records

- [RF spectrum analyser](https://emfbase.com/meters/spectrum-analyser): Resolves a reading into its constituent services and frequencies — the only way to attribute an RF level to a specific band, operator or device.

## Sources

- `fcc-oet65` Federal Communications Commission, Office of Engineering and Technology (1997). *OET Bulletin 65: Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields*. https://www.fcc.gov/general/oet-bulletins-line — government, link checked 2026-08-12

Data licence: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Dataset version 2026.08.1. Retrieved from EMFBase, https://emfbase.com.

This record is reference data, not medical or legal advice. Regulatory limits, scientific guidelines and precautionary values are labelled separately and answer different questions.