2.3 Given a scenario, select and configure wireless devices and technologies
Antennas
📘CompTIA Network+ (N10-009)
What Is a Directional Antenna?
A directional antenna is an antenna that focuses its wireless signal in one direction instead of spreading the signal equally in all directions.
- It provides stronger coverage in the direction it is pointed.
- It does not provide much coverage behind or to the sides.
- It is used when you want to send Wi-Fi over a specific path.
Directional antennas are the opposite of omnidirectional antennas, which spread the signal in all directions.
Key Benefits of Directional Antennas
✔ Longer Range
Concentrates the signal, allowing it to travel farther.
✔ Stronger Signal Quality
Useful when you need a precise and stable wireless link.
✔ Better Security
Because the signal does not spread everywhere, it reduces the chance of unauthorized access.
✔ Reduced Interference
Since the signal is focused, it avoids picking up unnecessary signals from all around.
Why Use Directional Antennas? (Exam-Relevant Scenarios)
Directional antennas are chosen when:
- You want to connect two buildings using a point-to-point link.
- You want Wi-Fi to cover a long hallway or corridor.
- You want to connect distant outdoor Wi-Fi devices (like APs on different sites).
- You want to send wireless signals across long distances with minimal loss.
These are common IT uses that the exam expects you to know.
Common Types of Directional Antennas
CompTIA Network+ expects you to know the main types and when to use them.
1. Yagi Antenna
- Narrow beam, long range.
- Often used for point-to-point connections.
- Good when you need to connect two distant wireless devices in a fixed direction.
2. Parabolic (Dish) Antenna
- Highly focused beam.
- Extremely long range.
- Used when you need very long-distance wireless links.
3. Patch / Panel Antenna
- Flat, rectangular shape.
- Medium-range directional coverage.
- Used for:
- Covering hallways,
- Connecting nearby buildings,
- Focusing Wi-Fi in a specific direction indoors or outdoors.
4. Sector Antenna
- Covers a specific sector, usually 60°–120°.
- Used in:
- Large campuses
- Outdoor Wi-Fi networks
- Environments where you divide coverage into “sectors” for better control
How Directional Antennas Work (Simple Explanation)
Directional antennas focus their power into a narrow beam.
When an AP uses a directional antenna:
- More power goes where it is needed.
- Less power is wasted in other directions.
- The result is a high-gain, long-distance wireless link.
This is why directional antennas have higher gain (dBi) values compared to omnidirectional antennas.
Important Terms for the Exam
1. Gain (dBi)
- Represents how strong the antenna signal is.
- Directional antennas have high gain because they focus energy.
2. Beamwidth
- The angle the antenna covers.
- Narrow beamwidth = longer distance
- Wide beamwidth = more coverage area but shorter distance
3. Line-of-Sight (LoS)
- A clear path with no major obstacles.
- Directional antennas often require LoS for proper performance.
4. Point-to-Point vs Point-to-Multipoint
- Point-to-Point: Connects two fixed locations (requires highly directional antennas).
- Point-to-Multipoint: One central antenna beams out to multiple receivers (uses sector or panel antennas).
When to Select a Directional Antenna (N10-009 Scenario-Based)
You should choose a directional antenna when:
✔ You need a high-distance wireless link, especially between buildings
Example in IT: connecting an office building to another using outdoor APs.
✔ You want to focus Wi-Fi signal down a hallway or warehouse aisle
Example in IT: improving signal in long corridors.
✔ You want to avoid signal leakage
Example in IT: limiting Wi-Fi from spreading outside secure areas.
✔ You want to reduce interference
Example in IT: avoiding interference from nearby networks.
Directional Antenna Limitations
Although very useful, directional antennas also have limits:
✘ Limited coverage
Only covers the direction it is aimed at.
✘ Requires precise alignment
If aimed incorrectly, the signal becomes weak.
✘ Not ideal for general-purpose Wi-Fi
A regular office usually needs omnidirectional antennas instead.
Directional Antennas vs Omnidirectional Antennas
| Feature | Directional | Omnidirectional |
|---|---|---|
| Signal Direction | One direction | All directions |
| Range | Long | Short/Medium |
| Ideal for | Point-to-point links | General indoor coverage |
| Interference | Low | Higher |
| Security | Higher | Lower |
Network+ wants you to recognize which antenna type matches a scenario.
Configuration Considerations
When configuring directional antennas:
1. Align the antennas properly
Incorrect alignment reduces range and throughput.
2. Use proper mounting
Especially important for outdoor antennas.
3. Match antenna gain to requirements
Higher gain = narrower beam.
4. Ensure Line-of-Sight
Walls, trees, and buildings may weaken signals.
5. Check local regulations
High-gain antennas must obey power limits.
Exam Tips (Very Important)
✔ Directional antennas = focused signal
✔ Used for long-distance or point-to-point wireless links
✔ Higher gain (dBi) = longer range, narrower beam
✔ Types to memorize:
- Yagi
- Parabolic (Dish)
- Patch/Panel
- Sector
✔ Know when to use directional vs omnidirectional
✔ Expect scenario-based questions like:
- “Which antenna type is best for connecting two buildings?”
- “Which antenna covers a hallway?”
- “Which antenna provides long-range focused signal?”
Final Summary
Directional antennas focus Wi-Fi signals in one direction, providing long-distance, strong, and controlled wireless coverage. They are ideal for point-to-point links, long hallways, and outdoor connections. For the Network+ exam, know the types (Yagi, Parabolic, Patch/Panel, Sector), when to use them, and how directional antennas differ from omnidirectional antennas.
