Yes, in many cases you can add an outdoor antenna to your router. Here's some key information about this:

1. Compatibility:

   - Not all routers support external antennas. Check your router's specifications or manual first.
   - Look for routers with removable antennas or dedicated antenna ports.

2. Types of outdoor antennas:

   - Omnidirectional: Broadcasts signal in all directions
   - Directional: Focuses signal in a specific direction

3. Benefits:

   - Increased range and coverage area
   - Better signal strength, especially in outdoor areas
   - Can help overcome obstacles like walls or interference

4. Installation considerations:

   - You'll need to run a cable from the router to the outdoor antenna
   - Proper weatherproofing is essential
   - Placement is crucial for optimal performance

5. Legal and regulatory issues:

   - Some countries have regulations on outdoor antennas or signal strength
   - Check local laws before installation

6. Alternatives:

   - Consider a mesh network system for extended coverage
   - Wi-Fi repeaters or extenders might be easier to set up

7. Professional help:

   - For complex setups, consider hiring a professional to ensure proper installation and optimal performance

Remember, while an outdoor antenna can significantly boost your signal, it's not always necessary. Evaluate your specific needs and situation before investing in one.