N10-009 Question 174
Single answerAntennas: Omnidirectional vs. directionalA network technician is asked to extend wireless connectivity from the main office building to a warehouse located 250 meters away across an open parking lot. The warehouse only needs connectivity in one fixed location, and the company wants to minimize signal leakage into neighboring businesses on either side of the parking lot. Which antenna choice is the BEST fit for this requirement?
- A
Install omnidirectional antennas on both ends so the signal radiates evenly in all directions
- B
Install directional antennas on both ends to focus the RF energy along the building-to-warehouse path
- C
Install an omnidirectional antenna at the office and a directional antenna at the warehouse so clients can roam more easily
- D
Increase the transmit power on existing omnidirectional antennas instead of changing antenna types
Show answer and explanation
Correct answer: B
Explanation
For a link between two known, fixed points, directional antennas are generally the best choice because they focus RF energy toward the intended endpoint rather than spreading it broadly. Omnidirectional antennas are better suited for serving multiple client devices around an access point, such as in an office floor or lobby. In real deployments, this distinction is a core wireless design principle: choose omnidirectional antennas for broad area coverage and directional antennas for point-to-point or point-to-specific-area coverage. Vendor wireless design guides and industry best practices consistently recommend directional antennas when the goal is to extend connectivity to a specific remote building while limiting interference and signal leakage outside the intended path.
- A. Incorrect.
This is incorrect. Omnidirectional antennas radiate RF energy in a broad horizontal pattern, which is useful for covering clients in many directions around an access point. In this scenario, the target is a single fixed warehouse location across an open area, so broadcasting in all directions is inefficient and increases unwanted signal exposure to adjacent properties.
- B. Correct.
This is correct. Directional antennas concentrate RF energy in a specific direction, making them the preferred choice for point-to-point or narrowly focused links between two fixed sites. Using directional antennas on both ends improves signal strength along the intended path and helps reduce RF spillover to neighboring businesses.
- C. Incorrect.
This is incorrect. A mixed antenna design like this does not best meet the stated requirement. Roaming is not relevant because the warehouse connection is for one fixed location, not mobile clients moving between coverage cells. An omnidirectional antenna at the office would still radiate unnecessary signal in multiple directions, which conflicts with the goal of limiting leakage.
- D. Incorrect.
This is incorrect. Raising transmit power does not solve the core issue of antenna pattern. Higher power with omnidirectional antennas can actually worsen interference and signal leakage by increasing RF energy in every direction. Best practice is to select the proper antenna type for the coverage objective rather than relying only on transmit power adjustments.