Ham Amateur Radio Technician Practice Exam

What is an advantage of vertically stacking horizontally polarized Yagi antennas?

1. It increases the bandwidth

2. It narrows the main lobe in elevation

3. It allows for higher gain

4. It improves side lobe suppression

The correct answer is: It narrows the main lobe in elevation

Stacking horizontally polarized Yagi antennas vertically is a technique used by amateur radio operators to enhance performance, particularly in the elevation pattern. By vertically stacking these antennas, the main lobe in elevation is narrowed, resulting in a focused beamwidth. This means that the antenna can transmit and receive signals more effectively in a specific direction, making it advantageous for long-distance communication. Narrowing the elevation pattern helps in achieving better signal quality and reduces the reception of unwanted noise and interference from other directions. This setup is particularly useful in reducing multipath interference, where signals take different paths to the receiving antenna, which can cause distortion and other issues. The design essentially allows operators to have a more precise and effective communication capability, particularly at certain elevations where signals might travel better, such as in instances requiring line-of-sight propagation. While other factors such as higher gain and improved side lobe suppression may also be benefits of various antenna configurations, the primary and direct effect of vertically stacking these antennas specifically is the ability to narrow the main lobe in elevation. This precision becomes crucial for maximizing signal strength and clarity in targeted communications.