Extra exam question E9H11

WhyA cardioid pattern's single null is the feature that makes it useful for direction-finding antennas. A cardioid pattern's single, well-defined null is exactly what makes it useful for a direction-finding antenna, giving an unambiguous bearing without the 180-degree confusion a bidirectional pattern (like a plain small loop) would create, answer B. A very sharp peak, broadband response, and a high radiation angle aren't the specific feature that makes a cardioid pattern valuable for DF work, the single clean null is what matters here.