Explanation: A direction finder adjusted to take unilateral bearings uses a reception pattern that eliminates the 180-degree ambiguity often found in simpler direction-finding systems (like a basic loop antenna). This is typically achieved by creating a cardioid (heart-shaped) reception pattern. A cardioid pattern is characterized by a single, very deep null (a point of minimum reception) in one specific direction. While it receives signals with varying strength from all other directions, it effectively "blanks out" or fails to receive from that single null direction. This deep null is precisely what is rotated to pinpoint the bearing of a signal source. Thus, the direction finder is capable of receiving signals from all but that one specific direction of its null.