*Question E9C06:
What is the effect of adding a terminating resistor to a rhombic or long-wire antenna?*  

*Correct Answer is  B: It changes the radiation pattern from bidirectional to unidirectional*  

### AI Response: (may contain errors)  

Adding a terminating resistor to a rhombic or long-wire antenna affects its radiation pattern. Here's how:

1. **Correct Answer: B - It changes the radiation pattern from bidirectional to unidirectional**

   - **Explanation**: A rhombic or long-wire antenna without a terminating resistor typically radiates in two opposite directions, making it bidirectional. By adding a terminating resistor at the far end of the antenna, the energy that would normally be reflected back is absorbed by the resistor. This prevents the formation of standing waves and allows the antenna to radiate primarily in one direction, making it unidirectional.

2. **Why the other choices are incorrect**:

   - **Choice A**: "It reflects the standing waves on the antenna elements back to the transmitter"
     - **Explanation**: The terminating resistor actually absorbs the energy, preventing reflection and standing waves, rather than reflecting them back to the transmitter.

   - **Choice C**: "It changes the radiation pattern from horizontal to vertical polarization"
     - **Explanation**: The polarization of an antenna is determined by its physical orientation and design, not by the presence of a terminating resistor. The resistor affects directionality, not polarization.

   - **Choice D**: "It decreases the ground loss"
     - **Explanation**: Ground loss is related to how the antenna interacts with the ground, not the presence of a terminating resistor. The resistor affects the radiation pattern, not the ground loss.

In summary, the terminating resistor in a rhombic or long-wire antenna is used to absorb energy and prevent reflections, thereby changing the radiation pattern from bidirectional to unidirectional.