*Question E9H10:
How can the output voltage of a multiple-turn receiving loop antenna be increased?*  

*Correct Answer is  C: By increasing the number of turns and/or the area enclosed by the loop*  

### AI Response: (may contain errors)  

To understand how to increase the output voltage of a multiple-turn receiving loop antenna, let's analyze the correct answer and the other choices.

### Correct Answer: 
**C: By increasing the number of turns and/or the area enclosed by the loop**

- **Explanation**: The output voltage of a loop antenna is directly related to the number of turns in the loop and the area enclosed by the loop. The induced voltage in a loop antenna can be expressed as:

$$
V = N \cdot B \cdot A \cdot \omega
$$

where:
- $V$ = induced voltage
- $N$ = number of turns
- $B$ = magnetic flux density (related to the strength of the incoming electromagnetic field)
- $A$ = area of the loop
- $\omega$ = angular frequency of the incoming signal

Increasing either the number of turns ($N$) or the area ($A$) will increase the induced voltage, making this choice correct.

### Why the Other Choices are Incorrect:

- **A: By reducing the permeability of the loop shield**  
  - **Explanation**: Reducing the permeability of the loop shield would actually decrease the effectiveness of the loop in capturing magnetic fields. A higher permeability allows the loop to better couple with the magnetic field, thus increasing the induced voltage. Therefore, this choice is incorrect.

- **B: By utilizing high impedance wire for the coupling loop**  
  - **Explanation**: While using high impedance wire may affect the overall impedance of the circuit, it does not directly increase the output voltage of the loop antenna. The output voltage is more influenced by the physical characteristics of the loop itself (turns and area) rather than the impedance of the wire used. Thus, this choice is also incorrect.

- **D: All these choices are correct**  
  - **Explanation**: Since choices A and B are incorrect, this choice cannot be correct either. 

### Summary:
To effectively increase the output voltage of a multiple-turn receiving loop antenna, focus on increasing the number of turns and/or the area enclosed by the loop. This is the most effective method based on the relationship between these factors and the induced voltage.