*Question G9D02:
What is the feed point impedance of an end-fed half-wave antenna?*  

*Correct Answer is  D: Very high*  

### AI Response: (may contain errors)  

An end-fed half-wave antenna, also known as an EFHW, is a type of antenna where the feed point is located at one end of the half-wave element. The feed point impedance of such an antenna is determined by its position along the antenna.

1. **Correct Answer: Very high**

   - The feed point impedance of an end-fed half-wave antenna is very high because the end of a half-wave dipole is a voltage maximum and a current minimum. This results in a high impedance at the feed point. The impedance can be several thousand ohms.

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

   - **Choice A: Very low**  
     The impedance is not very low at the end of a half-wave antenna. A low impedance would be found at a current maximum, such as the center of a half-wave dipole, not at the end.

   - **Choice B: Approximately 50 ohms**  
     A 50-ohm impedance is typical for the center feed point of a half-wave dipole, not for an end-fed configuration.

   - **Choice C: Approximately 300 ohms**  
     A 300-ohm impedance might be associated with a folded dipole or a specific matching condition, but not with an end-fed half-wave antenna.

3. **Useful Rule of Thumb:**

   - For a half-wave dipole:
     - Center feed point: Low impedance (around 50-75 ohms)
     - End feed point: High impedance (several thousand ohms)

Understanding these impedance characteristics is crucial for matching the antenna to the transmitter or feed line, often requiring an impedance matching network for efficient operation.