*Question E9C09:
Which of the following describes a G5RV antenna?*  

*Correct Answer is  A: A wire antenna center-fed through a specific length of open-wire line connected to a balun and coaxial feed line*  

### AI Response: (may contain errors)  

The G5RV antenna is a popular multi-band wire antenna used by amateur radio operators. Let's break down why the correct answer is choice A and why the other options are incorrect.

### Correct Answer: A
- **Description**: The G5RV antenna is a wire antenna that is center-fed through a specific length of open-wire line (also known as ladder line or twin lead). This open-wire line acts as a matching section and is connected to a balun, which then connects to a coaxial feed line.
- **Functionality**: The design allows the antenna to operate on multiple bands, typically including 80, 40, 20, 15, and 10 meters, by using the open-wire line to transform impedances and the balun to transition from balanced to unbalanced feed lines.

### Why Other Choices Are Incorrect:
- **Choice B: A multi-band trap antenna**
  - **Explanation**: A trap antenna uses parallel resonant circuits (traps) to isolate sections of the antenna for different frequency bands. The G5RV does not use traps; it relies on the open-wire line for impedance matching across bands.
  
- **Choice C: A phased array antenna consisting of multiple loops**
  - **Explanation**: A phased array antenna uses multiple elements, often loops or dipoles, arranged to create a directional pattern through phase differences. The G5RV is a single wire antenna, not a phased array.
  
- **Choice D: A wide band dipole using shorted coaxial cable for the radiating elements and fed with a 4:1 balun**
  - **Explanation**: This describes a different type of antenna design, sometimes known as a coaxial dipole or sleeve dipole, which uses coaxial cable as part of the radiating element. The G5RV does not use coaxial cable as radiating elements; it uses wire and open-wire line.

### Key Points:
- **Balun**: A device that converts between balanced and unbalanced signals, crucial for connecting the open-wire line to coaxial cable.
- **Open-Wire Line**: Acts as a matching section to help the antenna work on multiple bands by transforming impedances.

Understanding the structure and function of the G5RV antenna helps in recognizing its unique design and differentiating it from other types of antennas.