*Question G6B04:
What is a typical upper frequency limit for low SWR operation of 50-ohm BNC connectors?*  

*Correct Answer is  C: 4 GHz*  

### AI Response: (may contain errors)  

To determine the typical upper frequency limit for low SWR (Standing Wave Ratio) operation of 50-ohm BNC connectors, we need to consider the specifications and performance characteristics of these connectors.

### Correct Answer: C: 4 GHz

1. **Why the correct answer is correct:**
   - BNC connectors are designed for a frequency range that typically extends up to about 4 GHz. At this frequency, they maintain a low SWR, which is essential for efficient power transfer and minimal signal reflection. Beyond this frequency, the performance of the connector can degrade, leading to higher SWR and potential signal loss.

2. **Why the other choices are incorrect:**
   - **A: 50 MHz**: This frequency is well within the operational range of BNC connectors. However, it is much lower than the typical upper limit, making it an incorrect choice.
   - **B: 500 MHz**: While BNC connectors can operate at this frequency, it is still below the typical upper limit of 4 GHz. Thus, it is not the best answer.
   - **D: 40 GHz**: This frequency is significantly above the operational capabilities of standard BNC connectors. At this frequency, the connectors would likely experience high SWR and poor performance, making this choice incorrect.

### Useful Information:
- **SWR and Connector Performance**: A low SWR (typically less than 2:1) is desired for efficient transmission. As frequency increases, the SWR can rise if the connector is not rated for those frequencies.
- **General Rule of Thumb**: For RF connectors, always refer to the manufacturer's specifications for the maximum frequency rating to ensure optimal performance.

In summary, BNC connectors are suitable for applications up to 4 GHz, making option C the correct answer for low SWR operation.