G9A08: SWR on feed line: If the SWR on an antenna feed line is

Q: If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end of the feed line is adjusted to present a 1:1 SWR to the transmitter, what is the resulting SWR on the feed line?

The correct answer is B: 5:1. The correct answer is B: 5:1. If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end is adjusted to present 1:1 SWR to the transmitter, the resulting SWR on the feed line is still 5:1. The matching network only matches at its location - it doesn't change the SWR on the feed line itself. For amateur radio operators, this is important to understand. Understanding this helps when using matching networks.

Updated: Dec 9, 2025 | Source: 2023-2027 Question Pool | Topic: G9A

G9A08G9A

If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end of the feed line is adjusted to present a 1:1 SWR to the transmitter, what is the resulting SWR on the feed line?

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Deep Dive: G9A08

The correct answer is B: 5:1. If the SWR on an antenna feed line is 5:1, and a matching network at the transmitter end is adjusted to present 1:1 SWR to the transmitter, the resulting SWR on the feed line is still 5:1. The matching network only matches at its location - it doesn't change the SWR on the feed line itself. For amateur radio operators, this is important to understand. Understanding this helps when using matching networks.

Why Other Answers Are Wrong

Option A (1:1): Incorrect. SWR on feed line isn't 1:1 - the matching network only matches at its location, it doesn't change the feed line SWR. 1:1 is only at the matching network. Option C: Incorrect. SWR isn't between 1:1 and 5:1 depending on characteristic impedance - the feed line SWR is still 5:1. Characteristic impedance doesn't change SWR. Option D: Incorrect. SWR isn't between 1:1 and 5:1 depending on reflected power - the feed line SWR is still 5:1. Reflected power doesn't change SWR.

Exam Tip

Matching network at transmitter = feed line SWR unchanged (still 5:1). Think 'M'atching 'N'etwork = 'M'atches at 'N'etwork location only. Matching network only matches at its location - it doesn't change SWR on feed line itself. Not 1:1, not between - just 5:1 still.

Memory Aid

Matching network at transmitter = feed line SWR unchanged (still 5:1). Think 'M'atching 'N'etwork = 'M'atches at 'N'etwork only. Matching network only matches at its location - it doesn't change SWR on feed line. Important to understand.

Real-World Example

Feed line has 5:1 SWR. You add a matching network at the transmitter end, adjusting it to present 1:1 SWR to the transmitter. The matching network matches at its location, but the feed line still has 5:1 SWR - the mismatch still exists on the feed line. The matching network doesn't fix the feed line SWR, it only matches at the transmitter.

Source & Coverage

Question Pool: 2023-2027 Question Pool

Subelement: G9A

Reference: 2023-2027 Question Pool · G9 - Antennas and Feed Lines

Key Concepts

SWR on feed line Matching network 1:1 SWR to transmitter Feed line SWR unchanged

Verified Content

Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G9A topic.