Common YouTube Confusions: SWR: How Standing Waves ACTUALLY Behave!
Updated: October 18 2025 — Educational analysis of TheSmokinApe’s “SWR Explained” video. It cites a 40-year-old book on antenna impedance; RF understanding has evolved greatly since then. Let’s see what holds up—and what modern theory tells us instead.
Analyzing TheSmokinApe’s SWR Explanation — Myths vs. Modern Reality
▶ 00:00 — The 40-Year-Old Book Reference
Myth: The referenced material from the 1980s still fully describes modern transmission-line behavior.
Reality: While the classic ARRL-era texts were foundational, they assume lossless lines, ideal impedances, and purely resistive loads. Modern RF measurement and simulation have shown how line loss, dielectric absorption, and real-world current distribution all modify those simple charts. Treat old SWR tables as historical, not prescriptive.
▶ 01:00 — SWR Isn’t a Power Ratio
Myth: SWR expresses how much power is “sent” versus “reflected.”
Reality: SWR is a voltage amplitude ratio along the line. Power relationships derive from |Γ|², not from the SWR itself. It measures standing-wave depth, not watt division. Confusing the two leads to false assumptions about loss or radiation efficiency.
▶ 01:50 — “100 % Transmitted Power”
Myth: You always transmit 100 % of your power; mismatch only decides what bounces back.
Reality: Modern transmitters monitor load impedance and reduce output (fold-back) automatically to protect finals. “100 % transmitted” just means the PA is sourcing its setpoint, not that all of it reaches the antenna.
▶ 02:30 — Getting Nervous at 1.5 : 1 SWR
Myth: SWR above 1.5 : 1 is dangerous for equipment.
Reality: Nearly all modern rigs handle up to 2.5–3 : 1 safely without user concern. Their output networks and protective logic automatically reduce drive or compensate. There’s no need for anxiety—efficiency changes only a few percent.
▶ 03:20 — What SWR = 2 Really Means
SWR = 2 corresponds to a reflection coefficient |Γ| = 1/3. Only 11 % of forward power is reflected; 89 % reaches the load.
Myth: SWR = 2 wastes half your power.
Reality: Even with a 2 : 1 mismatch, the delivered power drop is only about 0.5 dB—barely noticeable. Line loss, not mismatch, usually dominates efficiency.
Quick Reference Table
| SWR | |Γ| | Reflected % | Delivered % |
|---|---|---|---|
| 1.5 | 0.20 | 4 % | 96 % |
| 2.0 | 0.33 | 11 % | 89 % |
| 3.0 | 0.50 | 25 % | 75 % |
| 5.0 | 0.67 | 44 % | 56 % |
▶ 06:00 — Causes of High SWR
Myth: High SWR always means a bad antenna.
Reality: SWR simply reports mismatch between line and load. It can stem from height, surroundings, or feedline impedance—not antenna “badness.” Even 1:1 readings can hide poor efficiency if losses are high.
▶ 06:50 — Standing Waves Don’t Move
The standing-wave envelope is stationary, but the RF energy flows both directions within it.
Myth: Standing waves mean energy is trapped on the line.
Reality: They’re the interference pattern of two traveling waves—forward and reflected. Energy still flows and is partially re-radiated after each reflection. SWR describes amplitude pattern, not energy confinement.
▶ 11:00 — Conjugate Matching Explained
A conjugate match ensures the rig sees a resistive 50 Ω. The tuner adjusts the complex impedance at its input but leaves feedline SWR unchanged.
Myth: The tuner “fixes” SWR everywhere.
Reality: It only fixes what the radio sees. The line between tuner and antenna keeps its same mismatch; reflected energy is re-reflected back toward the antenna.
▶ 11:40 — Reflected Power Destroys Finals
Myth: Reflected power bounces into the PA and burns components.
Reality: Damage occurs from over-voltage or current stress, not the reflection itself. Fold-back circuits limit drive well before failure. The “reflected power kills radios” fear dates from tube days, not solid-state rigs.
▶ 12:00 — Coax Voltage Breakdown
Myth: Coax “burns up” from reflected power.
Reality: Dielectric breakdown happens when voltage peaks exceed insulation strength—usually from high power and extreme SWR, not ordinary mismatches. Rated peak voltage matters more than SWR value.
▶ 12:40 — Inductive vs Capacitive Mismatch
Too-long antennas show inductive reactance; too-short ones capacitive. Both increase mismatch magnitude but affect phase differently. Tuners compensate easily either way.
▶ 06:00 — Dipole Height and Impedance
Myth: Lowering a dipole “improves” efficiency because SWR drops.
Reality: The impedance change just moves toward 50 Ω through ground coupling—it doesn’t radiate better. Efficiency depends on losses, not SWR alone.
▶ 13:40 — Final Takeaway
Myth: Perfect 1:1 SWR is the only “good” match.
Reality: Any SWR under about 2.5 : 1 is perfectly acceptable. Modern rigs tune or tolerate it without issue. Chasing 1:1 by adding lossy components can make things worse—efficiency, not meter reading, should guide design.
Mini-FAQ
- Does a tuner lower SWR on the coax? — No. It only matches what the transmitter sees.
- Can reflected power return to the antenna? — Yes, through re-reflections and re-radiation.
- Does high SWR always mean big loss? — Not necessarily; loss depends on coax type and length.
- What really harms finals? — Over-voltage or current stress, not “bouncing watts.”
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