There was a table on here a long time ago showing the TX loss as SWR got further away from 1:1.
Does anyone have that handy?
Does anyone have that handy?
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SWR to TX Loss Table?
- Thread starter The Jerk
- Start date
https://n6pet.com/power-loss-various-swr/
and circa 1 010 000 other results from google
There is more accurate: https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf
and circa 1 010 000 other results from google
There is more accurate: https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf
So, to perspective:
@ 2:1 VSWR .... 100 watts at Transmitter = 89 watts radiated @Antenna (less cable loss)
Guess what? Receive station will NEVER Hear the difference
Even @ 5:1 you have only around 3 db loss (barely noticeable to human ear)
Thus the quest for the perfect 1:1 (even below 1.7:1) is rather ridiculous.
VSWR (antenna-theory.com)
Quote: VSWR alone is not sufficient to determine an antenna is functioning properly.
Quote: VSWR alone is not sufficient to determine an antenna is functioning properly.
Be careful with these tables. What they call "loss" isn't actually loss. The correct term would be "reflected", as that much power will be reflected, and I get how some would think that since it was reflected it was "lost", but in reality not all of it is, and in most cases, most of it actually isn't.
Its a difficult concept to explain, and I get why a lot of people never get there, but its true. If you want some hard numbers, both lower and higher loss when running coax into a load, I can get them for you. I would suggest doing a search for coax loss calculator, look for the qsl.net page, and play around with it. It uses data from several manufacturers data sheets to predict what said coax will do under certain conditions, and I have verified many of its results myself.
The DB
Its a difficult concept to explain, and I get why a lot of people never get there, but its true. If you want some hard numbers, both lower and higher loss when running coax into a load, I can get them for you. I would suggest doing a search for coax loss calculator, look for the qsl.net page, and play around with it. It uses data from several manufacturers data sheets to predict what said coax will do under certain conditions, and I have verified many of its results myself.
The DB
Many CB style SWR meters have the percentage loss on the meter itself. Look at the bottom of the SWR scale, that is the percentage loss, 0,4,11, and 25. You just have to do the percentage loss math yourself.
Better to learn to use a cross needle swr meter which shows all this information at a glance.
For those who aren't sure on these types, look where the 2 needles cross over the red lines representing the swr value numbers 1.0 to 5:1 and beyond.
In the example pic we'll use a 100 watt scale on the meter values for ease of math.
The green and red cross needles meet at 2.1 swr.
The green power needle is showing 40 watts forward power and the red reflected (loss) needle is showing just under 5 watts
So subtracting the 2 values, the real power out is around 35.5 watts which according to the swr charts is correct at an 11% power loss.
So with cross needle meters there's no need for charts unless you want to see the full scope at once.
Better to learn to use a cross needle swr meter which shows all this information at a glance.
For those who aren't sure on these types, look where the 2 needles cross over the red lines representing the swr value numbers 1.0 to 5:1 and beyond.
In the example pic we'll use a 100 watt scale on the meter values for ease of math.
The green and red cross needles meet at 2.1 swr.
The green power needle is showing 40 watts forward power and the red reflected (loss) needle is showing just under 5 watts
So subtracting the 2 values, the real power out is around 35.5 watts which according to the swr charts is correct at an 11% power loss.
So with cross needle meters there's no need for charts unless you want to see the full scope at once.
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Thanks, it was just a curiosity mainly.
I have a 102 mounted directly to the base, with a 2:1 SWR and a barefoot Uniden 76. I couldn't remember where the SWR became a problem, seems 2:1 won't be a problem.
I have a 102 mounted directly to the base, with a 2:1 SWR and a barefoot Uniden 76. I couldn't remember where the SWR became a problem, seems 2:1 won't be a problem.
Try that 102 inch out. Even with the 2:1 SWR I am sure you will be happy with the results of your TX/TX. Size does matter. I ran one for a while on my 94' Forester with the old ball mount through drivers rear fender. Motorola spring, SWR was around 2.1 on the ends of the band and 1.6 at best in center. I never messed with it other than I tried adding a counterpoise. I was more than than pleased with the TX/RX.
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