SWR, is .5 Is there THAT MUCH OF A change from 1 to 1.5??
Ok, talking with my friends father the other day and My antenna build was the topic. He said yea, 1.5 isn't bad at all for a fresh build but couldn't I tune it more?
My reply to him was yes, As of now have not wanted to start nipping copper little bits at a time yet. And I was pretty happy with 1.5 SWR. He said "you know the difference of .5 right? Its night and day".
So looking for input from everyone here. He was doing his own antennas and all during CB days. and for CB, but with HAM radios is .5 really going to improve range that much? Xmit and Receive ?
CB myth. The answer is no.
I came back and edited this to expound on the answer. First, it would depend on why you had the SWR. Antenna reactance, mismatch of the cable at the transmitter feedpoint, mismatch of impedance at the antenna feedpoint, Proximity to passive radiators, etc, etc, etc. As you see, there are some you can 'tune' out and others you cannot. So if the best you can achieve is 1.5 to 1, then great. SWR in and of it self is a misleading indication of antenna system performance. You can have a SWR of 1 to 1 and be burning up your coax with line loss and radiating 1 of your 100 watts. So your friend needs to read more about what he's teaching as truth. And you need to find a better Elmer.
Last edited by KB1NXE; 06-01-2011 at 01:47 AM.
Reason: Added more info
The US is based on Capitalism.
Not Socialism or Communism.
If you want to be part of the 1%, Work Harder! Make it the 2%!
No one is stopping you... But Yourself.
An SWR of 1.0 might be a big tip-off that you've left the dummy load attached.
Well now you've learned a very important lesson. Don't ever go to that guy for antenna advice again.
Originally Posted by KJ6OJL
"Night and day" is nonsense. Some solid state rigs will actually work better into a 1.5:1 50 ohm SWR. Tube final amps just don't care. Mostly it's just pretty neutral as long as you're not folding back power on your transmitter.
The only time I ever shoot for lower than 1.5:1 or so is if I won't be able to cover the whole band under 2:1 if I don't do that. I don't have an autotuner so that's just a matter of convenience.
SWR is one of many indications, and by far not a very important one unless the antenna is so terrible that a tiny bit of added loss will break it.
For a VHF antenna, the important stuff is really:
-Height above ground and all local obstructions
-Transmission line loss
-Go back to #1
A bad mismatch will increase line loss, which is bad. But if the line has very low loss to begin with (or is very short) then mismatch means very little.
HEIGHT is the most important parameter.
I'd much rather have a zero-gain 1/4-wave ground plane at 100' than a "6 dB gain" antenna down close to the ground. The difference is astronomical on VHF.
Lucky for me I've been able to "demonstrate" this for many years, since for a long time I've had telescoping towers.
It would have to be pretty accurate meter before I would trust the difference between 1:1 vs 1.5:1.
Be sure to listen for my beacon on 28.278.8 MHz
The difference of a 1.5:1 VSWR mismatch loss equates to 0.18 dB.
Another way to look at this loss difference is one S-unit equals 6 dB and the loss we are talking about equates to around 1/22nd of a single (*1) S-unit.
Don't strain your eyes too hard to see the difference!
73 de Charles - KC8VWM
North American QRP CW Club #3159, SKCC# 5752
I can't say I know how accurate his is.
Pretty much new in box from year and years ago.
Old radio shack unit. But his worked i got the same one
At the swapmeet which ended up being dead. So I need to
Still get my own swr meter.
Originally Posted by WA4OTD
Most amateur SWR meters are really pretty good. This does NOT include CB-type meters, only real wideband meters.
Originally Posted by KJ6OJL
They might be off like reading a 1.2:1 when it is 1:1, but nothing remotely close to being 1.5:1 when it is 1:1....or vice versa.
The entire topic of SWR has most Hams, and virtually all CBers, totally befuddled. For example in some cases a mismatch can decrease system losses. In other cases it doesn't hurt at all, and in some cases SWR can hurt much worse than we might think.
As a general rule if SWR is less than 1.3 or 1.4 to 1, we can pretty much ignore it. Sometimes we can ignore SWR if it is 100:1. Sometimes 1.5:1 can be a problem. It just all depends.
And just to throw another spanner into the works....
The idea is to tune an antenna for RESONANCE or X=0 on the frequency you want. When you've got X=0, SWR is very rarely 1:1 yet X=0 is where you want the antenna but SWR seems to be what more people are obsessed with.