https://frrl.wordpress.com

A site of endless curiosity

Wrapping your mind around SWR – the perfect match

with one comment

swr-reflected-forwardLast night I was listening to a couple of guys try to wrap their minds around SWR.  Very interesting.

New hams are seemingly after “the perfect match”.  An antenna tuner will make your radio happy but it provides no improvement to the natural resonance of the antenna nor the line losses of the transmission line.

And really, is a 2:1 or 3:1 match really that bad?  At a 3:1 match (depending on line loss) with a 100W transmitter you may only lose 20 watts in reflected power.  What is the difference between 100 Watts and 80 Watts at the receiving station?

On a modern radio, 1 S-Unit is 6DB.  A doubling of power is 3 DB.  So, to move an S-Meter at a receiving station 1 S-Unit one would need to quadruple the power.  So, given this, your 3:1 SWR taking your 100 W down to 80 W is not going to make any detectable difference – as long as your tuner keeps your solid-state rig happy by fooling it into thinking SWR is 1:1

Tim “the Toolman” Taylor

As Tim “the tool man” taylor would say “more power”.  There is another option to meretriciously reducing losses – and that is “more power”.  Nothing like adding a linear to deal with losses.  Doesn’t that achieve the same end goal of getting the power out?

Those that want to “wrap their minds” around SWR -we have the “perfect match” in the resources section.

Resources

https://frrl.files.wordpress.com/2009/10/understandingswrbyexample.pdf

https://frrl.files.wordpress.com/2009/10/lowswrfortherightreasons.pdf

http://www.astrosurf.com/luxorion/qsl-transmission-line2.htm

http://www.astrosurf.com/luxorion/qsl-swr.htm

Advertisements

Written by frrl

October 27, 2009 at 4:05 pm

One Response

Subscribe to comments with RSS.

  1. Thank you for providing above informational resources. I’m learning about antennas and the myth behind flat SWR in addition to the function of an antenna tuner.

    73
    KA3DRR

    Scot R. Morrison

    October 31, 2009 at 4:54 pm


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: