Who's version of a conjugate match is that, Brune or Maxwell? I get them
mixed up.
Carl
KM1H
----- Original Message -----
From: "Gary Schafer" <garyschafer@comcast.net>
To: <jim@audiosystemsgroup.com>; <amps@contesting.com>
Sent: Thursday, May 03, 2012 7:47 PM
Subject: Re: [Amps] Mismatch loss
> "Mismatch loss" may or may not cause a system loss. It depends on the
> generator.
>
> As I stated in a previous post if there is no re-reflection (conjugate
> match) at the generator then mismatch loss will be realized the full
> amount.
> It is a real loss.
>
> If you look at a transmitter that has an isolator on its output (typical
> of
> UHF/VHF), any reflected power back toward the transmitter will not be
> re-reflected to the load/antenna but will be absorbed in the isolators
> load.
> So if your load/antenna or connector presented a 3:1 swr there would be
> 25%
> reflected power. All of that reflected power would be lost in the
> isolators
> load. A 100 watt transmitter would only provide 75 watts to the
> load/antenna.
>
> The same thing happens on the test bench as most signal generators provide
> a
> resistive source and there is never a conjugate match. Any reflected power
> from the load gets absorbed in the source and does not get re-reflected
> back
> to the load.
> Any mismatch in impedance results in loss. This is where the term mismatch
> loss comes from. The mismatch can be the result of a connector that
> presents
> a different impedance than Zo or it can be from the load that is not the
> same impedance as Zo.
> In other words any SWR will cause a loss of power reaching the load with
> this type of generator. No transmission line required.
>
> But with a typical transmitter with a tuner at its output that same 3:1
> swr
> load will receive most all of the 100 watts due to the tuner compensating
> for the mismatch back at the transmitter. It will provide a conjugate
> match
> and most all of any reflected power will be re-reflected back to the load.
> In this case the only system loss will be that of the transmission line
> loss
> with no SWR plus any additional loss in the line by the reflected power
> running back and forth on the line.
>
> 73
> Gary K4FMX
>
>
>> What you're calling "mismatch loss" is NOT loss, it is nothing more than
>> the impedance transformation that occurs in any mis-matched line. The
>> only signal LOST is that due to excess attenuation. What you're calling
>> "mismatch loss" is entirely the result of where along the line the
>> signal is sampled or retrieved, and the "mismatch loss" can be
>> eliminated either by changing the line length or transforming the
>> impedance.
>
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