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Sci.Electronics.Basics -> VSWR doesn't matter? But how about "mismatch loss"?
There are 44 messages in this thread.
You are currently looking at messages 40 to 44.
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Author: Cecil MooreDate: 21:37 31-03-07
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Tom Ring wrote:
> Duh, life always violates it locally, but makes the sum total of entropy
> higer than it would have been. You aren't the idiot you appear, I hope.
I guess I should have added a smiley face.
--
73, Cecil http://www.w5dxp.com
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Author: joseph2kDate: 04:56 05-04-07
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Cecil Moore wrote:
> billcalley wrote:
>> Now my head *really* hurts! This is a VERY confusing subject, to
>> say the least. (And I also thought antenna tuners actually had a
>> *loss* due to their limited Q...I think I'm going to change careers
>> now and just become a pet groomer; or perhaps simply give up
>> completely and work at Radio Shack).
>
> Real-world antenna tuners do have a loss but we previously
> specified a lossless system. Of course, real world tuners
> and transmission lines suffer losses but we all just live
> with those losses while striving to minimize them. The point
> is that an antenna tuner reflects most of the reflected
> energy back toward the load thus accomplishing a mismatch
> gain that offsets some, if not most, of the mismatch loss.
> High SWR transmission lines are indeed lossier than flat
> matched transmission lines of the same material.
> --
> 73, Cecil, w5dxp.com
Close but no cigar. The (now often automatic) antenna tuner is used to
transform the native impedance to the transmitter to match the conjugate
transformed impedance of the antenna at the transmitter end of the
transmission line. The effective result is that the incident energy
arriving at the antenna "sees" a matched load and goes out to free space
instead of bouncing off the transmission line to antenna interface.
This is also why better antennas have reasonable (not far off matching
impedance) characteristic impedances; they do not require matching networks
physically placed at the antenna itself.
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.
--Schiller
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Author: joseph2kDate: 05:11 05-04-07
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Cecil Moore wrote:
> Buck wrote:
>> Cecil Moore <nospam@w5dxp.com> wrote:
>> Please explain your antenna and radio. I am assuming you have a solid
>> state rig with an so-239 connector on it for the basic and then you do
>> what?
>
> Hi Buck, Please check out my associated web page and then
> ask me anything that you don't understand.
>
> http://www.w5dxp.com/notuner.htm
>
> Contrary to what you may have been told, you can change
> the 50 ohm SWR seen by your transmitter by changing the
> length of the 450 ohm ladder-line.
Now that is a "real" ham radio antenna system, screwampus but it provably
works, and is repeatable (by others).
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.
--Schiller
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Author: joseph2kDate: 05:16 05-04-07
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Richard Clark wrote:
> On 29 Mar 2007 13:10:46 -0700, "billcalley" <billcalley@yahoo.com>
> wrote:
>
<snip>
> It does matter if you lack a tuner (in more ways that one). Most
> discussion of "mismatch loss" omits such matters as tuners as it is a
> separable issue. Combining these topics raises your chance of
> confusion.
>
> 73's
> Richard Clark, KB7QHC
Heartily agreed.
--
JosephKK
Gegen dummheit kampfen die Gotter Selbst, vergebens.
--Schiller
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