This ought to be worth discussion.

[Marconi]

3. The SWR in a feed line cannot be changed,
adjusted, or controlled in any practical manner
by varying or adjusting the line length.
TRUE

This is one of the most misunderstood concepts
in antennas, and we could spend pages
explaining the theory. The simple answer is
again that SWR on the line is determined by the
ratio of the load impedance to the characteristic
impedance of the line. Line length (assuming
low feed line loss) CANNOT change the SWR.
We can discuss the mathematical proof over a
Coke. There is something of a trick to this
question. There’s a difference between the SWR
on the line and the effective INPUT impedance
seen at the input connector to the antenna
system. Changing the line length (thus electrical
line length) can change the input impedance
making it easier for a tuner to match the line to
the transmitter.

Hey MrS or anybody else, these are not a trick questions.

What can change (one word), with a less than perfect match at the feed point, when the feed line length is altered in length that appears as a change in SWR at the transmitter, and what (one word) causes this to happen?

 

[bob85]

doc,
you are wrong, the meter does not HAVE to be anywhere and it is not comparing whats behind it to whats in front of it,

there is " one answer and one answer only " to your question but alas its not the answer you were thinking of,
don't backpeddle by saying its a very good idea, theres a BIG difference between very good idea and have to/only one answer,

transmitter output impedance not been 50ohms does not cause high vswr on an otherwise sound system "that is common on broadband no tune amplifiers" as you post/argue on the forums,

if you do not agree with whats been said then post proof from respected sources, thats how we learn,

alternatively start your own threads if you want to talk crap, don't disrupt other peoples,
failure to do so will always result in threads getting way off track with pages of argument,

this is exactly why CEBIK did not want to get on here and educate people about the sigma4 style antennas, i don't care who believes that and who don't, its the truth as told by him to me.

 

[Marconi]

I was taught that standing wave is a necessary part of RF wave function, and that it is the degree of magnitude that is the only significant factor we have to consider regarding VSWR, and that anything within a range of 1.01-2 can be useful in this regard. zero value does not exists with VSWR as a ratio.

Meaning we will always have some SWR that exists on the feed line (albeit minimal is desirable), or the feed line will be useless for the transmission of AC to convert to RF with a proper load.

 

[Captain Kilowatt]

this is exactly why CEBIK did not want to get on here and educate people about the sigma4 style antennas, i don't care who believes that and who don't, its the truth as told by him to me.

Cebik? :blink: As in L.B. Cebik aka W4RNL? When was this supposedly to have taken place Bob?

 

[hookedon6]

Cebik? :blink: As in L.B. Cebik aka W4RNL? When was this supposedly to have taken place Bob?

i was kinda wondering about that too:tongue:

 

[hookedon6]

...Meaning we will always have some SWR that exists on the feed line (albeit minimal is desirable), or the feed line will be useless for the transmission of AC to convert to RF with a proper load.

???? "SWR" doesn't physically exist,...... it's just a math ratio.

the RESULTS of VSWR do exist, you are confusing the two.


you are talking "apples & oranges"

 

[Marconi]

???? "SWR" doesn't physically exist,...... it's just a math ratio.

the RESULTS of VSWR do exist, you are confusing the two.


you are talking "apples & oranges"

I think you're right the term I should have used was Standing Wave where I used SWR. Thanks for catching my mistake.

 

[MrSuburban]

 

[bob85]

Cebik? :blink: As in L.B. Cebik aka W4RNL? When was this supposedly to have taken place Bob?

captain,
when i emailed LB about the sigma4 we went back and forth a few times, he told me that he did not want to get involved with the pages of meaningless argument such antennas can generate due to people not understanding how they work,
he told me about the none aparent co-linear effect and i went away looking for info, sadly he went silent key before i got to talk to him further .

 

[Captain Kilowatt]

FB Bob. I knew he went SK about three years ago so that was why I was asking. I didn't know your discussions went that far back about that antenna.

 

[bob85]

doc, thanks

captain,
we have been talking about it for years off and on, it keeps cropping up.

 

[Moleculo]

All,

Can we please learn to have a debate without all of the personal insults and attacks? It really does not help promote the site, and it lends nothing to the technical aspects of the discussion.