Talk:Quarter-wave impedance transformer

A fact from Quarter-wave impedance transformer appeared on Wikipedia's Main Page in the Did you know column on 18 August 2009 (check views). The text of the entry was as follows:

Did you know... that a quarter wave impedance transformer can make an electrical open circuit look like a short circuit?

A record of the entry may be seen at Wikipedia:Recent additions/2009/August.

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Resonance[edit]

I have removed the reference to resonance concerning transforming open circuits to short circuits. If it is mentioned in the article it needs to be explained at length what resonance means in this context. I originally started writing a section on resonance for this article, but then realised I was describing stubs, which is a different article. That article could certainly use the material and it is now on my to do list. It is not necessary to introduce the complication of resonance here. λ/4 is a function of frequency and a shorted length of transmission line resonates at the frequency where its length is λ/4. In other words, stating that the length is λ/4 is synonymous with stating that it is at its resonant frequency, making the introduction of the concept superfluous. The frequency dependance of λ/4 is explicitly stated in the next paragraph. SpinningSpark 18:07, 11 August 2009 (UTC)[reply]

Okay, but I can imagine a reader or two that would appreciate the clarification of having resonance mentioned and explained further in terms of short circuit. I appreciate that it's on your To Do list. Binksternet (talk) 18:16, 11 August 2009 (UTC)[reply]

I think there should be a detailed explanation at stub (electronics), which is where this becomes important. Once that's in place, we can put in a mention/link here. Resonance does not really clarify this article, but I agree readers may be interested. I am not against having it mentioned per se, just that throwing it in without explanation does not help the reader. SpinningSpark 21:13, 12 August 2009 (UTC)[reply]

Purpose?[edit]

The lede needs a definition of purpose. The whole article seems to avoid its purpose with sentences that do not complete. 174.118.142.187 (talk) 14:39, 17 January 2013 (UTC)[reply]

I am not quite sure what you mean. It's purpose is to create the dual of an impedance network. This is already stated in the lede. The applications section give several examples of its use, nothing is being avoided. Improvements in wording would be welcome. Spinning Spark 22:31, 17 January 2013 (UTC)[reply]

The lede says "The device presents at its input the dual of the impedance with which it is terminated". Is this not contrary to your explanation above? I think this is out of my realm on this one. I don't understand the item enough to make valid technical edits. Thanks. 174.118.142.187 (talk) 04:53, 22 January 2013 (UTC)[reply]

Why do you think it is contrary? But either way, the lede still says what it does. By the way, this article has a lot more on applications than, say, the resistor article which says virtually nothing.

I would think there would be a difference between the "impedance network" and the "impedance with which it is terminated". Are they not at opposite ends of the transformer? I never referred to applications. I only asked about function. 174.118.142.187 (talk) 04:56, 23 January 2013 (UTC)[reply]

It can be terminated with a single lumped impedance or a network of any complexity whatsoever. At the input end, the impedance seen will be the dual of that network so impedance and impedance network can be used interchangeably in this context. For instance a simple example; an inductor and resistor in series will be transformed into a capacitor and conductance in parallel. Spinning Spark 07:36, 23 January 2013 (UTC)[reply]

OK Thanks! It is starting to make sense, now, when I read it. As I said... not my field. I got out of RF as a kid, electronic gadgets when ICs went to .05" pins and now being a software user and grid P&C systems have eaten my life. :) 174.118.142.187 (talk) 05:00, 25 January 2013 (UTC)[reply]

Some typical applications might be useful in the leading paragraph; sure it's a nice development of transmission line theory, but it's got more application than filling time in a lecture. SHould we not put some examples such as "One application of the quarter-wave impedance transformer is to match the low output impedance of an RF power transistor to the impedance of a transmission line or antenna.", or something like that. --Wtshymanski (talk) 14:59, 25 January 2013 (UTC)[reply]

Clumsy[edit]

I've don't think I've ever seen a clumsier and unhelpful introduction to an article. A significant use of quarter-wave transformers is to match a load to a source impededance and this is achieved when the quarter wave line impedance is the square-root of the product of the load and source impedances. It takes pen and paper to work that out from the article. BTW, as well as applications in network and circuit matching, that's how AR coatings work - with impedance replaced by refractive index. 86.162.175.214 (talk) 16:46, 8 November 2023 (UTC)[reply]