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Featured articleDistributed-element filter is a featured article; it (or a previous version of it) has been identified as one of the best articles produced by the Wikipedia community. Even so, if you can update or improve it, please do so.
Main Page trophyThis article appeared on Wikipedia's Main Page as Today's featured article on July 17, 2010.
Did You Know Article milestones
DateProcessResult
February 18, 2010Good article nomineeListed
May 2, 2010Peer reviewReviewed
July 6, 2010Featured article candidatePromoted
Did You Know A fact from this article appeared on Wikipedia's Main Page in the "Did you know?" column on November 16, 2009.
The text of the entry was: Did you know ... that distributed element filters can use a wide and varied library of printed elements including butterfly and clover stubs?
Current status: Featured article

Rewrote the lead

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The old lead had some problems.

A distributed element filter is an electronic filter designed for frequencies above the VHF band or thereabouts. At these frequencies the wavelengths of the operative signals are shorter than the size of the device being constructed and it is no longer possible to use the more familiar lumped element model. Filters and other passive circuitry are instead designed using the distributed element model in which the components of the circuit are treated as being transmission lines, which indeed, they effectively are.

Note that at the top of VHF band the wavelength in air is ~1 meter. Lumped elements crap out about here but clearly "wavelengths of the operative signals" are not "shorter than the size of the device being constructed". I've also added some helpful wikilinks. I think the new language flows a bit better as well but YMMV. JPatterson (talk) 20:34, 15 February 2010 (UTC)[reply]

Things to improve

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  • Front figure: "for suppressing non-TEM modes of transmission" needs a cite. Adding a note on image width would help understanding the size - not everyone knows this connector type. Image file needs a better description, preferably explaining why rubber seal (moisture ?).
I have addressed the "through holes for TEM mode" issue. Image size is a bit problematic; it is not my image so I cannot retake it with a rule included. It would, of course, be possible to estimate the size from some of the circuit structures, but that is almost the definition of OR. I am against explaining the rubber seal (it is to give the enclosure an IP rating because the product is intended for outdoor use) - this is going way off-topic; there are any number of features that could be explained here. The only one mentioned, the through holes, are only described because they can easily be mistaken for a filter structure. SpinningSpark 20:48, 8 April 2010 (UTC)[reply]
Regarding the via fences: there will be an internal metal lid cast with a pattern of walls on the underside, which corresponds to the pattern of via-fences. This lid is clamped down tightly onto the circuit by a large number of bolts - notice all the screw holes associated with the via fences (it can't have been screwed down very well in this example as the walls have not made a visible indentation in the metallization). The via fences connect the base of the walls to the ground-plane, so forming a number of near perfectly isolated enclosures, communicating only where the microstrip passes through a notch in the cast walls. This internal lid is in addition to a simple external lid which makes a seal with the rubber gasket.--catslash (talk) 10:41, 29 April 2010 (UTC)[reply]
Regarding the photo: I've just put a more close-up view of a (just) a filter at File:Microstrip-bandpass-filter.jpg. I was going to use this to illustrate edge-coupling on the microstrip page, but never got around to writing about it. I haven't put the picture on this page, as you may feel that the existing one is better - take a look and see what you think. --catslash (talk) 16:35, 29 April 2010 (UTC)[reply]
Nice picture. That would be great for the parallel-coupled lines section. I don't think we should expand on via fences in this article, it is only mentioned for clarification purposes. I have red-linked it with the intention that an article should go there someday. SpinningSpark 07:35, 30 April 2010 (UTC)[reply]
OK. I just felt that the phrase for suppressing non-TEM modes of transmission though strictly speaking true, is rather misleading. --catslash (talk) 11:55, 30 April 2010 (UTC)[reply]
  • There is some imbalance between figure captions - one cites references and others don't. I probably understand why, but this could be picked up at FAC.
There is usually no need to give citations to image captions unless they introduce facts not in the main text. All the figures here are described in the text where a citation is given. I have made an exception for figure 2 because it is a composite from a number of different sources and I wished to make it clear which filter structure came from which source. SpinningSpark 20:30, 9 April 2010 (UTC)[reply]
  • Add history subsection?
I am actively looking into this. The history of the various technologies (co-ax, stripline, microstrip, waveguide etc) is well documented, mostly of them starting in radar in WWII and the filters in these technologies followed shortly after their first use. However, sources dealing with distributed element filtering as a general topic are a bit harder to find and I need to see if enough material can be gathered to write a worthwile section. SpinningSpark 20:30, 9 April 2010 (UTC)[reply]
I have now started a history section. There is still a bit more that could go in, but I think the point is now addressed. SpinningSpark 18:13, 11 April 2010 (UTC)[reply]
done SpinningSpark 12:21, 11 April 2010 (UTC)[reply]

Prose comments by Cryptic C62

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Unresolved comments

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Here are some comments on the article's prose intended to help make the article accessible and precise:

  • "they have the drawback that it is impossible to create an ideal open circuit" Because I'm a physics nerd, I automatically assume that "ideal" has some special meaning, as is the case for ideal gas. What meaning is it intended to convey here?
Yes, exactly in the sense of an ideal gas which perfectly obeys some law of physics. Even more relevant, it is the same sense in which we talk of ideal voltage or current generators in electrical analysis. Specifically here is meant a circuit element through which zero current flows regardless of the voltage across it. SpinningSpark 17:56, 1 July 2010 (UTC)[reply]
Is it ever possible to create an ideal circuit? I only ask because ideal gasses do not exist, so I would assume that the same is true of ideal circuits. If such is the case, then the highlighted sentence doesn't really make any sense. If it is possible to create an ideal circuit, I think this sentence would benefit from a wikilink (I couldn't find any appropriate articles) or a brief explanation—the article should be accessible to everyone, not just to circuitry nerds. --Cryptic C62 · Talk 00:06, 4 July 2010 (UTC)[reply]
Ideal circuit elements do not in reality exist but it is perfectly valid to examine how well a real component corresponds to the ideal. Electrical analysis is entirely based on networks of ideal elements so it is not only unavoidable, but actually helpful, to discuss ideal elements here and there. Even when it is desired to model a non-ideal component, this is done by adding additional ideal elements to its network representation - a real non-ideal resistor might be modelled, for instance, by adding a capacitor in parallel, and an inductor in series with it. In the case of a printed line being left open-circuit, this is a non-ideal open-circuit because of the unavoidable dielectric effect of the board on which it is printed. Consequently, this non-ideal open circuit is frequently modelled as shown in figure 4b as a parallel capacitor. This is to be compared to a line terminated with a short-circuit achieved with a strap through a via hole to the ground plane beneath. To be sure, this will not be an ideal element either, the strap must possess some resistance for instance. However, it is close enough to the ideal to be treated as ideal for most design purposes. The dielectric effect causing such a problem for open-circuits is not a problem here since anything in parallel with a short-circuit is still a short-circuit; the capacitive effect has been shorted out. I will try tweaking the wording though, to make this a bit clearer. SpinningSpark 09:47, 4 July 2010 (UTC)[reply]

More to come. As you make changes in the article, please respond below individual concerns so I know which are done and which need further discussion. Thanks! --Cryptic C62 · Talk 00:52, 15 June 2010 (UTC)[reply]

  • As you have not struck this, does it mean that your edit summary of "final comments" is untrue?
The review is now complete. Distributed element filter has earned my stamp of approval:
Feel free to contact me if you want a review for any other articles you're working on. --Cryptic C62 · Talk 03:12, 28 July 2010 (UTC)[reply]

Great article

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Nice job. I know electronics, but not microwave techniques, and I found the article very readable. Wizzy 16:14, 17 July 2010 (UTC)[reply]

Good work. Howver, I see a way to further improve the presentation. For example, the citation starts in the text with the number 4, but the reference list starts from 1. Also the reference section does not contain the entire informnation so that to be able to find that reference in on-line library. — Preceding unsigned comment added by 199.64.72.253 (talk) 12:54, 23 December 2014 (UTC)[reply]

The references are numbered automatically by the Wikimedia software and cannot be changed. They are numbered in the order they appear in the source text. Refs #1, #2, and #3 are in the "block converter" sidebox. In the source this is above the introductory text (to ensure that it appears to the side, and not beneath, the opening text) so those refs get numbered first and hence the first ref in the text is #4. The full citation information is contained in the bibliography section below the references. It is organised this way to avoid the full citation having to be entered each time the same reference is used. Not all references are online, but for book references one can often find an online preview by clicking on the ISBN number. This will take you to a page listing numerous book catalogues. The most useful ones for previewing are Google Books and Amazon, both of which allow limited preview for selected books. The most useful for finding a copy in a library is the WorldCat site. SpinningSpark 14:42, 23 December 2014 (UTC)[reply]

super duper long img alt

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@Spinningspark: I recall a recent WT:FAC discussion suggesting that img alt text should be short short. This has the longest I've ever seen... clocking in at nearly 500 words. ♦ Lingzhi2 (talk) 15:50, 2 August 2019 (UTC)[reply]

I agree with you. At one time the standard was to write long alt text, almost an audio description of the image. The current thinking is that it should be minimalist unless there is some information to impart that is not covered in the text or caption. Nowadays I generally put in one word alts like "photograph" or "diagram"; alt text should always exist, even if only one word, to prevent screen readers from reading out the file name, which is generally less than useful. SpinningSpark 22:40, 2 August 2019 (UTC)[reply]
hey added a clear because on my laptop the first word of the paragraph after the image (i.e., " The") gets separated from the rest of the sentence and isolated on the same line as the image, before the image. As for alt text, I dunno how someone with a screen reader would respond to the 5 minute descriptions. ♦ Lingzhi2 (talk) 00:34, 3 August 2019 (UTC)[reply]
You must be using a very low res monitor, something like 800×600 px for that orphaning to happen. I've added a fix that should stop it happening. As I already said, there's no objection from me if you want to remove the long alt texts. SpinningSpark 01:07, 3 August 2019 (UTC)[reply]