Talk:Circulator

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Hi, I did a little editing on this page. The diagram while pretty does not diagram a typical use of a circulator AT ALL.

Also the bizness about "Active circulators" is just plain bogus. You can subtract out a signal with an op-amp but that has absolutely nothing to do with ferrite microwave circulators. Nothing.

Hi, I'd more-or-less concur with Special:Contributions/216.70.45.162 (time to get a user-name?).

• In the diagram there is a switch, and the circulator is just used as an isolator, whereas in the text, it says that the circulator is used in place of the switch.
• The term "active circulator" gets a paltry 817 hits on Google; it probably deserves at most a passing mention here. The bit about frequency-division and time-division multiplexing is not relevant (and is confusing).

Some other observations;

• The first sentence A circulator is a passive electronic component with three or more ports in which the ports can be accessed in such an order that when a signal is fed into any port it is transferred to the next port (only), the first port being counted as following the last in numeric order. is nicked almost verbatim from the IEEE Standard Dictionary of Electrical and Electronics Terms.
• There should be some mention of non-reciprocity.
• A scattering matrix might be worth a thousand words.

--catslash 11:32, 12 September 2007 (UTC)

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Yes, please, let's either drop that picture or get a more appropriate one. The pic shows the exact opposite of the most common usage, it's using a physical switch instead of a circulator.

Also all the bizness about "active circulators" is misleading, there is no such thing, strictly speaking.

An Hac 14:06, 20 September 2007 (UTC)

Magnetic-free radio wave circulator.

Lighter, cheaper radio wave device could transform telecommunications

That is fairly interesting. The three ports are connected in a ring with three varactor-based parametric resonators which are pumped 120° out of phase. The original paper is in Nature Physics (abstract). I would guess it was anyway as note-worthy as the op-amp 'active circulator' which still gets a mention here. --catslash (talk) 01:58, 12 November 2014 (UTC)

After 3 years; was it used, or what were the problems ? - Rod57 (talk) 11:10, 30 November 2017 (UTC)

Topological insulator used to make miniature microwave circulator.

[1]

In a paper in the journal Nature Communications, researchers led by David Reilly, director of the Microsoft Quantum Laboratory at Sydney Uni, demonstrate how topological insulating materials can be manipulated to produce a miniaturised version of an electronic engineering component called a microwave circulator. Perhaps someone who understands the subject could incorporate this innovation into the article.Rdmoore6 (talk) 17:01, 29 November 2017 (UTC)

I was going to make the same request, as not sure which section it logically fits in. - Rod57 (talk) 11:08, 30 November 2017 (UTC)

What techniques can be used for different frequency ranges

eg different radio/radar/microwave bands. Terahertz ? Relate to optical circulator, goes down to far-IR ? Presumably its just 3 diodes for DC. Could mention typical insertion losses and cross-talk ? - Rod57 (talk) 11:20, 30 November 2017 (UTC)

Second Paragraph of "Ferrite" Section

This paragraph needs work. As written, it is ambiguous at best and misleading at worst. I thought I'd comment on the content first, before making major edits:

1. "Junction type stripline circulators utilize two ferrite disks above and below the stripline." This is quite ambiguous. The stripline circulator is essentially a stripline center conductor sandwich on ferrite, between ground planes. That is, there is one ferrite disk above the stripline circuit and one ferrite disk below the stripline circuit. Perhaps a drawing or picture would clarify this. Stripline circulaotrs do not have to be constructed with disk-shaped ferrites, The ferrites could have most any shape.

2. "These ferrites are circularly magnetized in opposite directions." I don't see how this could be true. The static magnetic bias field is not circular and is through the disk thickness. Both disks are in the same static ad RF magnetic fields.

3. "They form two separate resonators with the stripline disk between them." No, the ferrite disks are not resonators in a stripline circulator. Part of the stripline circuit, which is typically made from sheet metal, is the resonator. The resonator of the stripline circuit is not necessarily a disk, many different geometries are possible. All that is required is that the resonator have three-way symmetry.

4. "The static magnetic bias alters the effective permeabilities in the top and bottom ferrites." Yes, OK.

5. "The ferrite whose circular magnetization is in the same direction as the resultant electron spin precession, will see a permeability increase. The ferrite that is magnetized opposite the electron spin precession will see a permeability decrease." The RF and static magnetic fields are the same in both ferrites. The resonator has two resonant frequencies, known as the split frequencies. The operating frequency is set between the two resonances.

6. "These changing permeabilities result in resonant frequency shifts of the two resonators previously mentioned." There is only one resonator and the permeabilities are static.

7. "The operating frequency is set between the two resonances such that the impedance angle of both resonators is set to 30 degrees (for a three port implementation). The ferrite with the higher permeability will have a higher resonance frequency and an inductive reactance component. The lower permeability ferrite has a lower resonance and capacitive reactance component." These statements seem to be partly based on misinterpretation of the Fay and Comstock paper. I am not sure what is meant by "impedance angle." Both ferrites have tensor permeability that varies with signal propagation direction.

Dlinkhart (talk) 15:55, 8 May 2022 (UTC)

The whole article needs a lot of work; please do make a start on it if you have the enthusiasm. Ideally, there should be a section for each sort of circulator, including lumped-element ('isoductor') circulators which do not even get a mention at present. Also, there is perhaps undue importance given to 'active circulators', placing them on a par with passive circulators as a whole. This was the work of a single editor a few years back. catslash (talk) 19:14, 8 May 2022 (UTC)

A separate article for Active Circulator has been created and I added a link to Active Circulator on the Circulator (disambiguation) page as well. While I was waiting for Wikipedia to create the Active Circulator article, sections on Acoustic Circulators and Optical Circulators were added to this (passive RF/microwave Circulator) article! See separate "talk" on these sections. Dlinkhart (talk) 15:44, 31 August 2023 (UTC)

Acoustic Circulators?

Acoustic circulators are interesting from a physics perspective, but they are for longitudinal pressure waves in fluids, and are *not* RF/microwave devices. Information about them doesn't belong in this article, which is about passive RF/microwave circulators. I have deleted the section on Acoustic Circulators from this article. If there is interest, I will create a new article about Acoustic Circulators that interested parties can expand and edit. Dlinkhart (talk) 15:23, 31 August 2023 (UTC)

I created a new article about Acoustic circulators. These circulators are for airborne sound waves, which makes them entirely different from RF/microwave electromagnetic circulators, so a separate article was needed. Dlinkhart (talk) 17:27, 24 October 2023 (UTC)

Active ("Non-Ferrite") Circulators

There is now an Active Circulator article. Information regarding these circulators should be primarily in the main Active Circulator article, and only briefly mentioned in this (passive circulator) article. Dlinkhart (talk) 17:46, 31 August 2023 (UTC)

Optical Circulators

There is an Optical circulator article. Information regarding these circulators should be primarily in the main Optical circulator article, and only briefly mentioned in this (RF/microwave circulator) article. Dlinkhart (talk) 17:50, 31 August 2023 (UTC)

I moved the content about Optical circulators to the Optical circulator article. Dlinkhart (talk) 17:52, 24 October 2023 (UTC)

Article structure: Types

There is now ample material on conventional microwave circulators, and exotic circulator types now have their own pages. The current structure of the article, dividing Types into Ferrite and Non-ferrite lends undue significance to the latter. Therefore I would favour removing the ferrite/nonferrite level of the section hierarchy, promoting the various types to directly within Types, and moving Theory of operation to the same level (and placed above) Types. The only reason for not immediately doing this myself, is to defer to Dlinkhart, who has done all the work in bringing the article to a good state. catslash (talk) 23:16, 21 November 2023 (UTC)

Thanks! I agree with your proposed structural changes. Some of the present "non-ferrite" section could be rolled into the "Active circulator" article, which I plan to work on, although it's not a high priority. Active circulators can be useful for some applications, but they are by no means a replacement technology for ferrite devices. Dlinkhart (talk) 01:24, 22 November 2023 (UTC)

Done. catslash (talk) 23:28, 18 January 2024 (UTC)