Talk:Radiation efficiency

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Attribution[edit]

@Interferometrist: Your edit summary that created this page said "Rescued material from 2 years ago under a page with this title that was then changed to a different (and much less used) subject". Do you recall where you copied that from? See Template:Copied. – wbm1058 (talk) 00:10, 31 July 2020 (UTC)[reply]

Hi. A fair question but difficult for me to answer. I went to look, but because of the fact that deleted pages completely disappear from Wikipedia, I cannot track exactly what happened. From my (poor) memory, there was a page called "antenna efficiency" which actually was meaning aperture efficiency (see section 3) which also now has its own page called Antenna aperture. But what I think is that for some reason I had to delete an old page and create a new one properly called "antenna efficiency" and took the content from the old page before deleting it which is why you can't find it anywhere. Or SOMETHING like that! So I believe you're asking about a page once called antenna efficiency which was eventually deleted, and I believe the only way to look at deleted pages is with the help of an administrator.

So I can't help with your exact question, but if there's some content in particular at issue, please do ask me (and other page watchers) and I will address it. Interferometrist (talk) 14:47, 31 July 2020 (UTC)[reply]

New section?[edit]

@Interferometrist: Hello. I see that you created the "Antenna efficiency" page, some years ago. I have a question about the short paragraph that I wrote yesterday ("In the case of an antenna array having multiple ports... for all possible excitations"). I wonder if you think that this text belongs to a separate section, for instance ==Radiation efficiency of a multiport antenna array==.Evemens (talk) 13:10, 27 February 2022 (UTC)[reply]

@Evemens: Hi, it wouldn't hurt to put a title above the paragraph to set it off, as a special case, but it also looks alright as an appropriate thing to mention in the definition section as it affects the quantification of the term in a particular case. But I DO have a couple questions about the content, without having looked into the references:

Does the reference to mobile phones really have to do with phones themselves having multiple antennas (diversity reception and steered transmission)? Or is this not actually a reference to the towers, where indeed electronically steered arrays are used to "point" their antenna toward each mobile phone in turn?

Secondly, shouldn't there be a specific reference to steered arrays as opposed to antenna arrays in general? In the case of an array antenna being fed by a fixed passive splitting network (which would apply to a lot of cases, depending on whether you wanted to consider the network just part of the antenna or a separate device connected to N ports, which becomes a rather arbitrary distinction) then I don't think this paragraph applies at all (nor does it claim to), because the calculation of electrical efficiency takes the whole system into account and you wind up with one number. But I can easily see that when you change the phases going into separate elements you change the impedance seen (if there are near-field interactions) and amount of power radiated relative to current in each element and losses, so this statement becomes true, so I think it should say right off that it is those sort of arrays you are discussing (I guess it does by saying "multiport" but that wasn't so obvious on a first read). And the calculation of efficiency when a passive network divides the transmitter power in some phase relation, as a function of that pointing, is clear. But what about each element being fed by a separate transmitter (as I believe mobile phone towers do). Then do you not have a separate efficiency for each array element, a different amount of ohmic losses in each element due to its near-field interactions? Now the definition is getting messy, I'd say! Interferometrist (talk) 15:55, 27 February 2022 (UTC)[reply]

@Interferometrist: Hello. During workdays, I am designing antenna systems for my employer, I have no time for Wikipedia. Today (Saturday) I can reply to your comments of last Sunday. First of all, my sentence "These interactions may be large in many actual configurations, for instance in an antenna array built in a mobile phone to provide spatial diversity and/or spatial multiplexing" is accurate and correct. Taking care of this problem is a good part of my current job. For instance, a user equipment (UE) complying with Release 15 of the 5G/NR standards can transmit using 2 antennas simultaneously in the same frequency band, to provide uplink (UL) spatial diversity and/or spatial multiplexing. In these UL-MIMO schemes, the different antennas send different signals, so that there is a separate rf power amplifier to drive each antenna of the antenna array. In ETSI TS 138 101-1 V15.2.0 (a specification of release 15) these UL-MIMO schemes were specified for the NR bands n41, n77, n78 and n79. ETSI TS 138 101-1 V15.2.0 was released in 2018, this is not the latest specs. In addition, for the downlink (DL), that is reception by the UE, the same standard requires the UE to be equipped with a minimum of 4 RX antenna ports for the NR bands n7, n38, n41, n77, n78 and n79. This means a minimum of 4 antennas, each connected to a separate receiver to receive separate signals. More recent releases increase the requirements for MIMO UL and DL.

Regarding your other comments ("Secondly, shouldn't there be a specific reference to steered arrays..."), I have changed the previous reference ^[1] (an excellent book) for a more appropriate one ^[2]. The book ^[2] is older, but chapter 10 of this book, titled "Multiple antenna terminal" is very relevant to what I wrote. I think that together with the Broyde et al article, which covers the computation of the radiation efficiency in all possible cases, it fully covers your comments. This recent article was brought to my attention some weeks ago by Helloch in a contribution to the Antenna array page.

Finally, note that, following your advice, I have put a small title above the paragraph, to set it off as a special case. Evemens (talk) 10:12, 5 March 2022 (UTC)[reply]

References

^ Clerckx, Bruno; Oestges, Claude (2013). MIMO Wireless Networks, 2nd edition. Elsevier. ISBN 978-0-12-385055-3.
^ ^a ^b Sibille, Alain; Oestges, Claude; Zanella, Alberto (2011). MIMO: From Theory to Implementation. Elsevier. ISBN 978-0-12-382194-2.

Measurements[edit]

@Interferometrist: If I understand correctly, you wrote "For other types of antenna the radiation efficiency is less easy to calculate and is usually determined by measurements." I think this statement should be modified, because measurements of radiation efficiency are very difficult. The old "Wheeler cap" method is quite inaccurate, and therefore only useful for antennas having a low efficiency. Today, the practical methods are based either on a multi-probe antenna pattern measurement system, or on mode-stirred chamber techniques. Both approaches are expensive and complex, and available only for physically small antennas. Also, I am not aware of any radiation efficiency measurement technique that can take ground loss into account. Evemens (talk) 10:24, 5 March 2022 (UTC)[reply]

@Evemens: Hello. I edited your "Measurement of the radiation efficiency" section, to add the important pattern integration method, and a reference to IEEE Std 149. FreddyOfMaule (talk) 13:20, 19 November 2022 (UTC)[reply]

Thanks.Evemens (talk) 10:44, 26 November 2022 (UTC)[reply]

[1] Clerckx, Bruno; Oestges, Claude (2013). MIMO Wireless Networks, 2nd edition. Elsevier. ISBN 978-0-12-385055-3.

[Sibille-2] Sibille, Alain; Oestges, Claude; Zanella, Alberto (2011). MIMO: From Theory to Implementation. Elsevier. ISBN 978-0-12-382194-2.

[1]

[2]