Talk:Directivity

Directivity / Directive Gain

This article confuses directivity and directive gain. The function of direction is usually called the directive gain, and the peak directive gain (or the directive gain in the direction of interest) is called the directivity (see for example Orfanidis [1] and the IEEE dictionary^[1]).

--catslash 18:04, 31 August 2007 (UTC)[reply]

OK - I stand (semi-) corrected; later editions of the IEEE dictionary (including the 6th ed. ^[1]) say that the term directive gain is now deprecated and that directivity should be used both for a given direction and for the maximum (If the direction is not specified, the direction of maximum radiation intensity is implied). However, I'd say that it's still common practice to distinguish the two terms (as in Orfanidis [2]). --catslash 10:06, 4 September 2007 (UTC)[reply]

Things to Add

Here're some things that the article could mention:

Reciprocity: The directivity is equally relevant to receiving antennas - also mention Friis transmission equation / link budget?
Partial directivity / partial directive gain (definition of).
Gain: The definition given here agrees with the IEEE definition^[1] (so perhaps it should refer to radiation efficiency rather than the antenna efficiency). Nevertheless it's fairly common to define the gain so as to include the loss due to reflection at the antenna feed point (i.e. due to mismatch between the feed-line and antenna impedances) - and this ought to be be mentioned. See Balanis ^[2] who switches definitions between editions.

--catslash 18:04, 31 August 2007 (UTC) Note regarding the gain: the IEEE Dictionary^[1] calls this quantity the realized gain; so[reply]

{\begin{aligned}G_{realized}&=e_{match}G\\&=e_{match}e_{rad}D\\&=e_{antenna}D\end{aligned}}

e_{match}={\frac {P_{acc}}{P_{feed}}}=1-|s_{11}|^{2}

e_{rad}={\frac {P_{rad}}{P_{acc}}}={\frac {P_{rad}}{P_{rad}+P_{loss}}}

e_{antenna}=e_{match}e_{rad}

where $e_{antenna}$ is the antenna efficiency, $e_{rad}$ the radiation efficiency and $P_{acc}$ is the power 'accepted' by or 'delivered' to the antenna from the feed. --catslash 16:05, 17 September 2007 (UTC)[reply]

References

^ ^a ^b ^c ^d Institute of Electrical and Electronics Engineers , “The IEEE standard dictionary of electrical and electronics terms”; 6th ed. New York, N.Y., Institute of Electrical and Electronics Engineers, c1997. IEEE Std 100-1996. ISBN 1-55937-833-6 [ed. Standards Coordinating Committee 10, Terms and Definitions; Jane Radatz, (chair)]
^ Constantine A. Balanis: “Antenna Theory, Analysis and Design”, John Wiley & Sons, Inc., 2nd ed. 1982 ISBN 0-471-59268-4

dish antennas

there is no discussion of dish antennas, but those are both very important and it is easier to calculate directivity with them. -- 135.23.66.249 (talk) 17:07, 22 July 2017 (UTC)[reply]

External links modified

Hello fellow Wikipedians,

I have just modified one external link on Directivity. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

Added archive https://web.archive.org/web/20070816093646/http://www.rane.com/par-q.html to http://www.rane.com/par-q.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 04:27, 11 September 2017 (UTC)[reply]

[IEEEdict1997-1] Institute of Electrical and Electronics Engineers , “The IEEE standard dictionary of electrical and electronics terms”; 6th ed. New York, N.Y., Institute of Electrical and Electronics Engineers, c1997. IEEE Std 100-1996. ISBN 1-55937-833-6 [ed. Standards Coordinating Committee 10, Terms and Definitions; Jane Radatz, (chair)]

[Balanis-2] Constantine A. Balanis: “Antenna Theory, Analysis and Design”, John Wiley & Sons, Inc., 2nd ed. 1982 ISBN 0-471-59268-4

[1]

[2]