[Tagging] Radio telescopes

Warin 61sundowner at gmail.com
Fri Oct 26 02:21:49 UTC 2018


On 26/10/18 09:44, Graeme Fitzpatrick wrote:
> & to throw another spanner in the works :-), what do you call 
> satellite dishes, either bubby ones for home use 
> https://goo.gl/images/qaDzSX or big commercial versions 
> https://goo.gl/images/44ZhNd?
>
> They're certainly not towers, but they definitely are for 
> communication purposes.

Err the first one could be for reception only, so not communication.
They usually receive TV signals. They are fairly frequent in remote 
areas, and with ex-pats who want to look at their home TV stations.

There is little to distinguish between the reception only and two way 
communication types.

>
> Thanks
>
> Graeme
>
>
> On Fri, 26 Oct 2018 at 07:45, Kevin Kenny <kevin.b.kenny at gmail.com 
> <mailto:kevin.b.kenny at gmail.com>> wrote:
>
>     On Thu, Oct 25, 2018 at 4:46 PM Warin <61sundowner at gmail.com
>     <mailto:61sundowner at gmail.com>> wrote:
>
>         On 25/10/18 23:56, Paul Allen wrote:
>>         BTW, these days few radio telescopes are dishes.  Most of
>>         them are phased arrays and not on towers
>>         or masts.
>
>         That depends on the frequency of operation.
>
>         New dish reflecting ones are being build. They simply perform
>         the best for the intended frequencies.
>
>
>     And there are dishes with phased arrays at the feed point, for
>     beam forming, and phased arrays of dishes, for long-baseline
>     interferometry.  It all depends on what frequency, SNR,
>     polarization and angular resolution you need. Paul is right that
>     larger phased arrays are now practicable because of better
>     electronics, giving dishes less of an advantage, but phased arrays
>     are as old as radio astronomy.
>


Arrays of  dishes are being used too, over very large distances. But 
they can also be used individually, so each one needs to be tagged as a 
separate antenna.
Where it is known that they are in some way combined for use then 
perhaps a relation could be used to signify this.

See Way: Murchison Widefield Array (607964749)
   Tags:
     "antenna"="2048 dual-polarization dipoles"
     "area"="yes"
     "website"="http://www.mwatelescope.org/"
     "man_made"="radio_telescope"
     "name"="Murchison Widefield Array"
     "description"="when combined from each antenna forms a single 
telescope"
     "frequency"="80 - 300 MHz"

This encompasses the area, but does not link the individual antennas  
nor any other infrastructure. Maybe a site relation could be used.


>     Jansky built his "merry-go-round" Bruce antenna (20.5 MHz) in
>     1932, while Reber didn't build his first dish until 1937. Jocelyn
>     Bell discovered pulsars on a phased array built at Cambridge by
>     Ryle and Hewish (which also produced the 3C catalog of radio
>     sources - including 3C273, the first known quasar).
>
>     The conclusion is either, "Life is full of tradeoffs," or "you
>     really don't want to know!"
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