[Tagging] Radio telescopes
graemefitz1 at gmail.com
Thu Oct 25 22:44:30 UTC 2018
& 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
On Fri, 26 Oct 2018 at 07:45, Kevin Kenny <kevin.b.kenny at gmail.com> wrote:
> On Thu, Oct 25, 2018 at 4:46 PM Warin <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. 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!"
> Tagging mailing list
> Tagging at openstreetmap.org
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Tagging