& 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. Thanks Graeme On Fri, 26 Oct 2018 at 07:45, Kevin Kenny <kevin.b.ke...@gmail.com> wrote: > On Thu, Oct 25, 2018 at 4:46 PM Warin <61sundow...@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@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging >
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