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Repoposing Sky dishes?



 
 
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  #21  
Old March 18th 19, 03:57 PM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Default Repoposing Sky dishes?

On Monday, 18 March 2019 08:53:22 UTC, Brian Gaff wrote:
Yes some of these magic heat retentive coatings its a lot more, apparently.
The thing is it worries me that for the want of a few pence they could
easily add a socket to a router so an extra aerial could be added outside.
Brian

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On 17/03/2019 11:13, Indy Jess John wrote:
On 17/03/2019 09:37, Terry Casey wrote:

Another suggestion, as it is just across the road, is to use a
wifi router with a traditional whip aerial and make a suitable
reflector to direct all the energy in one direction.

I have seen it done with the sending end positioning the router so that
its broadcast includes an upstairs window looking towards the receiving
point opposite, and in the upstairs window of the receiving point
opposite is a wifi repeater which re-broadcasts to the rest of that
house. It works because the upstairs windows are above the normal traffic
height, but I suppose if the sending end had thought to use a reflector
it would work better.

Next time I am round that way I might mention trying a reflector.

Jim


I tested loss through my double glazing and at 2.4GHz it was 9dB.

Bill


Many homes now have either insulation boards with aluminium foil coating in the walls or have been injected with aluminium coated polystyrene beads.

The former make a pretty effective Faraday cage...
  #22  
Old March 18th 19, 03:59 PM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Posts: 826
Default Repoposing Sky dishes?

On Sunday, 17 March 2019 22:04:52 UTC, Vir Campestris wrote:
On 17/03/2019 21:53, Dave W wrote:
Sky dishes work with satellite frequencies far above the 2.4MHz of
wifi. What you need is a yagi array dimensioned for wifi, pointing at
the target. One of the people in my first job in a TV lab did this
with a standard UHF aerial to transmit down to the other end of the
long lab. UHF TV starts at about 500MHz so an aerial for 2.4MHz would
be 200 times bigger. Forget my first suggestion!


WiFi is 2.4GHz, not MHz. Or 5GHz.

Andy


Indeed - Yagi's for 2G4Hz are widely sold. Not seen many (or dishes for that matter) for 5GHz, however the dishes for C Band satellite TV (~4GHz) are pretty large typically 1.5m+
  #23  
Old March 18th 19, 04:06 PM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Default Repoposing Sky dishes?

On Monday, 18 March 2019 04:02:35 UTC, wrote:
On 17/03/2019 08:06, Brian Gaff wrote:
? Somebody asked me if it might be possible to use to old sky dishes to
shove wifi signals over the road. I would not actually know, but I'd imagine
the problem part would be to have a recieve and transmit aerial in the focal
point and with the same polarisation myself.


The wavelength of 2.4GHz wifi is 125mm. A mini dish is 400mm across. A
dish only 3.2 wavelengths across would have no focusing ability whatsoever.

If you wish to fatally irradiate the people across the road by putting a
microwave oven magnetron at the focal point of a dish you would need a
dish at least 3 metres diameter.

Bill


I see.

How are your death ray experiments getting on Bill?

In reality even if the entire output of a 1kW magnetron could be focused into a single person, it would take quite some time for them to die of heatstroke, and they might notice they were getting hot.

OTOH here are a couple of comedians who conducted animal experiments on the concept:-

https://youtu.be/8uAVp60X_p0
  #24  
Old March 18th 19, 06:57 PM posted to uk.tech.digital-tv
Richard Tobin
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Posts: 1,351
Default Repoposing Sky dishes?

In article ,
R. Mark Clayton wrote:

In reality even if the entire output of a 1kW magnetron could be focused
into a single person, it would take quite some time for them to die of
heatstroke, and they might notice they were getting hot.


Presumably it would be not unlike sitting in front of a 1-bar electric
fire...

-- Richard
  #25  
Old March 18th 19, 08:08 PM posted to uk.tech.digital-tv
Terry Casey[_2_]
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Posts: 965
Default Repoposing Sky dishes?

In article , briang1
@blueyonder.co.uk says...

Yes some of these magic heat retentive coatings its a lot more, apparently.
The thing is it worries me that for the want of a few pence they could
easily add a socket to a router so an extra aerial could be added outside.


Brian, my first Netgear router had the whip plugged into the
back although what the connector was and how easy it would be
to buy another pair, I have no idea.

It probably ended up in a box when we moved - it will probably
resurface one day!

--

Terry

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  #26  
Old March 18th 19, 08:18 PM posted to uk.tech.digital-tv
Terry Casey[_2_]
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Posts: 965
Default Repoposing Sky dishes?

In article -
september.org, lid says...

One I saw - and might be possible to find with a web search -
used card covered with tinfoil used to form a reflector in the
form of a V and showed how to cut and fold the card so that it
had a base with a hole in it so that it simply fitted over the
whip and automatically placed the reflector at the optimum
distance away.


Found it!

http://freeantennas.com/projects/Ez-10/index.html

Here's a more impressive looking affair but whether it has any
advantages other tha physical strength, I have no idea (I
haven't actually watched it).

https://www.youtube.com/watch?v=fw6xkJXXJaA

--

Terry

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  #27  
Old March 18th 19, 08:56 PM posted to uk.tech.digital-tv
Java Jive[_3_]
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Posts: 1,892
Default Repoposing Sky dishes?

On 18/03/2019 17:57, Richard Tobin wrote:

In article ,
R. Mark Clayton wrote:

In reality even if the entire output of a 1kW magnetron could be focused
into a single person, it would take quite some time for them to die of
heatstroke, and they might notice they were getting hot.


Presumably it would be not unlike sitting in front of a 1-bar electric
fire...


IANA medic or microwave expert, but I don't think so. AIUI, the idea of
cooking by microwave is that the waves penetrate some distance into the
food before imparting their energy, usually into water molecules within
the food. By contrast the electric fire would only warm your skin.

But perhaps Jim LeSurf will be along in a while to put me right?!

  #28  
Old March 18th 19, 09:05 PM posted to uk.tech.digital-tv
Richard Tobin
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Posts: 1,351
Default Repoposing Sky dishes?

In article ,
Java Jive wrote:

In reality even if the entire output of a 1kW magnetron could be focused
into a single person, it would take quite some time for them to die of
heatstroke, and they might notice they were getting hot.


Presumably it would be not unlike sitting in front of a 1-bar electric
fire...


IANA medic or microwave expert, but I don't think so. AIUI, the idea of
cooking by microwave is that the waves penetrate some distance into the
food before imparting their energy, usually into water molecules within
the food. By contrast the electric fire would only warm your skin.


It's true that they penetrate some way in - of the order of a
centimetre for meat. But they impart energy over that centimetre, not
after it. So I'm not sure how different it would feel.

-- Richard

  #29  
Old March 19th 19, 12:48 AM posted to uk.tech.digital-tv
tony sayer
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Posts: 4,132
Default Repoposing Sky dishes?

In article , Java Jive
scribeth thus
On 18/03/2019 17:57, Richard Tobin wrote:

In article ,
R. Mark Clayton wrote:

In reality even if the entire output of a 1kW magnetron could be focused
into a single person, it would take quite some time for them to die of
heatstroke, and they might notice they were getting hot.


Presumably it would be not unlike sitting in front of a 1-bar electric
fire...


IANA medic or microwave expert, but I don't think so. AIUI, the idea of
cooking by microwave is that the waves penetrate some distance into the
food before imparting their energy, usually into water molecules within
the food. By contrast the electric fire would only warm your skin.

But perhaps Jim LeSurf will be along in a while to put me right?!


JOOI where is our Jim, haven't seen him post for a while anywhere now?..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.


  #30  
Old March 19th 19, 04:34 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,601
Default Repoposing Sky dishes?

On 18/03/2019 15:06, R. Mark Clayton wrote:

If you wish to fatally irradiate the people across the road by putting a
microwave oven magnetron at the focal point of a dish you would need a
dish at least 3 metres diameter.

Bill


I see.

How are your death ray experiments getting on Bill?


I've run out of neighbours.

Bill
 




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