Motorized offset dish by Rotating the LNB inside a fixed sphere

al_madhi

al_madhi

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My Location
Riyadh - Saudi Arabia
#1
Hi , ppl from the plane geometry offset antenna sections cut from larger circular parabolic antenna the same way as sphere shape . Therefore if you look at the attached file you will see what I am planning to design , which is a motorized offset dish , but not by the conventional way , rotating the dish but rotating the LNB instead of the dish , and making the dish is fixed .

The LNB is fastened by two shaft drives , one rotated horizontall and the other one rotates vertically . The sphere's diameter is 180 cm, 240 cm or 360 cm , and its surface is made of thin plastic do that the electromagnetic waves can penetrate without obstruction . , The inside surface of the sphere is painted like mirror paint . By doing so the sun rays cannot penetrate inside the sphere to burn the LNB .

Rotating the LNB inside the spherical mirror the LNB is scanning the surface of the sphere in a such a way selecting different sections , i.e. different offset dishes facing different satellites , similar if you are rotating one offset dish across the Clarke belt from East to West .

Please give your comments whether it can be done or not .



Best Regards
 

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johnsattuk

johnsattuk

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My Satellite Setup
Topfield 5800 Echostar3000,DB7000, Relook 400S, Humax HDC2000, 55cm Fibo Gregorian dish with waveguide and Motek 2100 mod, 90cm Fibo Gregorian dish, 120cm Fibo Gregorian dish on a 1224 motor with waveguide
My Location
West Mids, UK
#2
Hi
I love to see a bit of lateral thinking :D

My maths is a bit rusty, but I dont think a parabola is spherical

What about LNB skew, or rather lack of it, perhaps one inclined motor as for HH mounts would do that

Would look quite nice on the lawn, but is going to take up a lot of room

Wind forces woud be high and it would be difficult to anchor a thin plastic balloon

Haven't quite worked out the advantages yet :(

Keep up the good work, and lets have some pics of the prototype

John
 
S

steffo78

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28E 19E on 120cm Gibertini homemade sidemount with Gibertini feedhorn, Inverto C120. 5E 1W on 85cm triax. Digiality VC-CI 204 and Triax dvb-65s receivers. Matrix-cam not working. Swedish Canaldigital "local", Norwegian Viasat.
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Sweden/Norway,Telemark
#3
A sphere has its focus on 1/2 radius but it is not really focused there so you lose some gain. I dont know how much worse it is compared to a parabola.
I have seen antennas with sphere-design horizontal and parabolic vertikal, I think it is called Torus and were made by SMW, but it is not effecient compared to size.
 
Sir Bronking

Sir Bronking

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medion
pentium4 3.2ghz
progdvb
skystar2 rev2.3
1mtr dish & jaeger 99G 36v motor, with a superjack DP-6600. dvb-t aswell,in the process of setting up
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cheshire,algeria
#4
even if it worked how big would the sphere be :)
 

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Yeshi

Yeshi

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Dm500, TM9100, Samsung V+, 1M Dish. Motect 2100..
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Behind pin 9 on an atmel
#5
Good idea,

Would this mean just put a stick in the ground, hover a Scalextrix around the top with an LNB. and then put a big beach ball around it?

No seriously i doubt it would work, the "Dish part would have to move at some point. unlike fixed shpere the signal is concentrated on the one area etc. But but a motorised LNB version would not only need to be F&@% Off but to get all satellites in wouldnt it have to be flat? and if its flat wouldnt it not be spheric? The signal would just bounce everywhere making the signal shyte.
 
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