I'm in a creative mood...

[2cvbloke]

Aswell as turning an old Nokia 780IRD into a Mini-ITX PC and respraying my Nokia 9800S silver (so it looks like the 9902S PVR), I thought about having a go at making a Gregorian dish using my porty dish and a bigger dish than I have (1-1.2M maybe)...

So, what dish size would the porty dish be a good sub-reflector on?

And yes, I do know it takes precise calculations and stuff to make a greg in a factory, but I'm bored!!!

 

[Park Royal]

Does not the sub reflector have to be circular? ie a small parabola, not part of an offset parabola. Might be wrong but that is how I see them.
PR

 

[2cvbloke]

Does not the sub reflector have to be circular? ie a small parabola, not part of an offset parabola. Might be wrong but that is how I see them.
PR

Might be, but I'm just playing about, but wouldn't mind a bigger dish to play with though (after I make a home-made Greg)...

 

[Skip Channel]

I was messing about with my Porty dish at my parents' place a couple of months ago and was trying to get 13e through an open window. The dish had to be pointing at 13e or to west of 13e. I somehow managed to get a couple of transponders on 28e. I was amazed when I did the TP scan and saw BBC 1 (or 2) regions!

I would say it was definately the open window bouncing the signal, even if it was scattering it all over the place. On these two (maybe more) frequencies it just happened to be scattering enough of the signal towards the Porty dish.

Opening the window further (whilst not moving the dish anywhere) meant the signals disappeared - even though that meant the dish had far less window obscuring it.

 

[2cvbloke]

I was messing about with my Porty dish at my parents' place a couple of months ago and was trying to get 13e through an open window. The dish had to be pointing at 13e or to west of 13e. I somehow managed to get a couple of transponders on 28e. I was amazed when I did the TP scan and saw BBC 1 (or 2) regions!

I would say it was definately the open window bouncing the signal, even if it was scattering it all over the place. On these two (maybe more) frequencies it just happened to be scattering enough of the signal towards the Porty dish.

Opening the window further (whilst not moving the dish anywhere) meant the signals disappeared - even though that meant the dish had far less window obscuring it.

Sounds like an accidental Luneberg lens effect to me...

But what about making a Gregorian with a Porty dish???

 

[CROSSBONES]

Good luck m8 youll need it

Here`s some figures that might help you.

-http://www.satellite-calculations.com/

 

[2cvbloke]

Well, there's some nice pics, but it doesn't say what size the sub-reflector should be in relation to toe main reflector...