I was on a country lane the other day when I saw what looked like an FTA enthusiast trying to tweak his dish. There was something very odd about this dish, so I leaned over the fence and asked him what kind of dish it was. He invited me into the yard and showed me what looked like a windmill with spokes sticking out of the hub. Each of the individual spokes (or, as he called them, paddles) was like a tapered arm, and these spokes were gently curved towards the sky. The lnb was totally disconnected from the hub and spokes and ran in its own guideway, either closer to the hub or further away.
He told me that it worked on the same principle as a C-Band mesh dish being able to receive higher frequency Ku signals. As long as there is not too much air space between the metal components the signal sees what it thinks is a solid dish. To achieve this effect he started the hub spinning, faster and faster.
With the dish spinning, the paddles became a blur. You could see that, as the speed increased, the tapered, curved arms of the virtual dish started to straighten out. He said that at any given speed, the parabolic shape was retained, but the focus changed in proportion to the speed.
He told me that as the rotational speed went up, the apparent solidity of the dish increased allowing higher frequencies to be tuned in. When you need more focus on the signal, slow down the speed which allows the spokes to curve back towards their resting position making the focal point move inwards. This is where the lnb moved in sympathy in its guide according to the speed of the rotation to match the changing focal point.
He said is was great in a wind since the inertia of the moving parts kept the dish firmly oriented to the satellite and resisted any wind torque on the dish.
Then a little dog ran over towards us trailing a leash behind it. Unfortunately as the dish was spinning it managed to pick up the leash and threw the dog up into the air and over a tree. I know what you are thinking, but let me reassure you, don't worry, everything was okay, we checked and there was no damage to the dish at all and the signal was as strong as ever.
You never have your camera when you really need it.
He told me that it worked on the same principle as a C-Band mesh dish being able to receive higher frequency Ku signals. As long as there is not too much air space between the metal components the signal sees what it thinks is a solid dish. To achieve this effect he started the hub spinning, faster and faster.
With the dish spinning, the paddles became a blur. You could see that, as the speed increased, the tapered, curved arms of the virtual dish started to straighten out. He said that at any given speed, the parabolic shape was retained, but the focus changed in proportion to the speed.
He told me that as the rotational speed went up, the apparent solidity of the dish increased allowing higher frequencies to be tuned in. When you need more focus on the signal, slow down the speed which allows the spokes to curve back towards their resting position making the focal point move inwards. This is where the lnb moved in sympathy in its guide according to the speed of the rotation to match the changing focal point.
He said is was great in a wind since the inertia of the moving parts kept the dish firmly oriented to the satellite and resisted any wind torque on the dish.
Then a little dog ran over towards us trailing a leash behind it. Unfortunately as the dish was spinning it managed to pick up the leash and threw the dog up into the air and over a tree. I know what you are thinking, but let me reassure you, don't worry, everything was okay, we checked and there was no damage to the dish at all and the signal was as strong as ever.
You never have your camera when you really need it.
:up
