I know the screw applies for C Band.
I know the screw does not matter for Ku circular, e.g. Dish and DTV
* Does the scew apply for FTA Ku linear, also for Shaw Direct?
Thanks
Vixens,
Just to elaborate (since your question has already been anwered). Here is a way to visualize what skew means for a LINEAR sateliite transmission...
Picture a big old rainbow in the sky, this one hanging from the east to the west and to your south if in the northern hemisphere or to your north if you are in the southern hemisphere.
Everyone has seen a rainbow, so it is a simple analogy to use here. This imaginary rainbow simulates the Clarke Belt where the geostationary communication satellites reside.
Picture that rainbow with + signs staggered all across it. The + signs are the satellites and each + sign must have the vertical bar "|" perpendicular to the arc of the rainbow and the horizontal bar, the "--", tangent to the rainbows arc.
If you were to look due south at one of these "+" signs on the rainbow, it would appear to be perfectly vertical and level. No skew is required here. But, think about looking to the western end of the rainbow or the eastern end. The "+" sign has to lean to the one side on the west and the opposite sid on the east - from YOUR point of view or from your geographic location. Regardless of which hemisphere you are in, if the arc leans to the east, the satellite "appears" to lean to the east. If the arc leans to the west, the satellite "appears" to lean to the west.
Your linear LNBF has two probes fixed inside at the bottom of the waveguide throat which are set in a "+" sign arrangement. These pickup probes must align to the satellite's "+" antenna array layout to capture the maximum signal. So, you must tilt or "skew" your LNBF to match the perceived angle of the satellite in the sky. So rotate the LNBF so that the top of it follows the direction of the arc of the imaginary rainbow to align the "+" signs or the polarity. If the satellite is to your right, lean the "+" sign to the right or rotate the LNBF to the right (remember to think of this when standing BEHIND the dish and not in front of it). Or, think of it as you would if you were aiming a rifle with a scope and crosshairs. Tilt the crosshairs to the direction of the arc. You would be standing BEHIND the rifle (I certainly hope). A little humor there.
I must point out that if you are rotating one LNBF to align the polarity, it is referred to as "POLARIZATION", not "SKEW". Skew comes into play when you have multiple LNBFs on ONE eliptical dish. Here, you may have to twist the dish's reflector so that all the individual satellite signals bounce off the reflector dish and converge on their one intended target, which is JUST ONE of the multiple LNBFs attached out on the arm. So, multiple LNBFs - adjust the SKEW of the DISH. ONE LNBF - adjust the POLARITY or rotation of the LNBF.
RADAR
