This comes from another thread:

Add to this that even if you've got a DirecTV dish perfectly aimed at 119 and 101, you'll have to mess with the elevation of 99 and 103 to get the most signal. My question is why?

For a satellite to be in geosynchronous orbit, it has to have a period of rotation identical to that of the earth and it has to be positioned directly above "the equator." Now, this "equator" might not be exactly above the equator at sea level, but the satellite has to be directly above it.

What would happen if the satellite were not directly above the equator? As the earth rotates, the satellite would sometimes appear slightly higher than other times. It would spend exactly the same amount of time above the equator as below it, and it would go just as far above as below. That means it would be stationary as far as azimuth, but not elevation.

So how can it be that some satellites are higher than others? If you have satellites not close to one another, such as 101 and 119, and the LNB arm was not at the correct tilt. Correcting that tilt should place ALL the satellites in a line.

Yet, still, the elevation of the satellites is not the same.

Simple...

The earth is flat.

There are no satellites as there are really super high antennas. Dish TV could only afford a 4 mile high antenna, where DirecTV could afford a 5 mile high. Hence the difference of elevation of the “satellite” dish.

The earth does not rotate, rather the sun and moon rotate around the earth.

KOT

Brilliant.

KOT, I'm not talking about the elevation of DirecTV satellites compared to Dish Network satellites. I'm talking about different DirecTV satellites "near" one another (99, 103) that peak out at different elevations on the same dish.

There can be different elevation differences between different dishes as it's possible to build the dishes in such a way that the signal focuses at a different height off the dish. That's not what I'm talking about.

Why, thank you!

Getting back to the satellites, I've just looked at Dishpointer info, and the 99 (99.1), 101, and 103 (102.8) satellites would NOT require different elevation settings if used with a dish set to the proper tilt. So, I don't know... I've seen this, for sure!

[Link: en.wikipedia.org]

Brad,
Thank you for that wiki reference. In that you'll find that "geostationary orbits have an inclination of 0° with respect to the Equator," which is exactly what I said. If they are all at that inclination (elevation as we see them from here), how is it possible that we can peak the signal from one satellite, say 101, then find that we have to raise or lower the elevation of the dish to peak an adjacent satellite?

You're not AT the equator, where the inclination may be 0 degrees but at 35-48 degrees latitude, any difference in the satellite's altitude will show up when setting up the dish, which is NOT aimed directly at the bird, like a C-band dish is. The non-spherical shape and asymmetry of the LNB are their attempt at dealing with the differences. You can't peak it for one and have the best performance from another- you need to find a happy medium.

At least they aren't using balloons to suspend the repeaters.

And how would the Sun & Moon orbiting the Earth account for gravity?

I'm actually asking a serious question. For some of you:

It Is Better to Remain Silent and Be Thought a Fool than to Speak and Remove All Doubt.

This is variously attributed to Abraham Lincoln, Mark Twain, Biblical Proverb, Maurice Switzer, Arthur Burns, John Maynard Keynes, Confucius, and the terribly prolific writer Anonymous.

My first post WAS serious, having previous experience with C-band. If you didn’t consider the geometric aspects of your question, that’s not our problem.

Well, in that case, I don't agree with you.

The DirecTV dishes differ from C-Band dishes in two important ways:

Both types are based on a parabolic reflector, but the DirecTV dish doesn't cut a circle around the LNB arm but instead shifts the dish cut off of the center so that the arm is not in front of the dish; and

It's not simply a parabola, since it's made to gather enough usable signal from more than one azimuth direction. It's a widened modification of a parabola, extending the aiming abilities laterally along the ecliptic.

Neither of those differences explain why satellites close to one another would be peaked at different elevations. A parallel case for a C-Band antenna would be for you to point a perfectly installed and pointed antenna at the correct azimuth, then find that you have to change the elevation to peak one or more satellites.