2007-01-19 02:02:54 · 9 answers · asked by BOB 1 in Science & Mathematics ➔ Physics
The shape of the dish helps provide the best signal for your viewing pleasure. It's a collector and a reflector.
A dish antenna "picks up" satellite signals that are in the air. These signals travel in waves and are (obviously) not something humans can detect without the help of electronics of some sort.
Despite the commercials for the dish, a satellite in space does not really "beam" a stream of data directly to your antenna. Instead your antenna must gather the slightly more scattered signals. That's why the antenna must have a reasonable sized area (the dish). The area is domed (like an inverted umbrella) so the waves of data gathered will "bounce" off the dish and be reflected towards the focal point of the dome. (This is a mathematical concept; I've never been good at teaching math. Look at the link below for more info about focal points.) The part of your antenna that collects and processes the signals is situated at the focal point. Your data is collected and transferred to your TV so you can watch any of the hundreds of channels your dish is gathering data for.
2007-01-19 02:21:04 · answer #1 · answered by Annie 3 · 0⤊ 0⤋
They're shaped that way so that all of the signals being received can be bounced to the real receiver(sometimes it's another mirror that bounces the signal into the center of the dish), which is the thing that sticks out of the main dish. If you understand concave-curved mirrors, that little thing sticking out is the 'focal point' of the dish. if you don't get it, it's like how when you put a lens of a magnifier, pair of glasses, or contacts up to the sun, sometimes you see a small rainbow in the ground, and it's all at one point. that small point is the focal point of the lens. focal is from focus, so you could think of it as being like that's where all the energy from that curved lens is being focused on. Sorry if it seems like I started going on and on anywhere here, but the point is that the dishes are shaped that way and the real receiver is put at that exact length(but the length depends on the type of dish) so all the incoming signals are reflected off of the dish and to that receiver, which will sometimes just be a 'signal mirror' that bounces everything into a receiver, which will send the signals into the TV or whatever else there is. Hope this helped.
2016-03-18 00:16:25 · answer #2 · answered by Anonymous · 0⤊ 0⤋
It focuses the signal. The shape of the dish is actually a paraboloid, having a cross-section that is a parabola. When a signal enters the dish in a direction parallel to its axis, the geometric properties of the parabola result in the entire signal being reflected to a single point, appropriately called the focus. The receptor of a dish antenna is located at the geometric focus of the parabola.
2007-01-19 02:08:12 · answer #3 · answered by DavidK93 7 · 2⤊ 0⤋
It is not shaped like an umbrella, it is shaped like a parabola.
A parabola is a shape that has the property of focusing waves coming in almost parallel, electro-magnetic waves originating from an infinite or very long way away to one point.
The transducer or sensor is then placed at that point to collect and process the signal.
Think of a solar oven, in this case the waves are IR heat waves from the sun, and the collector is a black box with food to cook inside it. By focusing all the waves on the box the maximum heat energy is delivered to the box to heat it up and cook the food inside.
2007-01-19 02:14:33 · answer #4 · answered by themountainviewguy 4 · 0⤊ 0⤋
It is shaped just as a concave mirror so that the signals are concentrated to the actual place where they are absorbed. Metal reflect the wave just as the polished surface reflects light in a concave mirror.
The dish is not the antenna, the real antenna is at the focal point of the dish shaped metallic concave mirror
2007-01-19 02:08:27 · answer #5 · answered by RMG 3 · 2⤊ 0⤋
It's actually a parabola. It focuses the incoming radio/TV signals to a single point where the actual antenna is. The dish art is just a focusing device.
2007-01-19 02:09:51 · answer #6 · answered by Gene 7 · 0⤊ 0⤋
To focus the incoming signal onto the detector. The incoming waves are reflected by the dish and, because of its shape, they all pass through the same point (called the focus). If you put the detector at this point then the signal will be much larger.
2007-01-19 02:09:17 · answer #7 · answered by Sam G 4 · 1⤊ 0⤋
Would you prefer the shape of an unbrella that is inside out???
2007-01-19 02:13:35 · answer #8 · answered by chazzer 5 · 0⤊ 2⤋
to protect your house against fallin meteors and asteroids falling from the satellites that pres bush put in the outer space
2007-01-19 02:08:49 · answer #9 · answered by A to the T 2 · 0⤊ 3⤋