A satellite antenna dish shape of a paraboloid 10ft across at the open end and 3 ft deep. where is the focus?
547016
This is a 3D problem that can be treated as a 2D problem due to azymuthal symmetry.\nFirst of all recall the general equation for a parabola:\ny-y0 = 4*p (x-x0)^2\nWhere p is the focal lenght.\nNow, if we set the vertex of the parabola (in this case of the parabolic dish) at the origin, x0=0, y0=0.\ny = 4*p x^2\nIn the previous equation susbtitute y=3, x=5.\nThe resulting 'p' will be the focal length measured in feet.
901312
b) is the correct answer, as others have said. You know, telescopes are a lot easier to understand if you look at a diagram.\n\nYou can find some here: http://en.wikipedia.org/wiki/Reflector_telescope
874938
I assume you mean a half-wave dipole antenna.  The formula is L = 468/f, or f = 468/L, where f is the frequency in megahertz and L is the length in feet.  This formula takes into consideration "end effects," ie, deviation of antenna performance from the theoretical ideal, due to charge accumulation at the antenna tips.  For a folded dipole, or other similar antenna that doesn't have open ends, it's f = 492/L.
1004086
A parabola is a shape formed by all the points that are an equal distance from a line, called the directrix, and a point, called the focus. The interesting thing about parabolas is if you have a three-dimensional figure formed by rotating a parabola on its vertex, if you place a light source at the focus, the light that shines back and hits the parabolic surface will be reflected outward in parallel lines, creating a strong beam. This is how flashlights work. Also, if you use a parabolic shape for an antenna, signals coming in from space or whatever will hit the surface of the parabola and all be reflected onto the focus. If you put a receptor there, you will receive a very strong signal. That's a couple real life uses of parabolas.
104230
This shape is called the "omega shape", at least as the lower limb of the sun disappears beneath the apparent horizon (the sun has already set quite a bit farther beneath the horizon and one is only seeing so much of the sun because of refraction effects). It is called an omega because it is not strictly an oval or ellipse at that point, and actually has a pair of "feet" at the bottom like an omega. \n\n The actual shape will vary, depending on refraction effects, and those depend on the temperature profile of the atmospheric layers. The shape is typically computed in a simulation by ray-tracing, although one might be able to do some sort of approximation by an ellipse. See the attached link for more details.
641787
1. Point satelite dish at the right point in the sky.\n\n2. Use a LNB to down-convert the signal to one which can be routed to the reciver using normal coax.\n\n3. Tune the reciever to the correct frequency.\n\nVoila... you have access to the satellite. Bit more info would help... which one, what for etc. :o)
151096
There are two types of satellites: polar and geostationary. Polar satellites circle the earth, covering the north pole and the south pole on every circle, at an altitude of about 850 km. A geostationary satellite "moves with the earth" and is always situated over the same place over the equator, at an altitude of about 36000 km.
671221
The Sputnik 1 satellite was a 58.0 cm-diameter aluminum sphere that carried four whip-like antennas that were 2.4-2.9 m long. The antennas looked like long "whiskers" pointing to one side.\n\nWho plays basketball with a 23 inch diameter ball?
459122
the side length is 2\nso the altitude should be 3^(1/2)\ngood luck
646861
The Yagi-Uda Antenna consists of a minimum of 3 elements, though 6 elements tend to be an optimum configuration.\n\nOne of the elements is called the "driven" element. One of the elements is called the "reflector" and the rest are called the "directors".\n\nThe reason why the reflector is such is wrapped up in transmission line theory. In a nutshell, the reflector is slightly longer than lambda/2 and it acts as an inductor and thereby acts as a reflector.\n\nThe directors are slightly shorter than lambda/2, acting as a capacitor and hence directs the wave.
516761
The largest SINGLE antenna radio telescope is near Arecibo, Puerto Rico. It's diameter is 1000 feet.\n\nThe largest MULTIPLE antenna radio telescope is near Socorro, New Mexico. Its 27 antennas effectively make up an antenna 22 miles in diameter http://www.vla.nrao.edu/
224346
There is such a thing but unfortunately I have no idea what it's called. I do know that 'they' intend to build a satellite tower that reaches into space with it. It was featured in some magazines about two years ago.
353306
Try this site too:\nhttp://www.telescopes.com
593131
The incident ray is perpendicular to the surface of reflection.\nThen one has the least distance case.
932508
Microwave antenna's with ice shields.
85883
Fiber Optic and Satellite
655068
Actually most of todays satellites use dual polarization. Its not unlike vertical and horizontal polarization of basic radio antennae down here. Some of the earlier sat tv systems had a parobolic dish that would mechanically change polarization to get the other 12 of 24 channels on the satellite system. Multiplexing is another technique that provides more channels.