Why dish antenna is designed in that shape?

Answer 1

A satellite dish is a type of parabolic antenna designed with the specific purpose of transmitting signals to and/or receiving from satellites. A satellite dish is a particular type of microwave antenna.

The parabolic antenna is a high-gain reflector antenna used for radio, television and data communications, and also for radiolocation (RADAR), on the UHF and SHF parts of the electromagnetic spectrum. The relatively short wavelength of electromagnetic (radio) energy at these frequencies allows reasonably sized reflectors to exhibit the very desirable highly directional response for both receiving and transmitting.


A typical parabolic antenna consists of a parabolic reflector illuminated by a small feed antenna.
The reflector is a metallic surface formed into a paraboloid of revolution and (usually) truncated in a circular rim that forms the diameter of the antenna. This paraboloid possesses a distinct focal point by virtue of having the reflective property of parabolas in that a point light source at this focus produces a parallel light beam aligned with the axis of revolution.
The feed antenna is placed at the reflector focus. This antenna is typically a low-gain type such as a half-wave dipole or a small waveguide horn. In more complex designs, such as the Cassegrain antenna, a sub-reflector is used to direct the energy into the parabolic reflector from a feed antenna located away from the primary focal point. The feed antenna is connected to the associated radio-frequency (RF) transmitting or receiving equipment by means of a coaxial cable transmission line or hollow waveguide.

Answer 2

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.

Answer 3

Ok, answers here one at a time... Effectof of mixing gas with different octanes? If you mix 5 gallons of 91 octane (R+M/2) with 5 gallons of 100 octane (R+M/2), then you'll have 10 gallons of ~96 Octane. Of course, since you're talking about 115 octane, you're also talking about mixing leaded and unleaded (100 octane by R+M/2 is the highest level of unleaded). So, unless this is an older car that was desinged to run leaded fuel, you'll have some other problems. Leaded gas will leave deposits on spark plugs and valves. This was often desirable in older cars designed for leaded fuels since it helped lube the valve seats. But these deposits are not desirable in modern engines. The lead will cause damage to the catalytic converter and the O2 sensor, and cause other ODB2 issues (you will likely need to replace the cat and the O2). Of course, the real question is why would you want to do this? Just for the thrill of spending a much larger amount for a tank of gas? The only performance advantage you'll get will be from the extra lightening of you wallet. Octane measures the ability of gas to resist predetonation. If your car is designed for 87 Octane (again, R+M/2 since there are different methods of rating octane), then the ideal for you to use is 87! Using more gets you exactly nothing - in fact, if you work out the math, you will find you actually lose some efficancy (although when it's all said and done, probably not enough to make any difference). Your Maxima is rated for 91 Octane Premium... this means 91 (or whatever premium is available) is what should be used, simplae as that. This only gets more complicated in two sitations: In many modern cars there are knock sensors that will detect predetonation and detune the engine to protect it... this means you can run 87 octane in a car that "requires" 91, but you will lose power as the spark will normally be retarded under these conditions - so in that instance, using a higher octane will gain you something (or rather, it will no lose you anything; again, the recommended is best). The other situation is a modified car. Just as a knock sensor will retard the spark to protect for lower quality gas, you could advance the spark to account for higher quality (or other mods)... of course that means you will ALWAYS need to run that higher octane. Lastly, IF you do not have a knock sensor and you are in a suitation where you know your car would be under heavy load (uphill towing on a hot day?), then it might be wise to mix in a gallon or two of higher than recommended octane as extra protection (but again, not of leaded fuel).

Answer 4

A convex lens will focus the energy of the sun on a single focal point allowing you to light a fire using sunlight by placing an object to be burned at the focus point.

The convex lens fore microwave radiation is the dish, which focuses the weak signal collected by the dish and transmits it to the receiver located at the focus point.

Answer 5

A parabolic reflector reflects parallel (from a distant source) to a point called the focus.

Answer 6

To amplify or increase gain of the signal