Parabolic Satellite Dish Antenna
Without getting into all the gory math and physics, a parabolic dish antenna is what allows satellite TV transmission. Its unique dish-shape reflector focuses the beam of data transmitted both to and from the parabolic antenna, thus allowing precise data transmission while using reasonably small antennas. The satellite TV revolution was made possible by this late 19th century invention. And now, the details:
What is a parabolic dish antenna?
All satellite TV antennas are parabolic antennas. A parabolic dish antenna is a High-Gain Antenna (HGA) reflector, which is one where the width of the radio wave, beaming to and from it, is narrowly focused. If you were to see one, you would know it as a satellite dish antenna, though they are also used for the transmission and reception of data, radar, radio and cellular phone companies use these types of antennas as well.
The parabolic dish antenna is sometimes also called a parabolic satellite dish – though satellite dish antennas can be oval in shape. The parabolic dish antenna is made with a parabolic reflector that is circle shaped. A circular reflector, ideally, produces a pencil-like beam, while the beam of an oval one is rather more like a fan beam. What makes the parabolic satellite dish a high-gain antenna is the fact that it increases its power in a reciprocal way. When it transmits, it focuses its power as it sends. When it receives, it focuses the same, equal amount of increased power to capturing the signal. Signal strength is very important for satellite TV antennas.
The first of this type of antenna to hit the world scene was made in 1888 by a physicist named Heinrich R. Hertz, of German descent. He fashioned two antennas. One sent and the other received. His work is considered to have been the beginnings of radio, radar and more than 120 years after his first antennas, the present wireless world. Today, one can hardly navigate through this country’s cities and suburbs or stretches of open land without seeing a TV antenna dish. And my guess is that very soon, a whole generation will never have known a day without the pleasures of high definition television brought to them by the HD antenna satellite dish.
How does the parabolic satellite dish work?
Ask anyone what a satellite dish antenna looks like and they’ll say, “It’s a round bowl with a thing sticking out of the middle.” The structure is essentially that simple. A TV antenna satellite dish is made up of:
- A reflector (made of a metallic covered area)
- A feed unit called a horn or antenna protruding from it
If we stick to the topic of satellite TV antennas, the path of the signal is easy enough to follow. First of all, we can’t wave an arm in the air without crossing a satellite beam. Satellite beams, like those from a TV antenna satellite dish or cellular phones, are beaming down, around and about us all the time. The question is, how does a satellite dish antenna catch the one signal meant for you and turn it into the Boxing match or the latest episode of your favorite show?
In the sky, satellite TV providers like DISH Network® and DIRECTV® launch geosynchronous satellites into orbit. These are large satellite dish antennas, which move in sync with the rotation of the Earth. The look like they are fixed in space, but they are moving. If the satellite TV antennas were stationary, then the TV antenna dish on your roof would have to rotate in order to pull in signals. In fact, that wouldn't be enough! Viewers would have to rotate their satellite TV antennas during half of the day, while they wouldn't be able to receive any signal through their satellite dish antennas during the other half.
The parabolic shape of the reflectors in the satellite dish antennas is the key. If you think about the satellite TV antennas like open umbrellas, then the handles are like the feed horns. A signal from the orbiting satellite dish antenna is aimed precisely at the TV antenna satellite dish on your apartment building and it gets caught in the reflector. Because of its shape, the signal gets bounced around inside and is then collected in the feed horn and transferred to the low noise block. Here the high frequencies of the microwave signals are converted to lower frequencies that travel through a cable to the Dish Network receiver in your living room so you can watch your favorite shows.
Does HDTV require a dedicated HD antenna satellite dish?
DIRECTV requires HDTV customers to get its new DIRECTV Slimline dish. It is an oval 22.5 in. x 32.5 in. HD antenna satellite dish that stands out from the other TV antenna dish models they feature. It is a 5 LNB with an easy on the eyes slimmer design for those who don’t want a big ugly satellite dish antenna on the roof of their sleek home.
DISH Network has topped their line with an elliptical reflector TV antenna satellite dish they call the SuperDISH. The 36" x 20" TV antenna dish is an HD antenna satellite dish that captures local, international language, audio channels and more - from 3 different satellites in orbit! The best way to enjoy DISH Network HD channles is with the HD SuperDISH.
While the new TV antenna satellite dish pulls in hundreds of channels Professor Heinrich Hertz may never have imagined, the look of the TV antenna dish is still very close to the one he built out of wood and metals more than a century ago. As we enjoy our television in HD, antenna satellite dish technology carries out his vision, roughly as he designed it.
Disclaimer: Please note that this article was written when the satellite TV provider DISH was branded as DISH Network. As of 2/1/2012 DISH Network has changed their branding name to DISH. Article post date: 12/25/2009.