A type of parabolic antenna that is dish-shaped and designed to receive signals (usually in the microwave spectrum of 300 MHz to 300 GHz) from communication satellites is commonly called a satellite dish. For consumers, satellite television is a good example of the use of satellite signals delivered by communication satellites. These signals and transmissions are received by a satellite dish. In North America, television receive-only (TVRO) dishes were originally used for the reception of satellite television from fixed service satellites (FSS). With the advancement of technology, subscription-based DBS services and pay television have become more common, and TVRO is rarely used now.
Having knowledge of the various types of satellite dishes and the basic principles of operation, along with knowledge of parts, accessories, and installation techniques is imperative in order to make a wise satellite purchase. Buyers can find a satellite dish to their liking on eBay, which typically features a huge variety of satellite dishes to serve a diverse clientele.
Principles of Operation
A satellite dish converges the received signals at or near a focal point. The feedhorn is a device mounted on the brackets of the dish that essentially conveys the radio waves between the reflector and the receiver. In the case of a satellite dish, the dish-like portion acts as a reflector, and the feedhorn converts the gathered, reflected, and focused signals into a tiny radio frequency voltage and amplifies it.
Feedhorns are operated at microwave (SHF) and higher frequencies. The feedhorn conducts the signals to low-noise block downconverter (LNB), which converts them from radio waves to electrical signals and changes the band range from the downlinked C-band (or Ku-band) to L-band range.
Types of Satellite Dishes
There are many different types of satellite dishes. The most common types include motorised dishes, VSAT dishes, multi-satellite dishes, automatic tracking dishes, big ugly dishes, and homemade dishes.
Motor-Driven or Motorised Dishes
As the name suggests, these satellite dishes are driven by a motor (servo or stepper). They are usually mounted on a pole and can be rotated and controlled to face any particular satellite location in the sky. DiSEqC, 36v positioners, and USALS are the three popular competing standards, and all are mostly supported by a typical receiver. Enthusiastic buyers mostly opt for motor-driven dishes.
Very small aperture terminal (VSAT) dishes are commonly used for narrowband and broadband data transmission. Point of sale transactions or SCADA are good examples of narrowband transmissions, while VoIP, video, and satellite Internet access services are good examples of broadband transmissions. Another common use of VSAT satellites is for mobile maritime communications.
The diameter of C-band VSATs can be as large as four metres, although more recent VSATs that operate in the Ka band at comparatively higher frequencies are typically 74 to 120 cm in size and offer better performance at a reduced cost.
For some satellite dishes, simultaneous reception from different satellites is possible without the need to re-orient the dish. Multi-satellite dishes are large in size because of double spill over.
Automatic Tracking Satellite Dishes
As the name suggests, these dishes are designed to automatically adjust to track a satellite signal. The main purpose for this type of dish is to be used on moving vehicles, such as news vans and ships, where the dish is not always stationary. A GPS position sensor, gyroscope, unique satellite identification data, and integrated digital video broadcasting (DVB) decoder to aid in the identification of the satellite are all typically utilised by an automatic tracking satellite dish.
Stepper motors are normally used to drive and position these dishes, while gyroscopes determine the changes in position of the vehicle. Other typical parts of an automatic tracking satellite dish include low-noise block converter (LNB), a control unit, and a parabolic reflector. These dishes are mostly used for commercial purposes and are less common for personal use.
Big Ugly Dish (BUD)
Big ugly dish is a colloquial name for television receive-only (TVRO) satellite dishes. Fixed-service satellites transmit satellite television signals that are received by this dish. These C-band dishes rely on unencrypted signals and are usually 2 to 3.5 metres in diameter. Pay television and subscription-based DBS services have become more popular over time, and BUDs are used much less often now.
Ad Hoc / Homemade Dishes
Almost any material that has the ability to reflect radio frequencies can theoretically be used as a reflector antenna. This idea has been practically implemented by technology savvy users who have even used things like dustbin lids and woks to make satellite dishes. By simply utilising LNBs and high transmission signals of DTH satellites, some homemade dishes can receive usable signals.
Typical Satellite Sizes
The different types of satellite dishes have different average diameters. The range of diameters for each of the above mentioned types of satellite dishes is as follows:
Automatic Satellite Dishes
0.74 - 1.2 m
1.77 m (for RV)
2 - 3.5 m
Buyers should keep in mind that different countries have different laws and limitations when it comes to dish sizes. These figures are based on general standards and are subject to change and variation.
Parts of a Satellite Dish
A satellite dish of any type consists of several parts. Some parts are essential requirements for the use of the dish, while others can be categorised as accessories or add-ons.
Usually mounted on the brackets of a parabolic satellite dish, a small antenna that conveys the radio waves between the reflector and the receiver is called a feedhorn (also written as feed horn). A feedhorn is used to convert the radio waves into a tiny radio frequency voltage that is later amplified by the receiver. In satellite dishes, feedhorns are mostly used at microwave and higher frequencies.
Low-noise block downconverters (LNB), low-noise converters (LNC), or low-noise downconverters (LND) are the receiving devices on satellite dishes. A frequency mixer, IF amplifier, local oscillator, and a low-noise amplifier (LNA) combine to form an LNB, which is the most common standard, and the feedhorn conducts the microwave signals and converts them to electrical signals.
A satellite finder (or sat finder) is a device that is used to accurately determine the direction of a geostationary satellite and point the dish in that direction. A wide range of budget and professional satellite finders are available on eBay.
Stepper and Servo Motors
A motor-driven dish uses servo or stepper motors for correct orientation. Most of the time, this type of dish is mounted on a pole. Using the motor, the dish can easily be rotated in any desired direction to fix on a particular geostationary satellite position in the sky. eBay features different varieties of servo and stepper motors that can be used on satellite dishes.
Wall and Ground Mounts
Mounts may be categorised as an accessory by some people, but most buyers prefer wall or ground mounts for their satellite dishes. Both budget and heavy duty mounts for the wall and ground can be found on eBay.
Buying a Satellite Dish on eBay
Different types of satellite dishes, along with numerous parts and accessories, are readily available on eBay. One easy way to find a satellite dish is to enter the name of the desired type of satellite dish in the search bar on the eBay homepage. For example, you might enter motorised satellite dish, VSAT dish, multi-satellite dish, automatic satellite dish, BUD satellite dish, et cetera. For some queries, the results page suggests related searches that are also helpful in finding a particular satellite dish.
Searches for parts for a satellite dish can also be conducted in the same way. Just enter your keywords in the search bar, and the results page gives you a variety of options. Possibilities include feedhorns, LNBs, sat finders, satellite dish motors, wall mount satellite dishes, et cetera.
A good way to save on postage is to enter your postal code under the Distance folder. The results are then narrowed to only include local listings for a particular product. If both parties agree, you can pick up the satellite dish at the close of the auction, rather than have it shipped.
A dish-shaped, parabolic antenna that is designed to receive signals from communication satellites is called a satellite dish. A buyer should have basic knowledge about the various types of satellite dishes, how they function, and the different parts and their respective functions in order to make an informed decision before buying.
The concept of a satellite dish is pretty simple. Radio waves from satellites are received by the dish via the feedhorn, which converts the radio waves into a tiny radio frequency voltage that is conducted to the LNB. It then converts the waves to electrical signals that are passed inside to televisions.
Motorised, VSAT, multi-satellite, automatic, and BUDs are some of the most common types of satellite dishes. The most important parts of these dishes are the feedhorns, LNBs, sat finders, motors and mounts. eBay offers a wide variety of new and used satellite dishes and components in different brands, styles, and price ranges to serve a diverse clientele.