Here is a brief description of LNBFs for FTA reception.
A LNBF is a LNB with an attached feedhorn. LNBF polarity is usually controlled by voltage selection by the receiver and powered through the coax cable. LNBFs can be configured as a single feedhorn with reception of one satellite or two, three and recently four feedhorns for reception of multiple satellite from one fixed position dish. The LNBFs can be configured with many different outputs, supporting single tuner receivers or multiple tuners, with band-stacked frequencies or various switching methods allowing multiple receivers to receive programming from multiple satellites simultaneously.
There are 3 basic frequency ranges for consumer equipment in North America.
C-Band 3 - 4 GHz / 8 - 10 foot usual dish size
KU-Band 10 - 12 GHz / 30" - 4' usual dish size
KA-Band 18 - 20 GHz / 2' - 5' usual dish size
C-Band signals are transmitted in linear and circular polarizations. Most North American satellites transmit a linear polarization, but most of North America is covered by satellite footprints with circular polarization as well. Reception of circular polarized signals with a linear LNB is possible, but the signal will be attenuated by approximately 3dB (each 3 dB indicates a doubling of signal strength). Reception of some signals require the use of an extended frequency range LNB, though this is not common usage.
KU-Band Signals are transmitted in both Linear and circular polarizations. Most transmissions by Dish Network, Bell ExpressView and DirecTV currently are circular polarization and use the upper portion of the KU-Band from 12.2 - 12.75 GHz. (Note: recently the FCC allowed Dish Network to transmit 11.7 - 12.2 GHz, circular polarization in one orbital slot.) Most FTA transmissions in North America are linear polarity and use the middle of the KU-Band from 11.7 - 12.2 GHz and can be received using a linear standard LNB. There are additional KU frequencies that use the lower KU frequencies from 10.7 to 11.7 GHz. These lower frequency signals are received with an Universal LNBF, which can also receive the 11.7 to 12.2 frequencies. These signals can often be received in the US, but usually they are stations that are originating from satellites not specifically targeting the US Direct to Home market or are from international satellites. Standard linear LNBFs normally outperform Universal linear type LNBFs. There are several channels that normally can only be received with a Universal linear LNBF, but often, specific receivers allow the scanning of these channels using a standard LNBF as these receivers have the ability to scan frequencies below the standard low IF frequency of the 950MHz cut-off frequency.
KA-Band frequencies are transmitted in both linear and circular polarities and divided into two bands, 18.3 - 18.8 GHz and 19.7 - 20.2 GHz. KA-Band LNBFs are not currently readily available as KU single LNBFs, but are available in monoblock configurations with DirecTV and Dish Network multi-LNBF arrays. Very little programming is currently available for FTA. Expect increased use during the next few years.
What LNBF is best for your KU reception? If you wish to receive programming from more that two satellites, purchase a single LNBF with a motorized system. If you are interested in only 1, 2 or 3 satellites that are located within 10 or 15 degrees, you could use a single non-motorized dish with several LNBFs mounted in adjustable LNBF clamps (Note: satellites also would need to separated by at least 4 or 5 degrees).
EXAMPLE 1 EXAMPLE 2 Purchase a Universal LNBF if you wish to receive programming from international satellites, otherwise a standard LNBF will usually provide better reception of the majority of signals available in the US and Canada.
Though Satellite AV chooses to no longer to distribute Invacom products, I would suggest that the QPH-031 combined Circular and Linear KU standard LNBF is a great LNBF that will receive the majority of FTA signals that the average viewer wishes to receive.
