BUC: Block upconverter, K_u band
Top: Hughes 1W
Bottom: Feed horn with short section of waveguide, Andrew 2W BUC and Swedish microwave LNB

BUC: Block upconverter, K_u band
1.2 Andrew dish assembly

Part of a series on
Antennas
Common types Dipole Fractal Loop Monopole Satellite dish Television Whip
Components Balun Block upconverter Coaxial cable Counterpoise (ground system) Feed Feed line Low-noise block downconverter Passive radiator Receiver Rotator Stub Transmitter Tuner Twin-lead
Systems Antenna farm Amateur radio Cellular network Hotspot Municipal wireless network Radio Radio masts and towers Wi-Fi Wireless
Safety and regulation Wireless device radiation and health Wireless electronic devices and health International Telecommunication Union (Radio Regulations) World Radiocommunication Conference
Radiation sources / regions Boresight Focal cloud Ground plane Main lobe Near and far field Side lobe Vertical plane
Characteristics Array gain Directivity Efficiency Electrical length Equivalent radius Factor Friis transmission equation Gain Height Radiation pattern Radiation resistance Radio propagation Radio spectrum Signal-to-noise ratio Spurious emission
Techniques Beam steering Beam tilt Beamforming Small cell Bell Laboratories Layered Space-Time (BLAST) Massive Multiple-input multiple-output (MIMO) Reconfiguration Spread spectrum Wideband Space Division Multiple Access (WSDMA)

A block upconverter (BUC) is used in the transmission (uplink) of satellite signals. It converts a band of frequencies from a lower frequency to a higher frequency. Modern BUCs convert from the L band to K_u band, C band and K_a band. Older BUCs convert from a 70 MHz intermediate frequency (IF) to K_u band or C band.

Most BUCs use phase-locked loop local oscillators and require an external 10 MHz frequency reference to maintain the correct transmit frequency.

BUCs used in remote locations are often 2 or 4 W in the K_u band and 5 W in the C band. The 10 MHz reference frequency is usually sent on the same feedline as the main carrier. Many smaller BUCs also get their direct current (DC) over the feedline, using an internal DC block.

BUCs are generally used in conjunction with low-noise block converters (LNB). The BUC, being an up-converting device, makes up the "transmit" side of the system, while the LNB is the down-converting device and makes up the "receive" side. An example of a system utilizing both a BUC and an LNB is a VSAT system, used for bidirectional Internet access via satellite.

The block upconverter is a block shaped device assembled with the LNB in association with an OMT, orthogonal mode transducer to the feed-horn that faces the reflector parabolic dish. This is opposed to other types of frequency upconverter which may be rack mounted indoors or not co-located with the dish.