Components of a Dual LNB

LNB stands for low-noise block converter. This is the downlink antenna of a parabolic satellite dish. When two LNBs are in one dish, this becomes a dual band LNB. The LNB may be designed as a feedhorn, that is, an open-ended waveguide constructed with an increasing cross-sectional area. The waveguide is a structure intended to guide electromagnetic and sound waves towards a desired direction.

A dual band LNB with an integrated feedhorn has a pair of low noise blocks attached to the waveguide output probes that are used to down-convert the arriving moderated carrier Ku and C band signal to moderated intermediate frequency signals. In addition, a dual band LNB also has a Ku band waveguide set up on the clamp for changing of focus, a clamp for a Ku band waveguide, and a housing that rotates for a C band coaxial waveguide.

A servomechanism, a device set into motion by another mechanism but which assists that other mechanism’s operation, thrusts the support member to place the energy output coupling probes of the waveguides. This is to suit the polarization of the inward RF energy. This significantly reduces insertion loss and eliminates the need for polarizers. The minimized insertion loss allows defocusing of the Ku band waveguide to broaden the beam width to perk up accuracy without reducing the expansion and degrading performance.

Attached to the outer surface of the housing is a pair of power modules and a position adjustable scalar. The power modules have voltage regulators and transient suppressors attached to the pair of LNB. These block out incoming transients and modify the incoming dc voltage while producing the moderated intermediate frequency carrier signals. Hence, the heat produced by the power modules is set away from the low noise blocks, ensuring an increased life and a better operating performance.

Specific Features

The features specifications of a dual LNB are as follows:

  1. Conversion gain: 58dB (min.)
  2. DC current consumption: 90mA (max.)
  3. Input frequency range:
    • Low band: 10.7~11.7GHz
    • High band: 11.7~12.75GHz

  4. Output frequency range:
    • Low band: 950~1,950GHz
    • High band: 1,100~2,150GHz

  5. L.O. frequency: 9.75/10.6gHz±1MHz (max.) 25°C
  6. L.O. frequency stability: 9.75/10.6GHz ± 2MHz (max.) at -40~+60°C
  7. Output connector type: 75Ω female connector
  8. Output VSWR: 2.0:1 (typical)

Dual LNB with multi-switch for terrestrial television

One dual LNB comes with a multi-switch, enabling dc voltage from the satellite receiver to pass through the terrestrial antenna input without resulting to an alteration or interference of the signal strength of the satellite and the outdoor antenna pictures. By incorporating an external dc block adapter with the LNB, the multi-switch can be used with improved and unimproved antennas without requiring external power injector.