C-Band LNB Teardown

One thought on “C-Band LNB Teardown

  1. C-Band is FAR from dead! In most of the world, especially where it rains a lot, C-band is coveted because the downlink rain fade is roughly 10dB less than at Ku-band (uplink fade is even worse by a couple-few dB). Here in S.E. Asia, we’re suffering from a lack of good, affordable C-band transponder space. There are a lot of VSAT data and voice networks that use C-band.

    Where it rains a lot, for satellite TV you will see L-band downlinks instead of Ku-band. This is again because of the effect of rainfall attenuation on the link budget. These C-band up / L-band down direct broadcast satellites are not your usual “standard” C-band/L-band satellite designs (or “Buses”). The L-band antenna on the satellite is comparatively huge.

    The best PLL LNB’s do not use an internal TCXO reference. Instead they take a 10MHz reference (at around 0dBm) which is multiplexed on the IF coax from the (typically) indoor mounted receiver or modem box.

    I would take that 15K noise figure specification on the DRO LNB with a large does of salt!

    Those “hairpin” filters as you term them are sometimes referred to as a type of “inter-digital” filter. Not that they have anything to do with digital electronics, it’s because the shape of the filter looks like interleaved fingers – fingers are also known as “digits” because you can use them to count.

    Thanks for the tear-down. I enjoyed it very much.

    Regards, David

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