LNB Output Impedances

femi Here are some output impedance plots from a few LNBs. Their DC feed was via the analyser bias port. The analyser is 50 Ohm.

The reference plane was the N type connector. In the case of the SMW QPLL, a cheap Chinese N to F adapter was used which will have introduced some unknowns.

Makers 1 & 2 were set to nominal band edges and others were set to interesting(?) points.

Most of these will cause a few dB of ripple across at least parts of the band on both 50 and 75 Ohm system. However, if you see ripple, it might be from the mismatch on its input as well. Maybe I'll look at receivers another day.

Norsat 9000HX-03b-BN Ka band A

'N' Type Connector

Return loss >11dB from 950-2150MHz

Impedance closer to 50 Ohms than 75

NJRC, NJSS8476EN, C Band, 5150MHz LO

'N' Type Connector

Impedance closer to 50 Ohms than 75

SMW Q-PLL Type C (9750/10600MHz LO) 13V

'F' Type connector

Impedance centred on 50 Ohms in the middle of the band but goes quite capacitive at the high end

SMW Q-PLL Type C (9750/10600MHz LO) 18V

'F' Type connector

Similar to 13V

SMW WDL PLL Type E High band 10600MHz LO

This uses the high band port to feed DC and 10MHz.

2 x N type connectors

Well matched to 50R across the whole band.

SMW WDL PLL Type E Low band 9750MHz LO

This uses the high band port to feed DC and 10MHz.

2 x N type connectors

Reasonable match to 50R across the whole band.

SaTom I found some non-Pro LNBs. They all have F type connectors so I used an SMA to F type adapter which is better than the N type I used previously for F LNBs. THe system was calibrated to the SMA but a reference plane extension was added to take account of the adapter. All are Ku band.

Invacom SNF-031 (New, unused)

This is probably the worst matched of any with real impedances of 25-150 Ohms. This would be mismatched for both 75 & 50 ohms and with a wide spread of inductive and capacitive regions..

MTI AP8-TW (Fron junk heap, may not be fully working)

Looks quite well matched to 75 Ohms.

NJR2184F (An old 10.95-11.7G single band LNB)

Not great but centred on about 80 Ohms from 950-1700MHz

Inverto Black Single (Unused, DRO type)

Around 50 Ohms, from 950-1700, higher & capacitive above that

Sharp BSK2EL200A LNBF

Close to 50 Ohms 1.3-2.3GHz

Sky EL021 (Full band)

Plot does not include the region below 500MHz

Quite good for such a wide band. Centred on about 60 Ohms.