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.


    1.2m Prodelin 3122 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): SMW Q-PLL type C, Prodelin feed. Ku (Extended): 11.3GHz LO SMW & Prodelin Feed Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Dear, S-!


    Great study the LNB impedances, thank you.

    I like the Smith chart presentation, good showing this measuring values, i using this chart to the my waveguide planning works also.

    (Paul Wade presented in 2001 the "Circular Waveguide experiement" studis, this articel my planning basis.)


    I have question:

    Do you make also the "comercial" KU LNB measuring?

    Example, Inverto IDLP S-Flange, Invacom SNF/QTF, MTI AP8, etc.. This is types, working in the 75 impedance, I would like to know,, how working in the realistic system.


    Greating thanks!


    SaTom

    Andrew 370 cm PFA (26E/28.2E UK); 2x180 cm PFA (7E EUB,W; 7W NWA,MENA); Parsat 220 cm PFA; Hirschmann 130 cm (26E); SAB 100 cm (52E E,W); Wavefrontier T90 (5W, 4W, 0.8W, 9E, 13E, 19E, 31,5E) Visiosat 96 Gregorian

    Dr. HD Grand Triple; Illusionsat M3; iBravebox V7; TBS6903; GoldMaster SR-525; Amiko A5 Combo; GTMedia GT Combo

  • 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.


    1.2m Prodelin 3122 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): SMW Q-PLL type C, Prodelin feed. Ku (Extended): 11.3GHz LO SMW & Prodelin Feed Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Dear, S-!


    Thank you this test, and the your work.

    Hmm, suprised me this report.

    Many bad value in the commercial category, not I would have thought that Invacom the worst.

    I think the MTI is rleative good LNB, maybe the best the KU band IF frequency range impedance relations.


    (But, unfortunately the MTI AP8, not the best sensitive LNB for DX.

    I tested the few years ago, the Inverto White Tech IDLP S-Flange more sensitive, I still use it to this day.)


    Best regards,

    SaTom

    Andrew 370 cm PFA (26E/28.2E UK); 2x180 cm PFA (7E EUB,W; 7W NWA,MENA); Parsat 220 cm PFA; Hirschmann 130 cm (26E); SAB 100 cm (52E E,W); Wavefrontier T90 (5W, 4W, 0.8W, 9E, 13E, 19E, 31,5E) Visiosat 96 Gregorian

    Dr. HD Grand Triple; Illusionsat M3; iBravebox V7; TBS6903; GoldMaster SR-525; Amiko A5 Combo; GTMedia GT Combo

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