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Reistor frequency response

Discussion in 'Electronic Design' started by Reg Edwards, Jul 17, 2005.

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  1. Reg Edwards

    Reg Edwards Guest

    FREQUENCY RESPONSE OF RESISTORS.

    Program METALFLM.exe 41 Kbytes.

    This program models small low-wattage wire-ended resistors including
    spiralled metal-film resistors. The model's equivalent circuit is a
    chain of T and L networks. Values of lumped inductance and stray
    capacitance are estimated by the program from the component's physical
    dimensions.

    The component with it's terminating leads is treated as a lumped L and
    C non-uniform transmission line. The program computes input impedance
    from 10 KHz up to 5 GHz with the other end grounded. Fast and slow
    frequency sweeps are available to observe maxima and minima of Zin.

    Max and min Zin are approximately related to the physical length of
    the component, including connecting leads, but occur at frequencies
    far higher than the usual and useful working frequency range.

    The reflection cefficient and standing-wave-ratio are calculated with
    reference to Zo, Zo being the DC value of the resistor. The usefulness
    of the component as a dummy load or for other purposes at any
    frequency can then be ascertained.

    The effectiveness versus frequency of solid carbon-rod resistors and
    multi-turn UHF chokes, which are of similar wire-end construction, can
    also be determined. Chokes can be wound over the bodies of high-value
    wire-ended resistors, the parallel resistance value perhaps having
    some desirable effect on the ultimate response.

    Another use for resistors having a good high frequency response, or at
    least a known frequency response, is for ratio arms and switched
    resistors in impedance bridges and other measuring instruments.

    Download METALFLM in a few seconds and run immediately.
    ----
    ............................................................
    Regards from Reg, G4FGQ
    For Free Radio Design Software go to
    http://www.btinternet.com/~g4fgq.regp
    ............................................................
     
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