Impedance of components at high frequencies
HP 4396A 100kHz-1.8GHz analyzer with HP 8504A 300kHz-3GHz s parameter test set

HP 4396A 100kHz-1.8GHz analyzer with HP 8504A 300kHz-3GHz s parameter test set

Some of the tested components: 1nF flim capacitor, 100nF ceramic capacitor, 560Ω resistor, a coil and electrolytic capacitor.

Some of the tested components

So I played around with some tools in Satellite laboratory. This time measured impedances of different electronic components. I used this weird network analyzer to generate signals and measure reflecting patterns. It plotted impedances on frequencies from 300kHz to 1.8GHz on its beautiful CRT display. I made pictures of two displays: Smith chart showing the impedance on different frequencies, and phase angle graph. The display was normalized on 50Ω load.

Smith chart shows the resistance on horizontal scale, and the reactance on vertical one. The line on the display shows impedance on different frequencies. If the line is above the centre line then the load is inductive. If it is below - capacitive. The middle point of the graph is 50Ω. Because ideal resistor is not reactive, it should be a dot on the middle line. Ideal reactive elements should be curves on the other graph (see the pictures).

1nF thick film capacitor, being pretty ideal in 10-20MHz range.

1nF thick film capacitor, being pretty ideal in 10-20MHz range.

1nF thick film capacitor, on higher frequencies - an inductor...

1nF thick film capacitor, on higher frequencies - an inductor...

Phase shift graph of 1nF film capacitor

Phase shift graph of 1nF film capacitor

10nF capacitor, looking like an induktor

10nF capacitor, looking like an induktor

Phase shift graph of 10nF ceramic capacitor

Phase shift graph of 10nF ceramic capacitor

680Ω carbon resistor doing tricks

680Ω carbon resistor doing tricks

Self made coil, being what it should be - ugly

Self made coil, being what it should be - ugly

Phase shift diagram of the same coil

Phase shift diagram of the same coil

10uF aluminium electrolytic capacitor being a perfect inductor

10uF aluminium electrolytic capacitor being a perfect inductor

Testing ferrite bead, the cheapest 0603 one from the farnell

Testing ferrite bead, the cheapest 0603 one from the farnell

Response from ferrite bead, i have no idea what it means

Response from ferrite bead, i have no idea what it means

Coilcraft high frequency inductor - finally some near-perfect response

Coilcraft high frequency inductor - finally some near-perfect response

Tested component - Coilcraft 0906-2 RF inductor

Tested component - Coilcraft 0906-2 RF inductor

2 thoughts on “Impedance of components at high frequencies

  1. Hi Guy, very nice images of capacitance and inductance response. However it should be nice if you could demonstrate how to analyse it using an ordinary frequency generator and oscilloscope. Using an expansive network/frequency analyzer is out of the question for a hobbyist. Thank you!

  2. Normally you use components for RF that are meant for RF. But I will be writing more posts about low cost RF measurements and testing in the future.

    There are several ways how to use frequency generator and oscilloscope to analyse filters, but they are all for quite low frequencies (<100MHz).

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