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HF attenuation

Working Group 2.22


The working group operates high precision setups for HF attenuation measurement, both in coaxial line and waveguide for frequencies of up to 50 GHz. Up to attenuation level of 30 dB, the power ratio method is applied which is based on d.c. power substitution. HF power is measured with and without the attenuator under test using a self-adjusting bolometer bridge.

The attenuation of coaxial attenuators up to 100 dB for frequencies up to 40 GHz (up to 120 dB for frequencies up to 1.2 GHz) and of waveguide attenuators up to 60 dB (for frequencies between 8.2 GHz and 50 GHz) is measured by applying the HF series substitution method by comparison with cascaded calibrated reference attenuators.

Due to the mismatch between signal generator and measuring receiver, an additional uncertainty contribution occurs in all attenuation measurements. Independent of the applied measuring method, for each measuring frequency, the insertion point must be matched to the characteristic line impedance by means of suitable tuners. The tuning is carried out by using a vector network analyzer, thus enabling lowest uncertainties. Attenuation measurements with higher uncertainty can be carried using a network analyzer which is traced to the attenuation measuring setups described above.

High frequencies attenuation measurement setup

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Currently, the attenuation measurement setups are extended up to 110 GHz (both coaxial and waveguide).

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