Uncalibrated S21 behaviour of HP8510B ?
时间：04-08
整理：3721RD
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Hi,
I bought an used HP8510B with HP8341b sweeper and HP8514b S-Parameter test set.
I do not have a proper calibration set yet.
When I do a uncalibrated S21 measurement from 45 mc to 20 gc the transmission trace starts at about -26 dB at 45 mc and then rises to about -2 dB at 1.5 gc. Then
the trace behaves according to the cable loss us to 20 gc. I am a little concerned
about the high attenuation at lower frequencies up to about 1.5 gc.
Is this a "normal" behaviour for the 8510 ?
When I calibrate thru for S21, it works fine. I have a straight line close to 0 dB. When I put attenuators in line, I can measure the correct their values over the whole frequency range.
Thanks!
I bought an used HP8510B with HP8341b sweeper and HP8514b S-Parameter test set.
I do not have a proper calibration set yet.
When I do a uncalibrated S21 measurement from 45 mc to 20 gc the transmission trace starts at about -26 dB at 45 mc and then rises to about -2 dB at 1.5 gc. Then
the trace behaves according to the cable loss us to 20 gc. I am a little concerned
about the high attenuation at lower frequencies up to about 1.5 gc.
Is this a "normal" behaviour for the 8510 ?
When I calibrate thru for S21, it works fine. I have a straight line close to 0 dB. When I put attenuators in line, I can measure the correct their values over the whole frequency range.
Thanks!
Yes, this behaviour is caused by the roll off of the directional couplers at low frequencies. I found this on page 441 of the manual (trace bounce)....