Hi Guys,
I have a few questions regarding vector network analyzers for my further understanding. I am using the Hp 4693B VNA. I wish to compute the input impedance of my device under test. I usually work with the S11 parameters and tailor my device by observing the return loss for my specified bandwidth.
Ok so here's the deal:
I have already simulated my device on an em simulator. It reports an input impedance of X00 ohms. Its not a Tx line! I have connected the dut and measured its S11 parameters(its a one port device, so other scattering parameters are not valid). It reports that the S11(dB) is -XXdB at XXX Mhz.
I can work backwards and extract the input impedance, seen looking from the connector cable's pov. It is complex, therefore, the ref coeff is complex.
gamma= (Zl-Zo)/(Zl+Zo)
Now I can get the plot of the S11 magnitude vs freq. I can also get a smith chart lot of the S11 magnitude and phase. there is also a mode that measures the device imedance.
I guess my question is, is it better to work backwards?
or
If I measure the device impedance, is this the input imedance of the device, seen looking from the cable/network analyzer end? So supose I connect some antenna, I want to measure its input impedance for matching purposes, can I do this on the VNa as I described. I already asked my co-workers and I ot a response.
Its not very clear though. Im thinking that the dut is the load impedance of the vna and cable connector. So this is the imedance seen looking into the cable, the input impedance? The nomenclature is getting me mixed up.
If so, then wouldn't I also have to account for the normalized input impedance? X 50 or whatever cable I use.
Any help will be appreciated.
I have a few questions regarding vector network analyzers for my further understanding. I am using the Hp 4693B VNA. I wish to compute the input impedance of my device under test. I usually work with the S11 parameters and tailor my device by observing the return loss for my specified bandwidth.
Ok so here's the deal:
I have already simulated my device on an em simulator. It reports an input impedance of X00 ohms. Its not a Tx line! I have connected the dut and measured its S11 parameters(its a one port device, so other scattering parameters are not valid). It reports that the S11(dB) is -XXdB at XXX Mhz.
I can work backwards and extract the input impedance, seen looking from the connector cable's pov. It is complex, therefore, the ref coeff is complex.
gamma= (Zl-Zo)/(Zl+Zo)
Now I can get the plot of the S11 magnitude vs freq. I can also get a smith chart lot of the S11 magnitude and phase. there is also a mode that measures the device imedance.
I guess my question is, is it better to work backwards?
or
If I measure the device impedance, is this the input imedance of the device, seen looking from the cable/network analyzer end? So supose I connect some antenna, I want to measure its input impedance for matching purposes, can I do this on the VNa as I described. I already asked my co-workers and I ot a response.
Its not very clear though. Im thinking that the dut is the load impedance of the vna and cable connector. So this is the imedance seen looking into the cable, the input impedance? The nomenclature is getting me mixed up.
If so, then wouldn't I also have to account for the normalized input impedance? X 50 or whatever cable I use.
Any help will be appreciated.