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The S parameters of an attenuator--but what is actually wrong with it?
Clash Royale CLAN TAG#URR8PPP
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I have measured S parameters of an 10 dB attenuator on hand--please see the attachment.
In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation but rather it is giving ~20 dB attenuation (but varying over frequency).
the reflections, |S11|, are just too high. Also |S22| are just too high in low frequency, but high frequencies it is low.
But my question is, if you are asked to describe the characteristics of such an attenuator, then what else would you say?
Thank you
rf
asked 2 hours ago
learning
455
add a comment |Â
up vote
2
down vote
favorite
I have measured S parameters of an 10 dB attenuator on hand--please see the attachment.
In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation but rather it is giving ~20 dB attenuation (but varying over frequency).
the reflections, |S11|, are just too high. Also |S22| are just too high in low frequency, but high frequencies it is low.
But my question is, if you are asked to describe the characteristics of such an attenuator, then what else would you say?
Thank you
rf
asked 2 hours ago
learning
455
Are you comparing dB amplitude with dB power? In which case you will be a factor of two off.
– Jack B
2 hours ago
I have the measurement results of a "good" 10 dB attenuator, which shows the flat -10 dB attenuation level of |S21| / |S12|. So, I "think" the VNA converts in proper dB sense as 20*log10(abs(Sxx)), where abs(Sxx) is in amplitude sense.
– learning
2 hours ago
Is this a coaxial attenuator, did you use the correct torque wrench to make all connections (cable to VNA, VNA to DUT, VNA to standards during calibration)? If this is an on-chip attenuator or you're using microprobes to connect to it, are you sure you landed the probes correctly?
– The Photon
29 mins ago
It's a coaxial attenuator. Yes, I made sure all the connections are good.
– learning
16 mins ago
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
I have measured S parameters of an 10 dB attenuator on hand--please see the attachment.
In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation but rather it is giving ~20 dB attenuation (but varying over frequency).
the reflections, |S11|, are just too high. Also |S22| are just too high in low frequency, but high frequencies it is low.
But my question is, if you are asked to describe the characteristics of such an attenuator, then what else would you say?
Thank you
rf
asked 2 hours ago
learning
455
I have measured S parameters of an 10 dB attenuator on hand--please see the attachment.
In my view, this attenuator is not performing as expected, e.g., |S12| / |S21| is not giving 10dB attenuation but rather it is giving ~20 dB attenuation (but varying over frequency).
the reflections, |S11|, are just too high. Also |S22| are just too high in low frequency, but high frequencies it is low.
But my question is, if you are asked to describe the characteristics of such an attenuator, then what else would you say?
Thank you
rf
rf
asked 2 hours ago
learning
455
asked 2 hours ago
learning
455
asked 2 hours ago
learning
455
asked 2 hours ago
learning
455
asked 2 hours ago
learning
455
455
Are you comparing dB amplitude with dB power? In which case you will be a factor of two off.
– Jack B
2 hours ago
I have the measurement results of a "good" 10 dB attenuator, which shows the flat -10 dB attenuation level of |S21| / |S12|. So, I "think" the VNA converts in proper dB sense as 20*log10(abs(Sxx)), where abs(Sxx) is in amplitude sense.
– learning
2 hours ago
Is this a coaxial attenuator, did you use the correct torque wrench to make all connections (cable to VNA, VNA to DUT, VNA to standards during calibration)? If this is an on-chip attenuator or you're using microprobes to connect to it, are you sure you landed the probes correctly?
– The Photon
29 mins ago
It's a coaxial attenuator. Yes, I made sure all the connections are good.
– learning
16 mins ago
add a comment |Â
Are you comparing dB amplitude with dB power? In which case you will be a factor of two off.
– Jack B
2 hours ago
I have the measurement results of a "good" 10 dB attenuator, which shows the flat -10 dB attenuation level of |S21| / |S12|. So, I "think" the VNA converts in proper dB sense as 20*log10(abs(Sxx)), where abs(Sxx) is in amplitude sense.
– learning
2 hours ago
Is this a coaxial attenuator, did you use the correct torque wrench to make all connections (cable to VNA, VNA to DUT, VNA to standards during calibration)? If this is an on-chip attenuator or you're using microprobes to connect to it, are you sure you landed the probes correctly?
– The Photon
29 mins ago
It's a coaxial attenuator. Yes, I made sure all the connections are good.
– learning
16 mins ago
Are you comparing dB amplitude with dB power? In which case you will be a factor of two off.
– Jack B
2 hours ago
Are you comparing dB amplitude with dB power? In which case you will be a factor of two off.
– Jack B
2 hours ago
I have the measurement results of a "good" 10 dB attenuator, which shows the flat -10 dB attenuation level of |S21| / |S12|. So, I "think" the VNA converts in proper dB sense as 20*log10(abs(Sxx)), where abs(Sxx) is in amplitude sense.
– learning
2 hours ago
I have the measurement results of a "good" 10 dB attenuator, which shows the flat -10 dB attenuation level of |S21| / |S12|. So, I "think" the VNA converts in proper dB sense as 20*log10(abs(Sxx)), where abs(Sxx) is in amplitude sense.
– learning
2 hours ago
Is this a coaxial attenuator, did you use the correct torque wrench to make all connections (cable to VNA, VNA to DUT, VNA to standards during calibration)? If this is an on-chip attenuator or you're using microprobes to connect to it, are you sure you landed the probes correctly?
– The Photon
29 mins ago
Is this a coaxial attenuator, did you use the correct torque wrench to make all connections (cable to VNA, VNA to DUT, VNA to standards during calibration)? If this is an on-chip attenuator or you're using microprobes to connect to it, are you sure you landed the probes correctly?
– The Photon
29 mins ago
It's a coaxial attenuator. Yes, I made sure all the connections are good.
– learning
16 mins ago
It's a coaxial attenuator. Yes, I made sure all the connections are good.
– learning
16 mins ago
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
6
down vote
accepted
It is very likely that port 1 of the attenuator has a bad connection, possibly due to a broken connector. Somewhere, the RF is passing through a capacitive coupling instead of a direct connection.
Evidence:
1) Attenuation is higher than expected - 20dB instead of 10dB
2) The match is asymmetric - port 2 is well matched, port 1 is basically reading an open circuit.
You can verify this with a multimeter. A healthy attenuator will read some resistance (say, <100 ohm) between the input and output, and similar between each input and ground. Your attenuator, I believe, will read an open circuit between input and output.
answered 1 hour ago
Selvek
1,759111
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
6
down vote
accepted
It is very likely that port 1 of the attenuator has a bad connection, possibly due to a broken connector. Somewhere, the RF is passing through a capacitive coupling instead of a direct connection.
Evidence:
1) Attenuation is higher than expected - 20dB instead of 10dB
2) The match is asymmetric - port 2 is well matched, port 1 is basically reading an open circuit.
You can verify this with a multimeter. A healthy attenuator will read some resistance (say, <100 ohm) between the input and output, and similar between each input and ground. Your attenuator, I believe, will read an open circuit between input and output.
answered 1 hour ago
Selvek
1,759111
add a comment |Â
up vote
6
down vote
accepted
It is very likely that port 1 of the attenuator has a bad connection, possibly due to a broken connector. Somewhere, the RF is passing through a capacitive coupling instead of a direct connection.
Evidence:
1) Attenuation is higher than expected - 20dB instead of 10dB
2) The match is asymmetric - port 2 is well matched, port 1 is basically reading an open circuit.
You can verify this with a multimeter. A healthy attenuator will read some resistance (say, <100 ohm) between the input and output, and similar between each input and ground. Your attenuator, I believe, will read an open circuit between input and output.
answered 1 hour ago
Selvek
1,759111
add a comment |Â
up vote
6
down vote
accepted
up vote
6
down vote
accepted
It is very likely that port 1 of the attenuator has a bad connection, possibly due to a broken connector. Somewhere, the RF is passing through a capacitive coupling instead of a direct connection.
Evidence:
1) Attenuation is higher than expected - 20dB instead of 10dB
2) The match is asymmetric - port 2 is well matched, port 1 is basically reading an open circuit.
You can verify this with a multimeter. A healthy attenuator will read some resistance (say, <100 ohm) between the input and output, and similar between each input and ground. Your attenuator, I believe, will read an open circuit between input and output.
answered 1 hour ago
Selvek
1,759111
It is very likely that port 1 of the attenuator has a bad connection, possibly due to a broken connector. Somewhere, the RF is passing through a capacitive coupling instead of a direct connection.
Evidence:
1) Attenuation is higher than expected - 20dB instead of 10dB
2) The match is asymmetric - port 2 is well matched, port 1 is basically reading an open circuit.
You can verify this with a multimeter. A healthy attenuator will read some resistance (say, <100 ohm) between the input and output, and similar between each input and ground. Your attenuator, I believe, will read an open circuit between input and output.
answered 1 hour ago
Selvek
1,759111
answered 1 hour ago
Selvek
1,759111
answered 1 hour ago
Selvek
1,759111
answered 1 hour ago
Selvek
1,759111
1,759111
add a comment |Â
add a comment |Â
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Are you comparing dB amplitude with dB power? In which case you will be a factor of two off.
– Jack B
2 hours ago
I have the measurement results of a "good" 10 dB attenuator, which shows the flat -10 dB attenuation level of |S21| / |S12|. So, I "think" the VNA converts in proper dB sense as 20*log10(abs(Sxx)), where abs(Sxx) is in amplitude sense.
– learning
2 hours ago
Is this a coaxial attenuator, did you use the correct torque wrench to make all connections (cable to VNA, VNA to DUT, VNA to standards during calibration)? If this is an on-chip attenuator or you're using microprobes to connect to it, are you sure you landed the probes correctly?
– The Photon
29 mins ago
It's a coaxial attenuator. Yes, I made sure all the connections are good.
– learning
16 mins ago