In microwave frequencies, do you use a circulator when you need a (near) perfect diode?
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I am confused with the "diode concept" in microwave frequencies. As far as I could read, I found that even small signal Schottky diodes have a non negligible capacitance, that may perturb the signal from 1GHz and more (well I've seen a few that work up to 20GHz but they require special mounting etc.).
On the other hand, there are circulators with operating frequencies from 1GHz to 40GHz, and I think they can be used as a diode since a signal entering at port 1 output at port 2 but the inverse path is blocked. Hence my question: is it what microwave engineers use?
diodes microwave
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add a comment |
$begingroup$
I am confused with the "diode concept" in microwave frequencies. As far as I could read, I found that even small signal Schottky diodes have a non negligible capacitance, that may perturb the signal from 1GHz and more (well I've seen a few that work up to 20GHz but they require special mounting etc.).
On the other hand, there are circulators with operating frequencies from 1GHz to 40GHz, and I think they can be used as a diode since a signal entering at port 1 output at port 2 but the inverse path is blocked. Hence my question: is it what microwave engineers use?
diodes microwave
$endgroup$
add a comment |
$begingroup$
I am confused with the "diode concept" in microwave frequencies. As far as I could read, I found that even small signal Schottky diodes have a non negligible capacitance, that may perturb the signal from 1GHz and more (well I've seen a few that work up to 20GHz but they require special mounting etc.).
On the other hand, there are circulators with operating frequencies from 1GHz to 40GHz, and I think they can be used as a diode since a signal entering at port 1 output at port 2 but the inverse path is blocked. Hence my question: is it what microwave engineers use?
diodes microwave
$endgroup$
I am confused with the "diode concept" in microwave frequencies. As far as I could read, I found that even small signal Schottky diodes have a non negligible capacitance, that may perturb the signal from 1GHz and more (well I've seen a few that work up to 20GHz but they require special mounting etc.).
On the other hand, there are circulators with operating frequencies from 1GHz to 40GHz, and I think they can be used as a diode since a signal entering at port 1 output at port 2 but the inverse path is blocked. Hence my question: is it what microwave engineers use?
diodes microwave
diodes microwave
asked 2 days ago
MikeTeXMikeTeX
657416
657416
add a comment |
add a comment |
3 Answers
3
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$begingroup$
Diodes and circulators are totally different components.
Microwave engineers use one when they want one, the other when they want the other. They use diodes when they want to rectify signals, and circulators when they want to isolate ports.
$endgroup$
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
1
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
In short, no, one would not use a circulator when one needs a diode.
A circulator can't perform the same functions diodes can. For example, diodes can be used as an RF switch (pass RF when supplied with a DC bias, block RF and leave a high-impedance output when no bias is applied), which a circulator cannot do.
$endgroup$
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
add a comment |
$begingroup$
At microwave frequencies one might use a biased pin diode in a duplex port to protect (Block) the Rx LNA input while Tx out on the same coax to the antenna.
However, using a Circulator is somewhat like a Directional coupler except it is undirectional ( in only one direction of the circle ) or "non-reciprocal" feeding only to the next port.
They are made in 3 port and 4 port version.
To achieve isolation and amplification one might choose tunnel diodes or Gunn diodes which due to their avalanche effects have a Negative Differential Resistance
- Then the diode can block the Rx during Tx mode and amplify during Rx mode with proper bias on the diode in a circulator. This is a half-duplex Rx/Tx microwave method used for higher bands of microwave.
[Ref]2
Ref
Ref
$endgroup$
1
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
add a comment |
Your Answer
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Diodes and circulators are totally different components.
Microwave engineers use one when they want one, the other when they want the other. They use diodes when they want to rectify signals, and circulators when they want to isolate ports.
$endgroup$
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
1
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
Diodes and circulators are totally different components.
Microwave engineers use one when they want one, the other when they want the other. They use diodes when they want to rectify signals, and circulators when they want to isolate ports.
$endgroup$
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
1
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
Diodes and circulators are totally different components.
Microwave engineers use one when they want one, the other when they want the other. They use diodes when they want to rectify signals, and circulators when they want to isolate ports.
$endgroup$
Diodes and circulators are totally different components.
Microwave engineers use one when they want one, the other when they want the other. They use diodes when they want to rectify signals, and circulators when they want to isolate ports.
answered 2 days ago
Neil_UKNeil_UK
79k285182
79k285182
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
1
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
1
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
So, what do you do if you need to rectify signals at 40GHz?
$endgroup$
– MikeTeX
2 days ago
1
1
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
@MikeTeX you can use a very tiny diode. It would be more likely called a "power detector" than a "rectifier".
$endgroup$
– The Photon
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
$begingroup$
OK. Just the answer to the question. This helped me to understand what a circulator really is. The other answers give complements though.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
In short, no, one would not use a circulator when one needs a diode.
A circulator can't perform the same functions diodes can. For example, diodes can be used as an RF switch (pass RF when supplied with a DC bias, block RF and leave a high-impedance output when no bias is applied), which a circulator cannot do.
$endgroup$
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
add a comment |
$begingroup$
In short, no, one would not use a circulator when one needs a diode.
A circulator can't perform the same functions diodes can. For example, diodes can be used as an RF switch (pass RF when supplied with a DC bias, block RF and leave a high-impedance output when no bias is applied), which a circulator cannot do.
$endgroup$
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
add a comment |
$begingroup$
In short, no, one would not use a circulator when one needs a diode.
A circulator can't perform the same functions diodes can. For example, diodes can be used as an RF switch (pass RF when supplied with a DC bias, block RF and leave a high-impedance output when no bias is applied), which a circulator cannot do.
$endgroup$
In short, no, one would not use a circulator when one needs a diode.
A circulator can't perform the same functions diodes can. For example, diodes can be used as an RF switch (pass RF when supplied with a DC bias, block RF and leave a high-impedance output when no bias is applied), which a circulator cannot do.
answered 2 days ago
ShamtamShamtam
2,6031023
2,6031023
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
add a comment |
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
This is interesting. I never thought using a diode with a bias tee as a switch. But why not use simply a microwave transistor for this task?
$endgroup$
– MikeTeX
2 days ago
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
$begingroup$
@MikeTeX Cost, control circuitry (two terminal device instead of 3-terminal), switch performance, power handling, etc.
$endgroup$
– Shamtam
yesterday
add a comment |
$begingroup$
At microwave frequencies one might use a biased pin diode in a duplex port to protect (Block) the Rx LNA input while Tx out on the same coax to the antenna.
However, using a Circulator is somewhat like a Directional coupler except it is undirectional ( in only one direction of the circle ) or "non-reciprocal" feeding only to the next port.
They are made in 3 port and 4 port version.
To achieve isolation and amplification one might choose tunnel diodes or Gunn diodes which due to their avalanche effects have a Negative Differential Resistance
- Then the diode can block the Rx during Tx mode and amplify during Rx mode with proper bias on the diode in a circulator. This is a half-duplex Rx/Tx microwave method used for higher bands of microwave.
[Ref]2
Ref
Ref
$endgroup$
1
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
At microwave frequencies one might use a biased pin diode in a duplex port to protect (Block) the Rx LNA input while Tx out on the same coax to the antenna.
However, using a Circulator is somewhat like a Directional coupler except it is undirectional ( in only one direction of the circle ) or "non-reciprocal" feeding only to the next port.
They are made in 3 port and 4 port version.
To achieve isolation and amplification one might choose tunnel diodes or Gunn diodes which due to their avalanche effects have a Negative Differential Resistance
- Then the diode can block the Rx during Tx mode and amplify during Rx mode with proper bias on the diode in a circulator. This is a half-duplex Rx/Tx microwave method used for higher bands of microwave.
[Ref]2
Ref
Ref
$endgroup$
1
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
add a comment |
$begingroup$
At microwave frequencies one might use a biased pin diode in a duplex port to protect (Block) the Rx LNA input while Tx out on the same coax to the antenna.
However, using a Circulator is somewhat like a Directional coupler except it is undirectional ( in only one direction of the circle ) or "non-reciprocal" feeding only to the next port.
They are made in 3 port and 4 port version.
To achieve isolation and amplification one might choose tunnel diodes or Gunn diodes which due to their avalanche effects have a Negative Differential Resistance
- Then the diode can block the Rx during Tx mode and amplify during Rx mode with proper bias on the diode in a circulator. This is a half-duplex Rx/Tx microwave method used for higher bands of microwave.
[Ref]2
Ref
Ref
$endgroup$
At microwave frequencies one might use a biased pin diode in a duplex port to protect (Block) the Rx LNA input while Tx out on the same coax to the antenna.
However, using a Circulator is somewhat like a Directional coupler except it is undirectional ( in only one direction of the circle ) or "non-reciprocal" feeding only to the next port.
They are made in 3 port and 4 port version.
To achieve isolation and amplification one might choose tunnel diodes or Gunn diodes which due to their avalanche effects have a Negative Differential Resistance
- Then the diode can block the Rx during Tx mode and amplify during Rx mode with proper bias on the diode in a circulator. This is a half-duplex Rx/Tx microwave method used for higher bands of microwave.
[Ref]2
Ref
Ref
answered 2 days ago
Sunnyskyguy EE75Sunnyskyguy EE75
71.4k227103
71.4k227103
1
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
add a comment |
1
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
1
1
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
$begingroup$
Thank you for this nice answer, full of side information.
$endgroup$
– MikeTeX
2 days ago
add a comment |
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