margek
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Hi everybody! Sorry for very long question. My question is first of all about FEKO 6.3. I hope somebody dealt with this version of this software. I downloaded it from official site (FEKO LITE version). Compared to previous old versions i dealt with, there is possible to choose either "Standard configuration" or "Multiport S-parameter". I made modeling of quadrifilar helix using both. I expected results to coincide. But they doesn't!!!
First pair of opposite volutes is fed using 1 voltage source (with 50 Ohm internal impedance) in the centre of wire. Another pair (perpendicular to first) is fed using another voltage source with the same amplitude and ΔΦ=90 deg phase shift.
I made 2 calculations for each case (configuration):
a) first generator is ON;second is off (i. e. there is only 50 Ohm load instead of generator)
b) Two generators are ON.
I interested in S11 and so called (in HFSS) "ACTIVE S11", i.e.
full reflection coefficient, that accounts coupling S12 between ports and phase difference ΔΦ between them. It is of interest in phased array analysis for instance.
This means that in "Multiport S-parameter" configuration i need to calculate
"a)" S11.
"b)"
| |S11|•ejΦ11 + |S12|•ej(Φ12+ΔΦ) |
in dB,
where ΔΦ - phase difference between 2 sources (as i told earlier).
For "Standard configuration", as far as i understand to calculate "a)" i need to set amplitudes A1=1, A2=0. For "b)" i need to set A1=A2=1 and ΔΦ=90 deg. And in this case "Reflection coefficient" in PostFeko will give me ACTIVE S11 (Am i right?).
But results of this two configurations do not agree. Take a look at picture i added "comparison results.png". Standard configuration is on the left side and Multiport S-parameter is on the right. 1 and 2 not yet coincide. 3 and 4 also not coincide. More over dependence "1" is equal to that in case of shorted second generator. So "2" looks more real than "1" in this case. But what is dependence "3"?
I bit confused about it all. Can anyone explain and clear me this points.
I also attached FEKO projects.
Uffff.... tired to write this post. Thanks in advance....
First pair of opposite volutes is fed using 1 voltage source (with 50 Ohm internal impedance) in the centre of wire. Another pair (perpendicular to first) is fed using another voltage source with the same amplitude and ΔΦ=90 deg phase shift.
I made 2 calculations for each case (configuration):
a) first generator is ON;second is off (i. e. there is only 50 Ohm load instead of generator)
b) Two generators are ON.
I interested in S11 and so called (in HFSS) "ACTIVE S11", i.e.
full reflection coefficient, that accounts coupling S12 between ports and phase difference ΔΦ between them. It is of interest in phased array analysis for instance.
This means that in "Multiport S-parameter" configuration i need to calculate
"a)" S11.
"b)"
| |S11|•ejΦ11 + |S12|•ej(Φ12+ΔΦ) |
in dB,
where ΔΦ - phase difference between 2 sources (as i told earlier).
For "Standard configuration", as far as i understand to calculate "a)" i need to set amplitudes A1=1, A2=0. For "b)" i need to set A1=A2=1 and ΔΦ=90 deg. And in this case "Reflection coefficient" in PostFeko will give me ACTIVE S11 (Am i right?).
But results of this two configurations do not agree. Take a look at picture i added "comparison results.png". Standard configuration is on the left side and Multiport S-parameter is on the right. 1 and 2 not yet coincide. 3 and 4 also not coincide. More over dependence "1" is equal to that in case of shorted second generator. So "2" looks more real than "1" in this case. But what is dependence "3"?
I bit confused about it all. Can anyone explain and clear me this points.
I also attached FEKO projects.
Uffff.... tired to write this post. Thanks in advance....
